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tun: align write-heavy flow entry members to a cache line 

tun flow entry 'updated' fields are written when receive
every packet. Thus if a flow is receiving packets from a
particular flow entry, it'll cause false-sharing with
all the other who has looked it up, so move it in its own
cache line

and update 'queue_index' and 'update' field only when
they are changed to reduce the cache false-sharing.

Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Wang Li <wangli39@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Li RongQing 2018-12-06 16:08:17 +08:00 committed by David S. Miller
parent 7a35a50df5
commit 83b1bc122c
1 changed files with 5 additions and 3 deletions
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8
drivers/net/tun.c
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@ -201,7 +201,7 @@ struct tun_flow_entry {
u32 rxhash;
u32 rps_rxhash;
int queue_index;
unsigned long updated;
unsigned long updated ____cacheline_aligned_in_smp;
};
#define TUN_NUM_FLOW_ENTRIES 1024
@ -539,8 +539,10 @@ static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
e = tun_flow_find(head, rxhash);
if (likely(e)) {
/* TODO: keep queueing to old queue until it's empty? */
e->queue_index = queue_index;
e->updated = jiffies;
if (e->queue_index != queue_index)
e->queue_index = queue_index;
if (e->updated != jiffies)
e->updated = jiffies;
sock_rps_record_flow_hash(e->rps_rxhash);
} else {
spin_lock_bh(&tun->lock);