From: Zoltan Kiss <zoltan.kiss@citrix.com>
To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
<xen-devel@lists.xenproject.org>, <wei.liu2@citrix.com>,
<linux@eikelenboom.it>, <paul.durrant@citrix.com>,
<netdev@vger.kernel.org>, <david.vrabel@citrix.com>,
<davem@davemloft.net>
Subject: Re: [PATCH net RFC] xen-netback: Fix grant ref resolution in RX path
Date: Thu, 15 May 2014 11:14:25 +0100 [thread overview]
Message-ID: <53749381.7010301@citrix.com> (raw)
In-Reply-To: <1400142682.30687.3.camel@kazak.uk.xensource.com>
On 15/05/14 09:31, Ian Campbell wrote:
> On Wed, 2014-05-14 at 12:12 +0100, Zoltan Kiss wrote:
>>> The 'cleanup' of stale ubufs should be right after __pskb_pull_tail().
>> We can't fix every place in the kernel where frags might be changed,
>> especially with a netback specific stuff, so unfortunately that won't work
>
> Is it worth fixing up the ones in netback though so that the things
> injected into the stack are consistent when we hand them over? It would
> avoid some search overhead on the rx path at the other end I guess?
> Perhaps not significant though.
There are plans to remove that unconditional pull, as it damages
performance. It is better to use during checksum setup maybe_pull_tail,
and pull up whatever is needed for checksum setup (this is already done,
partially). A sensible netfront would send the header in the first slot
anyway, so netback won't pull, and it definitely won't pull the whole
first frag.
Regards,
Zoli
prev parent reply other threads:[~2014-05-15 10:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-13 14:31 [PATCH net RFC] xen-netback: Fix grant ref resolution in RX path Zoltan Kiss
2014-05-13 15:47 ` Ian Campbell
2014-05-13 20:18 ` Zoltan Kiss
2014-05-13 16:13 ` Eric Dumazet
2014-05-13 19:25 ` Sander Eikelenboom
2014-05-14 8:32 ` Ian Campbell
2014-05-14 13:37 ` David Vrabel
2014-05-14 11:12 ` Zoltan Kiss
2014-05-14 11:35 ` Eric Dumazet
2014-05-14 13:25 ` Zoltan Kiss
2014-05-14 16:40 ` Ian Campbell
2014-05-14 17:28 ` Sander Eikelenboom
2014-05-14 18:44 ` Zoltan Kiss
2014-05-15 8:41 ` Ian Campbell
2014-05-15 8:31 ` Ian Campbell
2014-05-15 10:14 ` Zoltan Kiss [this message]
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