tools/virtio: add ringtest utilities
This adds micro-benchmarks useful for tuning virtio ring layouts. Three layouts are currently implemented: - virtio 0.9 compatible one - an experimental extension bypassing the ring index, polling ring itself instead - an experimental extension bypassing avail and used ring completely Typical use: sh run-on-all.sh perf stat -r 10 --log-fd 1 -- ./ring It doesn't depend on the kernel directly, but it's handy to have as much virtio stuff as possible in one tree. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin
Родитель
fb9b050ce9
Коммит
481eaec37e
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@ -0,0 +1,22 @@
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all:
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all: ring virtio_ring_0_9 virtio_ring_poll
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CFLAGS += -Wall
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CFLAGS += -pthread -O2 -ggdb
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LDFLAGS += -pthread -O2 -ggdb
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main.o: main.c main.h
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ring.o: ring.c main.h
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virtio_ring_0_9.o: virtio_ring_0_9.c main.h
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virtio_ring_poll.o: virtio_ring_poll.c virtio_ring_0_9.c main.h
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ring: ring.o main.o
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virtio_ring_0_9: virtio_ring_0_9.o main.o
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virtio_ring_poll: virtio_ring_poll.o main.o
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clean:
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-rm main.o
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-rm ring.o ring
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-rm virtio_ring_0_9.o virtio_ring_0_9
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-rm virtio_ring_poll.o virtio_ring_poll
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.PHONY: all clean
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@ -0,0 +1,2 @@
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Partial implementation of various ring layouts, useful to tune virtio design.
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Uses shared memory heavily.
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@ -0,0 +1,366 @@
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/*
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* Copyright (C) 2016 Red Hat, Inc.
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* Author: Michael S. Tsirkin <mst@redhat.com>
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* This work is licensed under the terms of the GNU GPL, version 2.
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*
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* Command line processing and common functions for ring benchmarking.
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*/
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#define _GNU_SOURCE
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#include <getopt.h>
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#include <pthread.h>
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#include <assert.h>
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#include <sched.h>
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#include "main.h"
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#include <sys/eventfd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <limits.h>
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int runcycles = 10000000;
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int max_outstanding = INT_MAX;
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int batch = 1;
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bool do_sleep = false;
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bool do_relax = false;
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bool do_exit = true;
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unsigned ring_size = 256;
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static int kickfd = -1;
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static int callfd = -1;
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void notify(int fd)
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{
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unsigned long long v = 1;
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int r;
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vmexit();
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r = write(fd, &v, sizeof v);
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assert(r == sizeof v);
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vmentry();
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}
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void wait_for_notify(int fd)
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{
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unsigned long long v = 1;
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int r;
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vmexit();
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r = read(fd, &v, sizeof v);
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assert(r == sizeof v);
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vmentry();
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}
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void kick(void)
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{
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notify(kickfd);
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}
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void wait_for_kick(void)
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{
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wait_for_notify(kickfd);
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}
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void call(void)
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{
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notify(callfd);
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}
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void wait_for_call(void)
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{
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wait_for_notify(callfd);
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}
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void set_affinity(const char *arg)
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{
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cpu_set_t cpuset;
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int ret;
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pthread_t self;
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long int cpu;
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char *endptr;
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if (!arg)
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return;
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cpu = strtol(arg, &endptr, 0);
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assert(!*endptr);
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assert(cpu >= 0 || cpu < CPU_SETSIZE);
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self = pthread_self();
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CPU_ZERO(&cpuset);
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CPU_SET(cpu, &cpuset);
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ret = pthread_setaffinity_np(self, sizeof(cpu_set_t), &cpuset);
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assert(!ret);
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}
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static void run_guest(void)
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{
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int completed_before;
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int completed = 0;
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int started = 0;
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int bufs = runcycles;
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int spurious = 0;
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int r;
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unsigned len;
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void *buf;
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int tokick = batch;
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for (;;) {
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if (do_sleep)
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disable_call();
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completed_before = completed;
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do {
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if (started < bufs &&
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started - completed < max_outstanding) {
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r = add_inbuf(0, NULL, "Hello, world!");
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if (__builtin_expect(r == 0, true)) {
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++started;
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if (!--tokick) {
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tokick = batch;
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if (do_sleep)
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kick_available();
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}
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}
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} else
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r = -1;
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/* Flush out completed bufs if any */
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if (get_buf(&len, &buf)) {
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++completed;
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if (__builtin_expect(completed == bufs, false))
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return;
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r = 0;
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}
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} while (r == 0);
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if (completed == completed_before)
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++spurious;
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assert(completed <= bufs);
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assert(started <= bufs);
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if (do_sleep) {
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if (enable_call())
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wait_for_call();
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} else {
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poll_used();
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}
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}
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}
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static void run_host(void)
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{
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int completed_before;
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int completed = 0;
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int spurious = 0;
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int bufs = runcycles;
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unsigned len;
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void *buf;
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for (;;) {
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if (do_sleep) {
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if (enable_kick())
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wait_for_kick();
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} else {
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poll_avail();
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}
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if (do_sleep)
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disable_kick();
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completed_before = completed;
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while (__builtin_expect(use_buf(&len, &buf), true)) {
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if (do_sleep)
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call_used();
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++completed;
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if (__builtin_expect(completed == bufs, false))
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return;
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}
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if (completed == completed_before)
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++spurious;
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assert(completed <= bufs);
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if (completed == bufs)
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break;
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}
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}
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void *start_guest(void *arg)
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{
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set_affinity(arg);
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run_guest();
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pthread_exit(NULL);
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}
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void *start_host(void *arg)
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{
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set_affinity(arg);
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run_host();
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pthread_exit(NULL);
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}
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static const char optstring[] = "";
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static const struct option longopts[] = {
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{
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.name = "help",
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.has_arg = no_argument,
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.val = 'h',
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},
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{
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.name = "host-affinity",
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.has_arg = required_argument,
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.val = 'H',
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},
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{
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.name = "guest-affinity",
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.has_arg = required_argument,
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.val = 'G',
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},
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{
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.name = "ring-size",
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.has_arg = required_argument,
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.val = 'R',
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},
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{
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.name = "run-cycles",
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.has_arg = required_argument,
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.val = 'C',
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},
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{
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.name = "outstanding",
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.has_arg = required_argument,
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.val = 'o',
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},
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{
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.name = "batch",
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.has_arg = required_argument,
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.val = 'b',
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},
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{
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.name = "sleep",
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.has_arg = no_argument,
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.val = 's',
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},
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{
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.name = "relax",
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.has_arg = no_argument,
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.val = 'x',
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},
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{
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.name = "exit",
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.has_arg = no_argument,
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.val = 'e',
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},
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{
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}
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};
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static void help(void)
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{
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fprintf(stderr, "Usage: <test> [--help]"
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" [--host-affinity H]"
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" [--guest-affinity G]"
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" [--ring-size R (default: %d)]"
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" [--run-cycles C (default: %d)]"
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" [--batch b]"
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" [--outstanding o]"
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" [--sleep]"
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" [--relax]"
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" [--exit]"
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"\n",
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ring_size,
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runcycles);
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}
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int main(int argc, char **argv)
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{
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int ret;
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pthread_t host, guest;
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void *tret;
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char *host_arg = NULL;
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char *guest_arg = NULL;
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char *endptr;
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long int c;
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kickfd = eventfd(0, 0);
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assert(kickfd >= 0);
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callfd = eventfd(0, 0);
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assert(callfd >= 0);
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for (;;) {
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int o = getopt_long(argc, argv, optstring, longopts, NULL);
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switch (o) {
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case -1:
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goto done;
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case '?':
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help();
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exit(2);
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case 'H':
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host_arg = optarg;
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break;
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case 'G':
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guest_arg = optarg;
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break;
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case 'R':
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ring_size = strtol(optarg, &endptr, 0);
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assert(ring_size && !(ring_size & (ring_size - 1)));
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assert(!*endptr);
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break;
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case 'C':
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c = strtol(optarg, &endptr, 0);
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assert(!*endptr);
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assert(c > 0 && c < INT_MAX);
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runcycles = c;
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break;
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case 'o':
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c = strtol(optarg, &endptr, 0);
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assert(!*endptr);
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assert(c > 0 && c < INT_MAX);
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max_outstanding = c;
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break;
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case 'b':
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c = strtol(optarg, &endptr, 0);
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assert(!*endptr);
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assert(c > 0 && c < INT_MAX);
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batch = c;
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break;
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case 's':
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do_sleep = true;
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break;
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case 'x':
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do_relax = true;
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break;
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case 'e':
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do_exit = true;
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break;
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default:
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help();
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exit(4);
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break;
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}
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}
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/* does nothing here, used to make sure all smp APIs compile */
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smp_acquire();
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smp_release();
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smp_mb();
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done:
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if (batch > max_outstanding)
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batch = max_outstanding;
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if (optind < argc) {
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help();
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exit(4);
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}
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alloc_ring();
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ret = pthread_create(&host, NULL, start_host, host_arg);
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assert(!ret);
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ret = pthread_create(&guest, NULL, start_guest, guest_arg);
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assert(!ret);
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ret = pthread_join(guest, &tret);
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assert(!ret);
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ret = pthread_join(host, &tret);
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assert(!ret);
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return 0;
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}
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@ -0,0 +1,119 @@
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/*
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* Copyright (C) 2016 Red Hat, Inc.
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* Author: Michael S. Tsirkin <mst@redhat.com>
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* This work is licensed under the terms of the GNU GPL, version 2.
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*
|
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* Common macros and functions for ring benchmarking.
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*/
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#ifndef MAIN_H
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#define MAIN_H
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#include <stdbool.h>
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extern bool do_exit;
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|
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#if defined(__x86_64__) || defined(__i386__)
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#include "x86intrin.h"
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|
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static inline void wait_cycles(unsigned long long cycles)
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{
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unsigned long long t;
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|
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t = __rdtsc();
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while (__rdtsc() - t < cycles) {}
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}
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|
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#define VMEXIT_CYCLES 500
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#define VMENTRY_CYCLES 500
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|
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#else
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static inline void wait_cycles(unsigned long long cycles)
|
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{
|
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_Exit(5);
|
||||
}
|
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#define VMEXIT_CYCLES 0
|
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#define VMENTRY_CYCLES 0
|
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#endif
|
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|
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static inline void vmexit(void)
|
||||
{
|
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if (!do_exit)
|
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return;
|
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|
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wait_cycles(VMEXIT_CYCLES);
|
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}
|
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static inline void vmentry(void)
|
||||
{
|
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if (!do_exit)
|
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return;
|
||||
|
||||
wait_cycles(VMENTRY_CYCLES);
|
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}
|
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|
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/* implemented by ring */
|
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void alloc_ring(void);
|
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/* guest side */
|
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int add_inbuf(unsigned, void *, void *);
|
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void *get_buf(unsigned *, void **);
|
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void disable_call();
|
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bool enable_call();
|
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void kick_available();
|
||||
void poll_used();
|
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/* host side */
|
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void disable_kick();
|
||||
bool enable_kick();
|
||||
bool use_buf(unsigned *, void **);
|
||||
void call_used();
|
||||
void poll_avail();
|
||||
|
||||
/* implemented by main */
|
||||
extern bool do_sleep;
|
||||
void kick(void);
|
||||
void wait_for_kick(void);
|
||||
void call(void);
|
||||
void wait_for_call(void);
|
||||
|
||||
extern unsigned ring_size;
|
||||
|
||||
/* Compiler barrier - similar to what Linux uses */
|
||||
#define barrier() asm volatile("" ::: "memory")
|
||||
|
||||
/* Is there a portable way to do this? */
|
||||
#if defined(__x86_64__) || defined(__i386__)
|
||||
#define cpu_relax() asm ("rep; nop" ::: "memory")
|
||||
#else
|
||||
#define cpu_relax() assert(0)
|
||||
#endif
|
||||
|
||||
extern bool do_relax;
|
||||
|
||||
static inline void busy_wait(void)
|
||||
{
|
||||
if (do_relax)
|
||||
cpu_relax();
|
||||
else
|
||||
/* prevent compiler from removing busy loops */
|
||||
barrier();
|
||||
}
|
||||
|
||||
/*
|
||||
* Not using __ATOMIC_SEQ_CST since gcc docs say they are only synchronized
|
||||
* with other __ATOMIC_SEQ_CST calls.
|
||||
*/
|
||||
#define smp_mb() __sync_synchronize()
|
||||
|
||||
/*
|
||||
* This abuses the atomic builtins for thread fences, and
|
||||
* adds a compiler barrier.
|
||||
*/
|
||||
#define smp_release() do { \
|
||||
barrier(); \
|
||||
__atomic_thread_fence(__ATOMIC_RELEASE); \
|
||||
} while (0)
|
||||
|
||||
#define smp_acquire() do { \
|
||||
__atomic_thread_fence(__ATOMIC_ACQUIRE); \
|
||||
barrier(); \
|
||||
} while (0)
|
||||
|
||||
#endif
|
||||
|
|
@ -0,0 +1,272 @@
|
|||
/*
|
||||
* Copyright (C) 2016 Red Hat, Inc.
|
||||
* Author: Michael S. Tsirkin <mst@redhat.com>
|
||||
* This work is licensed under the terms of the GNU GPL, version 2.
|
||||
*
|
||||
* Simple descriptor-based ring. virtio 0.9 compatible event index is used for
|
||||
* signalling, unconditionally.
|
||||
*/
|
||||
#define _GNU_SOURCE
|
||||
#include "main.h"
|
||||
#include <stdlib.h>
|
||||
#include <stdio.h>
|
||||
#include <string.h>
|
||||
|
||||
/* Next - Where next entry will be written.
|
||||
* Prev - "Next" value when event triggered previously.
|
||||
* Event - Peer requested event after writing this entry.
|
||||
*/
|
||||
static inline bool need_event(unsigned short event,
|
||||
unsigned short next,
|
||||
unsigned short prev)
|
||||
{
|
||||
return (unsigned short)(next - event - 1) < (unsigned short)(next - prev);
|
||||
}
|
||||
|
||||
/* Design:
|
||||
* Guest adds descriptors with unique index values and DESC_HW in flags.
|
||||
* Host overwrites used descriptors with correct len, index, and DESC_HW clear.
|
||||
* Flags are always set last.
|
||||
*/
|
||||
#define DESC_HW 0x1
|
||||
|
||||
struct desc {
|
||||
unsigned short flags;
|
||||
unsigned short index;
|
||||
unsigned len;
|
||||
unsigned long long addr;
|
||||
};
|
||||
|
||||
/* how much padding is needed to avoid false cache sharing */
|
||||
#define HOST_GUEST_PADDING 0x80
|
||||
|
||||
/* Mostly read */
|
||||
struct event {
|
||||
unsigned short kick_index;
|
||||
unsigned char reserved0[HOST_GUEST_PADDING - 2];
|
||||
unsigned short call_index;
|
||||
unsigned char reserved1[HOST_GUEST_PADDING - 2];
|
||||
};
|
||||
|
||||
struct data {
|
||||
void *buf; /* descriptor is writeable, we can't get buf from there */
|
||||
void *data;
|
||||
} *data;
|
||||
|
||||
struct desc *ring;
|
||||
struct event *event;
|
||||
|
||||
struct guest {
|
||||
unsigned avail_idx;
|
||||
unsigned last_used_idx;
|
||||
unsigned num_free;
|
||||
unsigned kicked_avail_idx;
|
||||
unsigned char reserved[HOST_GUEST_PADDING - 12];
|
||||
} guest;
|
||||
|
||||
struct host {
|
||||
/* we do not need to track last avail index
|
||||
* unless we have more than one in flight.
|
||||
*/
|
||||
unsigned used_idx;
|
||||
unsigned called_used_idx;
|
||||
unsigned char reserved[HOST_GUEST_PADDING - 4];
|
||||
} host;
|
||||
|
||||
/* implemented by ring */
|
||||
void alloc_ring(void)
|
||||
{
|
||||
int ret;
|
||||
int i;
|
||||
|
||||
ret = posix_memalign((void **)&ring, 0x1000, ring_size * sizeof *ring);
|
||||
if (ret) {
|
||||
perror("Unable to allocate ring buffer.\n");
|
||||
exit(3);
|
||||
}
|
||||
event = malloc(sizeof *event);
|
||||
if (!event) {
|
||||
perror("Unable to allocate event buffer.\n");
|
||||
exit(3);
|
||||
}
|
||||
memset(event, 0, sizeof *event);
|
||||
guest.avail_idx = 0;
|
||||
guest.kicked_avail_idx = -1;
|
||||
guest.last_used_idx = 0;
|
||||
host.used_idx = 0;
|
||||
host.called_used_idx = -1;
|
||||
for (i = 0; i < ring_size; ++i) {
|
||||
struct desc desc = {
|
||||
.index = i,
|
||||
};
|
||||
ring[i] = desc;
|
||||
}
|
||||
guest.num_free = ring_size;
|
||||
data = malloc(ring_size * sizeof *data);
|
||||
if (!data) {
|
||||
perror("Unable to allocate data buffer.\n");
|
||||
exit(3);
|
||||
}
|
||||
memset(data, 0, ring_size * sizeof *data);
|
||||
}
|
||||
|
||||
/* guest side */
|
||||
int add_inbuf(unsigned len, void *buf, void *datap)
|
||||
{
|
||||
unsigned head, index;
|
||||
|
||||
if (!guest.num_free)
|
||||
return -1;
|
||||
|
||||
guest.num_free--;
|
||||
head = (ring_size - 1) & (guest.avail_idx++);
|
||||
|
||||
/* Start with a write. On MESI architectures this helps
|
||||
* avoid a shared state with consumer that is polling this descriptor.
|
||||
*/
|
||||
ring[head].addr = (unsigned long)(void*)buf;
|
||||
ring[head].len = len;
|
||||
/* read below might bypass write above. That is OK because it's just an
|
||||
* optimization. If this happens, we will get the cache line in a
|
||||
* shared state which is unfortunate, but probably not worth it to
|
||||
* add an explicit full barrier to avoid this.
|
||||
*/
|
||||
barrier();
|
||||
index = ring[head].index;
|
||||
data[index].buf = buf;
|
||||
data[index].data = datap;
|
||||
/* Barrier A (for pairing) */
|
||||
smp_release();
|
||||
ring[head].flags = DESC_HW;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
void *get_buf(unsigned *lenp, void **bufp)
|
||||
{
|
||||
unsigned head = (ring_size - 1) & guest.last_used_idx;
|
||||
unsigned index;
|
||||
void *datap;
|
||||
|
||||
if (ring[head].flags & DESC_HW)
|
||||
return NULL;
|
||||
/* Barrier B (for pairing) */
|
||||
smp_acquire();
|
||||
*lenp = ring[head].len;
|
||||
index = ring[head].index & (ring_size - 1);
|
||||
datap = data[index].data;
|
||||
*bufp = data[index].buf;
|
||||
data[index].buf = NULL;
|
||||
data[index].data = NULL;
|
||||
guest.num_free++;
|
||||
guest.last_used_idx++;
|
||||
return datap;
|
||||
}
|
||||
|
||||
void poll_used(void)
|
||||
{
|
||||
unsigned head = (ring_size - 1) & guest.last_used_idx;
|
||||
|
||||
while (ring[head].flags & DESC_HW)
|
||||
busy_wait();
|
||||
}
|
||||
|
||||
void disable_call()
|
||||
{
|
||||
/* Doing nothing to disable calls might cause
|
||||
* extra interrupts, but reduces the number of cache misses.
|
||||
*/
|
||||
}
|
||||
|
||||
bool enable_call()
|
||||
{
|
||||
unsigned head = (ring_size - 1) & guest.last_used_idx;
|
||||
|
||||
event->call_index = guest.last_used_idx;
|
||||
/* Flush call index write */
|
||||
/* Barrier D (for pairing) */
|
||||
smp_mb();
|
||||
return ring[head].flags & DESC_HW;
|
||||
}
|
||||
|
||||
void kick_available(void)
|
||||
{
|
||||
/* Flush in previous flags write */
|
||||
/* Barrier C (for pairing) */
|
||||
smp_mb();
|
||||
if (!need_event(event->kick_index,
|
||||
guest.avail_idx,
|
||||
guest.kicked_avail_idx))
|
||||
return;
|
||||
|
||||
guest.kicked_avail_idx = guest.avail_idx;
|
||||
kick();
|
||||
}
|
||||
|
||||
/* host side */
|
||||
void disable_kick()
|
||||
{
|
||||
/* Doing nothing to disable kicks might cause
|
||||
* extra interrupts, but reduces the number of cache misses.
|
||||
*/
|
||||
}
|
||||
|
||||
bool enable_kick()
|
||||
{
|
||||
unsigned head = (ring_size - 1) & host.used_idx;
|
||||
|
||||
event->kick_index = host.used_idx;
|
||||
/* Barrier C (for pairing) */
|
||||
smp_mb();
|
||||
return !(ring[head].flags & DESC_HW);
|
||||
}
|
||||
|
||||
void poll_avail(void)
|
||||
{
|
||||
unsigned head = (ring_size - 1) & host.used_idx;
|
||||
|
||||
while (!(ring[head].flags & DESC_HW))
|
||||
busy_wait();
|
||||
}
|
||||
|
||||
bool use_buf(unsigned *lenp, void **bufp)
|
||||
{
|
||||
unsigned head = (ring_size - 1) & host.used_idx;
|
||||
|
||||
if (!(ring[head].flags & DESC_HW))
|
||||
return false;
|
||||
|
||||
/* make sure length read below is not speculated */
|
||||
/* Barrier A (for pairing) */
|
||||
smp_acquire();
|
||||
|
||||
/* simple in-order completion: we don't need
|
||||
* to touch index at all. This also means we
|
||||
* can just modify the descriptor in-place.
|
||||
*/
|
||||
ring[head].len--;
|
||||
/* Make sure len is valid before flags.
|
||||
* Note: alternative is to write len and flags in one access -
|
||||
* possible on 64 bit architectures but wmb is free on Intel anyway
|
||||
* so I have no way to test whether it's a gain.
|
||||
*/
|
||||
/* Barrier B (for pairing) */
|
||||
smp_release();
|
||||
ring[head].flags = 0;
|
||||
host.used_idx++;
|
||||
return true;
|
||||
}
|
||||
|
||||
void call_used(void)
|
||||
{
|
||||
/* Flush in previous flags write */
|
||||
/* Barrier D (for pairing) */
|
||||
smp_mb();
|
||||
if (!need_event(event->call_index,
|
||||
host.used_idx,
|
||||
host.called_used_idx))
|
||||
return;
|
||||
|
||||
host.called_used_idx = host.used_idx;
|
||||
call();
|
||||
}
|
||||
|
|
@ -0,0 +1,24 @@
|
|||
#!/bin/sh
|
||||
|
||||
#use last CPU for host. Why not the first?
|
||||
#many devices tend to use cpu0 by default so
|
||||
#it tends to be busier
|
||||
HOST_AFFINITY=$(cd /dev/cpu; ls|grep -v '[a-z]'|sort -n|tail -1)
|
||||
|
||||
#run command on all cpus
|
||||
for cpu in $(cd /dev/cpu; ls|grep -v '[a-z]'|sort -n);
|
||||
do
|
||||
#Don't run guest and host on same CPU
|
||||
#It actually works ok if using signalling
|
||||
if
|
||||
(echo "$@" | grep -e "--sleep" > /dev/null) || \
|
||||
test $HOST_AFFINITY '!=' $cpu
|
||||
then
|
||||
echo "GUEST AFFINITY $cpu"
|
||||
"$@" --host-affinity $HOST_AFFINITY --guest-affinity $cpu
|
||||
fi
|
||||
done
|
||||
echo "NO GUEST AFFINITY"
|
||||
"$@" --host-affinity $HOST_AFFINITY
|
||||
echo "NO AFFINITY"
|
||||
"$@"
|
||||
|
|
@ -0,0 +1,316 @@
|
|||
/*
|
||||
* Copyright (C) 2016 Red Hat, Inc.
|
||||
* Author: Michael S. Tsirkin <mst@redhat.com>
|
||||
* This work is licensed under the terms of the GNU GPL, version 2.
|
||||
*
|
||||
* Partial implementation of virtio 0.9. event index is used for signalling,
|
||||
* unconditionally. Design roughly follows linux kernel implementation in order
|
||||
* to be able to judge its performance.
|
||||
*/
|
||||
#define _GNU_SOURCE
|
||||
#include "main.h"
|
||||
#include <stdlib.h>
|
||||
#include <stdio.h>
|
||||
#include <assert.h>
|
||||
#include <string.h>
|
||||
#include <linux/virtio_ring.h>
|
||||
|
||||
struct data {
|
||||
void *data;
|
||||
} *data;
|
||||
|
||||
struct vring ring;
|
||||
|
||||
/* enabling the below activates experimental ring polling code
|
||||
* (which skips index reads on consumer in favor of looking at
|
||||
* high bits of ring id ^ 0x8000).
|
||||
*/
|
||||
/* #ifdef RING_POLL */
|
||||
|
||||
/* how much padding is needed to avoid false cache sharing */
|
||||
#define HOST_GUEST_PADDING 0x80
|
||||
|
||||
struct guest {
|
||||
unsigned short avail_idx;
|
||||
unsigned short last_used_idx;
|
||||
unsigned short num_free;
|
||||
unsigned short kicked_avail_idx;
|
||||
unsigned short free_head;
|
||||
unsigned char reserved[HOST_GUEST_PADDING - 10];
|
||||
} guest;
|
||||
|
||||
struct host {
|
||||
/* we do not need to track last avail index
|
||||
* unless we have more than one in flight.
|
||||
*/
|
||||
unsigned short used_idx;
|
||||
unsigned short called_used_idx;
|
||||
unsigned char reserved[HOST_GUEST_PADDING - 4];
|
||||
} host;
|
||||
|
||||
/* implemented by ring */
|
||||
void alloc_ring(void)
|
||||
{
|
||||
int ret;
|
||||
int i;
|
||||
void *p;
|
||||
|
||||
ret = posix_memalign(&p, 0x1000, vring_size(ring_size, 0x1000));
|
||||
if (ret) {
|
||||
perror("Unable to allocate ring buffer.\n");
|
||||
exit(3);
|
||||
}
|
||||
memset(p, 0, vring_size(ring_size, 0x1000));
|
||||
vring_init(&ring, ring_size, p, 0x1000);
|
||||
|
||||
guest.avail_idx = 0;
|
||||
guest.kicked_avail_idx = -1;
|
||||
guest.last_used_idx = 0;
|
||||
/* Put everything in free lists. */
|
||||
guest.free_head = 0;
|
||||
for (i = 0; i < ring_size - 1; i++)
|
||||
ring.desc[i].next = i + 1;
|
||||
host.used_idx = 0;
|
||||
host.called_used_idx = -1;
|
||||
guest.num_free = ring_size;
|
||||
data = malloc(ring_size * sizeof *data);
|
||||
if (!data) {
|
||||
perror("Unable to allocate data buffer.\n");
|
||||
exit(3);
|
||||
}
|
||||
memset(data, 0, ring_size * sizeof *data);
|
||||
}
|
||||
|
||||
/* guest side */
|
||||
int add_inbuf(unsigned len, void *buf, void *datap)
|
||||
{
|
||||
unsigned head, avail;
|
||||
struct vring_desc *desc;
|
||||
|
||||
if (!guest.num_free)
|
||||
return -1;
|
||||
|
||||
head = guest.free_head;
|
||||
guest.num_free--;
|
||||
|
||||
desc = ring.desc;
|
||||
desc[head].flags = VRING_DESC_F_NEXT;
|
||||
desc[head].addr = (unsigned long)(void *)buf;
|
||||
desc[head].len = len;
|
||||
/* We do it like this to simulate the way
|
||||
* we'd have to flip it if we had multiple
|
||||
* descriptors.
|
||||
*/
|
||||
desc[head].flags &= ~VRING_DESC_F_NEXT;
|
||||
guest.free_head = desc[head].next;
|
||||
|
||||
data[head].data = datap;
|
||||
|
||||
#ifdef RING_POLL
|
||||
/* Barrier A (for pairing) */
|
||||
smp_release();
|
||||
avail = guest.avail_idx++;
|
||||
ring.avail->ring[avail & (ring_size - 1)] =
|
||||
(head | (avail & ~(ring_size - 1))) ^ 0x8000;
|
||||
#else
|
||||
avail = (ring_size - 1) & (guest.avail_idx++);
|
||||
ring.avail->ring[avail] = head;
|
||||
/* Barrier A (for pairing) */
|
||||
smp_release();
|
||||
#endif
|
||||
ring.avail->idx = guest.avail_idx;
|
||||
return 0;
|
||||
}
|
||||
|
||||
void *get_buf(unsigned *lenp, void **bufp)
|
||||
{
|
||||
unsigned head;
|
||||
unsigned index;
|
||||
void *datap;
|
||||
|
||||
#ifdef RING_POLL
|
||||
head = (ring_size - 1) & guest.last_used_idx;
|
||||
index = ring.used->ring[head].id;
|
||||
if ((index ^ guest.last_used_idx ^ 0x8000) & ~(ring_size - 1))
|
||||
return NULL;
|
||||
/* Barrier B (for pairing) */
|
||||
smp_acquire();
|
||||
index &= ring_size - 1;
|
||||
#else
|
||||
if (ring.used->idx == guest.last_used_idx)
|
||||
return NULL;
|
||||
/* Barrier B (for pairing) */
|
||||
smp_acquire();
|
||||
head = (ring_size - 1) & guest.last_used_idx;
|
||||
index = ring.used->ring[head].id;
|
||||
#endif
|
||||
*lenp = ring.used->ring[head].len;
|
||||
datap = data[index].data;
|
||||
*bufp = (void*)(unsigned long)ring.desc[index].addr;
|
||||
data[index].data = NULL;
|
||||
ring.desc[index].next = guest.free_head;
|
||||
guest.free_head = index;
|
||||
guest.num_free++;
|
||||
guest.last_used_idx++;
|
||||
return datap;
|
||||
}
|
||||
|
||||
void poll_used(void)
|
||||
{
|
||||
#ifdef RING_POLL
|
||||
unsigned head = (ring_size - 1) & guest.last_used_idx;
|
||||
|
||||
for (;;) {
|
||||
unsigned index = ring.used->ring[head].id;
|
||||
|
||||
if ((index ^ guest.last_used_idx ^ 0x8000) & ~(ring_size - 1))
|
||||
busy_wait();
|
||||
else
|
||||
break;
|
||||
}
|
||||
#else
|
||||
unsigned head = guest.last_used_idx;
|
||||
|
||||
while (ring.used->idx == head)
|
||||
busy_wait();
|
||||
#endif
|
||||
}
|
||||
|
||||
void disable_call()
|
||||
{
|
||||
/* Doing nothing to disable calls might cause
|
||||
* extra interrupts, but reduces the number of cache misses.
|
||||
*/
|
||||
}
|
||||
|
||||
bool enable_call()
|
||||
{
|
||||
unsigned short last_used_idx;
|
||||
|
||||
vring_used_event(&ring) = (last_used_idx = guest.last_used_idx);
|
||||
/* Flush call index write */
|
||||
/* Barrier D (for pairing) */
|
||||
smp_mb();
|
||||
#ifdef RING_POLL
|
||||
{
|
||||
unsigned short head = last_used_idx & (ring_size - 1);
|
||||
unsigned index = ring.used->ring[head].id;
|
||||
|
||||
return (index ^ last_used_idx ^ 0x8000) & ~(ring_size - 1);
|
||||
}
|
||||
#else
|
||||
return ring.used->idx == last_used_idx;
|
||||
#endif
|
||||
}
|
||||
|
||||
void kick_available(void)
|
||||
{
|
||||
/* Flush in previous flags write */
|
||||
/* Barrier C (for pairing) */
|
||||
smp_mb();
|
||||
if (!vring_need_event(vring_avail_event(&ring),
|
||||
guest.avail_idx,
|
||||
guest.kicked_avail_idx))
|
||||
return;
|
||||
|
||||
guest.kicked_avail_idx = guest.avail_idx;
|
||||
kick();
|
||||
}
|
||||
|
||||
/* host side */
|
||||
void disable_kick()
|
||||
{
|
||||
/* Doing nothing to disable kicks might cause
|
||||
* extra interrupts, but reduces the number of cache misses.
|
||||
*/
|
||||
}
|
||||
|
||||
bool enable_kick()
|
||||
{
|
||||
unsigned head = host.used_idx;
|
||||
|
||||
vring_avail_event(&ring) = head;
|
||||
/* Barrier C (for pairing) */
|
||||
smp_mb();
|
||||
#ifdef RING_POLL
|
||||
{
|
||||
unsigned index = ring.avail->ring[head & (ring_size - 1)];
|
||||
|
||||
return (index ^ head ^ 0x8000) & ~(ring_size - 1);
|
||||
}
|
||||
#else
|
||||
return head == ring.avail->idx;
|
||||
#endif
|
||||
}
|
||||
|
||||
void poll_avail(void)
|
||||
{
|
||||
unsigned head = host.used_idx;
|
||||
#ifdef RING_POLL
|
||||
for (;;) {
|
||||
unsigned index = ring.avail->ring[head & (ring_size - 1)];
|
||||
if ((index ^ head ^ 0x8000) & ~(ring_size - 1))
|
||||
busy_wait();
|
||||
else
|
||||
break;
|
||||
}
|
||||
#else
|
||||
while (ring.avail->idx == head)
|
||||
busy_wait();
|
||||
#endif
|
||||
}
|
||||
|
||||
bool use_buf(unsigned *lenp, void **bufp)
|
||||
{
|
||||
unsigned used_idx = host.used_idx;
|
||||
struct vring_desc *desc;
|
||||
unsigned head;
|
||||
|
||||
#ifdef RING_POLL
|
||||
head = ring.avail->ring[used_idx & (ring_size - 1)];
|
||||
if ((used_idx ^ head ^ 0x8000) & ~(ring_size - 1))
|
||||
return false;
|
||||
/* Barrier A (for pairing) */
|
||||
smp_acquire();
|
||||
|
||||
used_idx &= ring_size - 1;
|
||||
desc = &ring.desc[head & (ring_size - 1)];
|
||||
#else
|
||||
if (used_idx == ring.avail->idx)
|
||||
return false;
|
||||
|
||||
/* Barrier A (for pairing) */
|
||||
smp_acquire();
|
||||
|
||||
used_idx &= ring_size - 1;
|
||||
head = ring.avail->ring[used_idx];
|
||||
desc = &ring.desc[head];
|
||||
#endif
|
||||
|
||||
*lenp = desc->len;
|
||||
*bufp = (void *)(unsigned long)desc->addr;
|
||||
|
||||
/* now update used ring */
|
||||
ring.used->ring[used_idx].id = head;
|
||||
ring.used->ring[used_idx].len = desc->len - 1;
|
||||
/* Barrier B (for pairing) */
|
||||
smp_release();
|
||||
host.used_idx++;
|
||||
ring.used->idx = host.used_idx;
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
void call_used(void)
|
||||
{
|
||||
/* Flush in previous flags write */
|
||||
/* Barrier D (for pairing) */
|
||||
smp_mb();
|
||||
if (!vring_need_event(vring_used_event(&ring),
|
||||
host.used_idx,
|
||||
host.called_used_idx))
|
||||
return;
|
||||
|
||||
host.called_used_idx = host.used_idx;
|
||||
call();
|
||||
}
|
||||
|
|
@ -0,0 +1,2 @@
|
|||
#define RING_POLL 1
|
||||
#include "virtio_ring_0_9.c"
|
||||
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