netdev - Re: [PATCH v2] tcp: splice as many packets as possible at once

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Message-ID: <20090203123338.GA9446@gondor.apana.org.au>
Date:	Tue, 3 Feb 2009 23:33:38 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Evgeniy Polyakov <zbr@...emap.net>
Cc:	david@...g.hm, Jarek Poplawski <jarkao2@...il.com>,
	David Miller <davem@...emloft.net>, w@....eu,
	dada1@...mosbay.com, ben@...s.com, mingo@...e.hu,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	jens.axboe@...cle.com
Subject: Re: [PATCH v2] tcp: splice as many packets as possible at once

On Tue, Feb 03, 2009 at 03:30:15PM +0300, Evgeniy Polyakov wrote:
>
> But we can proceed the discussion in case something interesting will
> appear. For example I can hack up e1000e driver to do a dumb copy of 9k
> each time it has received a jumbo frame and compare it with usual 1.5k
> MTU performance. But getting that modern CPUs are loafing with noticebly
> big IO chunks, this may only show that CPU was increased with the copy.
> But still may work.

Comparing performance is pointless because the only time you need
to do the copy is when the allocator has failed.  So there is *no*
alternative to copying, regardless of how slow it is.

You can always improve the allocator whether we do this copying
fallback or not.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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