svcrdma: Convert rdma_stat_recv to a per-CPU counter

Receives are frequent events. Avoid the overhead of a memory bus
lock cycle for counting a value that is hardly every used.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2020-12-29 15:47:44 -05:00
Родитель 59a00257c6
Коммит df971cd853
3 изменённых файлов: 54 добавлений и 7 удалений

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@ -49,6 +49,7 @@
#include <linux/sunrpc/rpc_rdma_cid.h>
#include <linux/sunrpc/svc_rdma_pcl.h>
#include <linux/percpu_counter.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
@ -65,7 +66,7 @@ extern unsigned int svcrdma_max_requests;
extern unsigned int svcrdma_max_bc_requests;
extern unsigned int svcrdma_max_req_size;
extern atomic_t rdma_stat_recv;
extern struct percpu_counter svcrdma_stat_recv;
extern atomic_t rdma_stat_read;
extern atomic_t rdma_stat_write;
extern atomic_t rdma_stat_sq_starve;

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@ -63,7 +63,7 @@ unsigned int svcrdma_max_req_size = RPCRDMA_DEF_INLINE_THRESH;
static unsigned int min_max_inline = RPCRDMA_DEF_INLINE_THRESH;
static unsigned int max_max_inline = RPCRDMA_MAX_INLINE_THRESH;
atomic_t rdma_stat_recv;
struct percpu_counter svcrdma_stat_recv;
atomic_t rdma_stat_read;
atomic_t rdma_stat_write;
atomic_t rdma_stat_sq_starve;
@ -110,6 +110,42 @@ static int read_reset_stat(struct ctl_table *table, int write,
return 0;
}
enum {
SVCRDMA_COUNTER_BUFSIZ = sizeof(unsigned long long),
};
static int svcrdma_counter_handler(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct percpu_counter *stat = (struct percpu_counter *)table->data;
char tmp[SVCRDMA_COUNTER_BUFSIZ + 1];
int len;
if (write) {
percpu_counter_set(stat, 0);
return 0;
}
len = snprintf(tmp, SVCRDMA_COUNTER_BUFSIZ, "%lld\n",
percpu_counter_sum_positive(stat));
if (len >= SVCRDMA_COUNTER_BUFSIZ)
return -EFAULT;
len = strlen(tmp);
if (*ppos > len) {
*lenp = 0;
return 0;
}
len -= *ppos;
if (len > *lenp)
len = *lenp;
if (len)
memcpy(buffer, tmp, len);
*lenp = len;
*ppos += len;
return 0;
}
static struct ctl_table_header *svcrdma_table_header;
static struct ctl_table svcrdma_parm_table[] = {
{
@ -149,10 +185,10 @@ static struct ctl_table svcrdma_parm_table[] = {
},
{
.procname = "rdma_stat_recv",
.data = &rdma_stat_recv,
.maxlen = sizeof(atomic_t),
.data = &svcrdma_stat_recv,
.maxlen = SVCRDMA_COUNTER_BUFSIZ,
.mode = 0644,
.proc_handler = read_reset_stat,
.proc_handler = svcrdma_counter_handler,
},
{
.procname = "rdma_stat_write",
@ -230,15 +266,26 @@ static void svc_rdma_proc_cleanup(void)
return;
unregister_sysctl_table(svcrdma_table_header);
svcrdma_table_header = NULL;
percpu_counter_destroy(&svcrdma_stat_recv);
}
static int svc_rdma_proc_init(void)
{
int rc;
if (svcrdma_table_header)
return 0;
rc = percpu_counter_init(&svcrdma_stat_recv, 0, GFP_KERNEL);
if (rc)
goto out_err;
svcrdma_table_header = register_sysctl_table(svcrdma_root_table);
return 0;
out_err:
return rc;
}
void svc_rdma_cleanup(void)

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@ -845,8 +845,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
}
list_del(&ctxt->rc_list);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
atomic_inc(&rdma_stat_recv);
percpu_counter_inc(&svcrdma_stat_recv);
svc_rdma_build_arg_xdr(rqstp, ctxt);