Messages in this thread | | | Date | Thu, 08 Jan 2009 15:16:16 +0000 | From | Ben Mansell <> | Subject | Re: Data corruption issue with splice() on 2.6.27.10 |
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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?
FWIW, I've also tested this change with some splice() benchmarks. I can confirm that removing the "|| !timeo" works well and improves performance significantly.
Ben
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