Messages in this thread | | | Date | Thu, 8 Jan 2009 18:14:19 +0100 | From | Willy Tarreau <> | Subject | Re: Data corruption issue with splice() on 2.6.27.10 |
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On Thu, Jan 08, 2009 at 03:53:00PM +0100, Ingo Molnar wrote: > > * Willy Tarreau <w@1wt.eu> wrote: > > > On Thu, Jan 08, 2009 at 07:16:51AM +0000, Jarek Poplawski wrote: > > > On 06-01-2009 19:15, Willy Tarreau wrote: > > > ... > > > > Ah, so you might also have discovered a few annoyances with the API, eg > > > > the fact that splice() returns after the first read in non-blocking mode, > > > > as well as the fact that it never returns zero on close, but -EAGAIN, > > > > which requires an additional recv(MSG_PEEK) to distinguish between a > > > > close and a lack of data. But I leave that for a later discussion, let's > > > > address the corruption issue first. > > > > > > FYI, this should be just fixed: > > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=4f7d54f59bc470f0aaa932f747a95232d7ebf8b1 > > > > > > > Ah cool, thanks Jarek for notifying us. Indeed, it's the exact same patch > > I had pending here ;-) > > > > I'll ping Greg for a backport into -stable, as applications relying on > > this will clearly not work without that fix. > > > > The other one I had consists in removing "|| !timeo" at the end of the > > loop, because otherwise splice() returns very small chunks (typically > > 1448 or 1460 bytes), leading to disastrous performance on high bandwidth > > links. At 10 Gbps, this means about 800000 calls to splice() per second! > > looks interesting - would you mind to submit it?
OK I will. I preferred to focus on the bug first, which is clearly more annoying since it basically makes splice() unusuable in a proxy. I wanted to avoid changes before the bug is fixed, but now, with the first investigations, it seems that the fix will be in a different area anyway so that doesn't matter.
Regards, Willy
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