From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: rick.jones2@hp.com, subramanian.vijay@gmail.com, netdev@vger.kernel.org
Subject: Re: [RFC] tcp: use order-3 pages in tcp_sendmsg()
Date: Fri, 21 Sep 2012 19:11:05 +0200 [thread overview]
Message-ID: <1348247465.2669.766.camel@edumazet-glaptop> (raw)
In-Reply-To: <20120921.130440.1881102470665263512.davem@davemloft.net>
On Fri, 2012-09-21 at 13:04 -0400, David Miller wrote:
> It's a silly limitation, in net/core/dev.c:
>
> /* Turn on no cache copy if HW is doing checksum */
> if (!(dev->flags & IFF_LOOPBACK)) {
> dev->hw_features |= NETIF_F_NOCACHE_COPY;
> if (dev->features & NETIF_F_ALL_CSUM) {
> dev->wanted_features |= NETIF_F_NOCACHE_COPY;
> dev->features |= NETIF_F_NOCACHE_COPY;
> }
> }
>
> Maybe this is probably better done as:
>
> /* Turn on no cache copy if HW is doing checksum */
> dev->hw_features |= NETIF_F_NOCACHE_COPY;
> if (!(dev->flags & IFF_LOOPBACK)) {
> if (dev->features & NETIF_F_ALL_CSUM) {
> dev->wanted_features |= NETIF_F_NOCACHE_COPY;
> dev->features |= NETIF_F_NOCACHE_COPY;
> }
> }
>
> And then the code matches more closely the comment. :-)
I did a test, and for various combinations (producer/consumer on same
core or not, same cpu or not...) and performance is divided by 2
So I guess we can leave the code as is
next prev parent reply other threads:[~2012-09-21 17:11 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-17 7:49 [RFC] tcp: use order-3 pages in tcp_sendmsg() Eric Dumazet
2012-09-17 16:12 ` David Miller
2012-09-17 17:02 ` Eric Dumazet
2012-09-17 17:04 ` Eric Dumazet
2012-09-17 17:07 ` David Miller
2012-09-19 15:14 ` Eric Dumazet
2012-09-19 17:28 ` Rick Jones
2012-09-19 17:55 ` Eric Dumazet
2012-09-19 17:56 ` David Miller
2012-09-19 19:04 ` Alexander Duyck
2012-09-19 20:18 ` Ben Hutchings
2012-09-19 22:20 ` Vijay Subramanian
2012-09-20 5:37 ` Eric Dumazet
2012-09-20 17:10 ` Rick Jones
2012-09-20 17:43 ` Eric Dumazet
2012-09-20 18:37 ` Yuchung Cheng
2012-09-20 19:40 ` David Miller
2012-09-20 20:06 ` Rick Jones
2012-09-20 20:25 ` Eric Dumazet
2012-09-21 15:48 ` Eric Dumazet
2012-09-21 16:27 ` David Miller
2012-09-21 16:51 ` Eric Dumazet
2012-09-21 17:04 ` David Miller
2012-09-21 17:11 ` Eric Dumazet [this message]
2012-09-23 12:47 ` Jan Engelhardt
2012-09-23 16:16 ` David Miller
2012-09-23 17:40 ` Jan Engelhardt
2012-09-23 18:13 ` Eric Dumazet
2012-09-23 18:27 ` David Miller
2012-09-20 21:39 ` Vijay Subramanian
2012-09-20 22:01 ` Rick Jones
2012-11-15 7:52 ` Yan, Zheng
2012-11-15 13:06 ` Eric Dumazet
2012-11-16 2:36 ` Yan, Zheng
2012-11-15 13:47 ` Eric Dumazet
2012-11-21 8:05 ` Yan, Zheng
2012-11-15 18:33 ` Rick Jones
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