From 6312fe77751f57d4fa2b28abeef84c6a95c28136 Mon Sep 17 00:00:00 2001 From: Li RongQing Date: Thu, 5 Jul 2018 14:34:32 +0800 Subject: [PATCH] net: limit each hash list length to MAX_GRO_SKBS After commit 07d78363dcff ("net: Convert NAPI gro list into a small hash table.")' there is 8 hash buckets, which allows more flows to be held for merging. but MAX_GRO_SKBS, the total held skb for merging, is 8 skb still, limit the hash table performance. keep MAX_GRO_SKBS as 8 skb, but limit each hash list length to 8 skb, not the total 8 skb Signed-off-by: Li RongQing Signed-off-by: David S. Miller --- include/linux/netdevice.h | 7 ++++- net/core/dev.c | 56 ++++++++++++++++----------------------- 2 files changed, 29 insertions(+), 34 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index f06ee8f91e74..b683971e500d 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -302,6 +302,11 @@ struct netdev_boot_setup { int __init netdev_boot_setup(char *str); +struct gro_list { + struct list_head list; + int count; +}; + /* * Structure for NAPI scheduling similar to tasklet but with weighting */ @@ -323,7 +328,7 @@ struct napi_struct { int poll_owner; #endif struct net_device *dev; - struct list_head gro_hash[GRO_HASH_BUCKETS]; + struct gro_list gro_hash[GRO_HASH_BUCKETS]; struct sk_buff *skb; struct hrtimer timer; struct list_head dev_list; diff --git a/net/core/dev.c b/net/core/dev.c index 7e6a2f66db5c..89825c1eccdc 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -149,7 +149,6 @@ #include "net-sysfs.h" -/* Instead of increasing this, you should create a hash table. */ #define MAX_GRO_SKBS 8 /* This should be increased if a protocol with a bigger head is added. */ @@ -5151,9 +5150,10 @@ out: return netif_receive_skb_internal(skb); } -static void __napi_gro_flush_chain(struct napi_struct *napi, struct list_head *head, +static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index, bool flush_old) { + struct list_head *head = &napi->gro_hash[index].list; struct sk_buff *skb, *p; list_for_each_entry_safe_reverse(skb, p, head, list) { @@ -5162,22 +5162,20 @@ static void __napi_gro_flush_chain(struct napi_struct *napi, struct list_head *h list_del_init(&skb->list); napi_gro_complete(skb); napi->gro_count--; + napi->gro_hash[index].count--; } } -/* napi->gro_hash contains packets ordered by age. +/* napi->gro_hash[].list contains packets ordered by age. * youngest packets at the head of it. * Complete skbs in reverse order to reduce latencies. */ void napi_gro_flush(struct napi_struct *napi, bool flush_old) { - int i; + u32 i; - for (i = 0; i < GRO_HASH_BUCKETS; i++) { - struct list_head *head = &napi->gro_hash[i]; - - __napi_gro_flush_chain(napi, head, flush_old); - } + for (i = 0; i < GRO_HASH_BUCKETS; i++) + __napi_gro_flush_chain(napi, i, flush_old); } EXPORT_SYMBOL(napi_gro_flush); @@ -5189,7 +5187,7 @@ static struct list_head *gro_list_prepare(struct napi_struct *napi, struct list_head *head; struct sk_buff *p; - head = &napi->gro_hash[hash & (GRO_HASH_BUCKETS - 1)]; + head = &napi->gro_hash[hash & (GRO_HASH_BUCKETS - 1)].list; list_for_each_entry(p, head, list) { unsigned long diffs; @@ -5257,27 +5255,13 @@ static void gro_pull_from_frag0(struct sk_buff *skb, int grow) } } -static void gro_flush_oldest(struct napi_struct *napi) +static void gro_flush_oldest(struct list_head *head) { - struct sk_buff *oldest = NULL; - unsigned long age = jiffies; - int i; + struct sk_buff *oldest; - for (i = 0; i < GRO_HASH_BUCKETS; i++) { - struct list_head *head = &napi->gro_hash[i]; - struct sk_buff *skb; + oldest = list_last_entry(head, struct sk_buff, list); - if (list_empty(head)) - continue; - - skb = list_last_entry(head, struct sk_buff, list); - if (!oldest || time_before(NAPI_GRO_CB(skb)->age, age)) { - oldest = skb; - age = NAPI_GRO_CB(skb)->age; - } - } - - /* We are called with napi->gro_count >= MAX_GRO_SKBS, so this is + /* We are called with head length >= MAX_GRO_SKBS, so this is * impossible. */ if (WARN_ON_ONCE(!oldest)) @@ -5292,6 +5276,7 @@ static void gro_flush_oldest(struct napi_struct *napi) static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb) { + u32 hash = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1); struct list_head *head = &offload_base; struct packet_offload *ptype; __be16 type = skb->protocol; @@ -5358,6 +5343,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff list_del_init(&pp->list); napi_gro_complete(pp); napi->gro_count--; + napi->gro_hash[hash].count--; } if (same_flow) @@ -5366,10 +5352,11 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff if (NAPI_GRO_CB(skb)->flush) goto normal; - if (unlikely(napi->gro_count >= MAX_GRO_SKBS)) { - gro_flush_oldest(napi); + if (unlikely(napi->gro_hash[hash].count >= MAX_GRO_SKBS)) { + gro_flush_oldest(gro_head); } else { napi->gro_count++; + napi->gro_hash[hash].count++; } NAPI_GRO_CB(skb)->count = 1; NAPI_GRO_CB(skb)->age = jiffies; @@ -6006,8 +5993,10 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi, hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED); napi->timer.function = napi_watchdog; napi->gro_count = 0; - for (i = 0; i < GRO_HASH_BUCKETS; i++) - INIT_LIST_HEAD(&napi->gro_hash[i]); + for (i = 0; i < GRO_HASH_BUCKETS; i++) { + INIT_LIST_HEAD(&napi->gro_hash[i].list); + napi->gro_hash[i].count = 0; + } napi->skb = NULL; napi->poll = poll; if (weight > NAPI_POLL_WEIGHT) @@ -6047,8 +6036,9 @@ static void flush_gro_hash(struct napi_struct *napi) for (i = 0; i < GRO_HASH_BUCKETS; i++) { struct sk_buff *skb, *n; - list_for_each_entry_safe(skb, n, &napi->gro_hash[i], list) + list_for_each_entry_safe(skb, n, &napi->gro_hash[i].list, list) kfree_skb(skb); + napi->gro_hash[i].count = 0; } }