* [PATCH] ipv4: Cache local output routes
@ 2012-08-13 6:09 Yan, Zheng
2012-08-14 21:47 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Yan, Zheng @ 2012-08-13 6:09 UTC (permalink / raw)
To: netdev@vger.kernel.org, davem@davemloft.net; +Cc: Shi, Alex
Commit caacf05e5ad1abf causes big drop of UDP loop back performance.
The cause of the regression is that we do not cache the local output
routes. Each time we send a datagram from unconnected UDP socket,
the kernel allocates a dst_entry and adds it to the rt_uncached_list.
It creates lock contention on the rt_uncached_lock.
Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index e4ba974..fd9ecb5 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2028,7 +2028,6 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4)
}
dev_out = net->loopback_dev;
fl4->flowi4_oif = dev_out->ifindex;
- res.fi = NULL;
flags |= RTCF_LOCAL;
goto make_route;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ipv4: Cache local output routes
2012-08-13 6:09 [PATCH] ipv4: Cache local output routes Yan, Zheng
@ 2012-08-14 21:47 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2012-08-14 21:47 UTC (permalink / raw)
To: zheng.z.yan; +Cc: netdev, alex.shi
From: "Yan, Zheng" <zheng.z.yan@intel.com>
Date: Mon, 13 Aug 2012 14:09:59 +0800
> Commit caacf05e5ad1abf causes big drop of UDP loop back performance.
> The cause of the regression is that we do not cache the local output
> routes. Each time we send a datagram from unconnected UDP socket,
> the kernel allocates a dst_entry and adds it to the rt_uncached_list.
> It creates lock contention on the rt_uncached_lock.
>
> Reported-by: Alex Shi <alex.shi@intel.com>
> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
I was pretty sure not using 'fi' was necessary for semantic
reasons here, but I can't find any such requirement, so I've
applied this, thanks.
^ permalink raw reply [flat|nested] 2+ messages in thread
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