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Date: Fri, 6 Feb 2009 10:58:07 +0000
From: Jarek Poplawski <jarkao2@gmail.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Miller <davem@davemloft.net>, zbr@ioremap.net, w@1wt.eu,
       dada1@cosmosbay.com, ben@zeus.com, mingo@elte.hu,
       linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
       jens.axboe@oracle.com
Subject: Re: [PATCH v2] tcp: splice as many packets as possible at once
Message-ID: <20090206105807.GD4879@ff.dom.local>
References: <20090202084358.GB4129@ff.dom.local> <20090202.235017.253437221.davem@davemloft.net> <20090203094108.GA4639@ff.dom.local> <20090205.235258.257422341.davem@davemloft.net> <20090206091034.GA4879@ff.dom.local> <20090206092326.GC6645@gondor.apana.org.au> <20090206095119.GC4879@ff.dom.local> <20090206102822.GB7175@gondor.apana.org.au>
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On Fri, Feb 06, 2009 at 09:28:22PM +1100, Herbert Xu wrote:
> On Fri, Feb 06, 2009 at 09:51:20AM +0000, Jarek Poplawski wrote:
> >
> > OK, but since there is not so much difference, and we need to waste
> > it in some cases anyway, plus handle it later some special way, I'm
> > a bit in doubt.
> 
> Well the thing is cards that don't support SG on tx probably
> don't support jumbo frames either.

?? I mean this 128 byte chunk would be hard to reuse after copying
to skb->data, and if reused, we could miss this for some NICs on TX,
so the whole packed would need a copy.

BTW, David mentioned something simple like sk_sndmsg_page would be
enough, but I guess not for these non-SG NICs. We have to allocate
bigger chunks for them, so more fragmentation to handle.

Cheers,
Jarek P.