From: David Miller <davem@davemloft.net>
To: mirqus@gmail.com
Cc: bhutchings@solarflare.com, srk@ti.com, netdev@vger.kernel.org
Subject: Re: Adding Support for SG,GSO,GRO
Date: Thu, 09 Dec 2010 11:38:06 -0800 (PST) [thread overview]
Message-ID: <20101209.113806.71114756.davem@davemloft.net> (raw)
In-Reply-To: <AANLkTi=8zWMYWG0DU147B08nN7xcvwaB9Bpq9fE8_fBe@mail.gmail.com>
From: Michał Mirosław <mirqus@gmail.com>
Date: Thu, 9 Dec 2010 19:47:57 +0100
> Isn't that condition too broad? If the data could change after packet
> is submitted to the driver then results would be unpredictable and
> allow sending wrong data with correct (because hw-calculated)
> checksum.
They are intentionally like that, without question.
Otherwise we'd need to interlock with all application mapped,
filesystem, and other page writes while sending any page over the
network.
We absolutely do not want to have to freeze every page we try to send
via sendfile() or similar, the cost is just too high.
If the application or networked filesystem needs such synchronization,
it provides it for itself.
For example, SAMBA only uses sendfile() when the file has an op-lock
held on it.
The checksum requirement for using SG is not going away, so continuing
to discuss along the lines of removing that requirement is not a good
use of your time I don't think.
next prev parent reply other threads:[~2010-12-09 19:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-09 10:33 Adding Support for SG,GSO,GRO Govindarajan, Sriramakrishnan
2010-12-09 10:50 ` Eric Dumazet
2010-12-09 14:49 ` Govindarajan, Sriramakrishnan
2010-12-09 15:02 ` Ben Hutchings
2010-12-09 18:29 ` David Miller
2010-12-09 18:47 ` Michał Mirosław
2010-12-09 18:58 ` Ben Hutchings
2010-12-10 8:27 ` Michał Mirosław
2010-12-09 19:38 ` David Miller [this message]
2010-12-10 14:18 ` Michał Mirosław
2010-12-10 14:31 ` David Lamparter
2010-12-10 16:01 ` Michał Mirosław
2010-12-10 16:20 ` Ben Hutchings
2010-12-10 18:05 ` David Miller
2010-12-10 16:23 ` David Lamparter
2010-12-10 16:26 ` Eric Dumazet
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