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netvsc: prefetch the first incoming ring element 

In interrupt handler, prefetch the first incoming ring element
so that it is in cache by the time NAPI poll gets to it.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger 2017-07-24 10:57:27 -07:00 committed by David S. Miller
parent 37b9dfa0d8
commit 43bf99ce00
1 changed files with 7 additions and 1 deletions
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8
drivers/net/hyperv/netvsc.c
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@ -30,6 +30,7 @@
#include <linux/if_ether.h>
#include <linux/vmalloc.h>
#include <linux/rtnetlink.h>
#include <linux/prefetch.h>
#include <asm/sync_bitops.h>
@ -1265,10 +1266,15 @@ int netvsc_poll(struct napi_struct *napi, int budget)
void netvsc_channel_cb(void *context)
{
struct netvsc_channel *nvchan = context;
struct vmbus_channel *channel = nvchan->channel;
struct hv_ring_buffer_info *rbi = &channel->inbound;
/* preload first vmpacket descriptor */
prefetch(hv_get_ring_buffer(rbi) + rbi->priv_read_index);
if (napi_schedule_prep(&nvchan->napi)) {
/* disable interupts from host */
hv_begin_read(&nvchan->channel->inbound);
hv_begin_read(rbi);
__napi_schedule(&nvchan->napi);
}