Messages in this thread |  | | | Date | Mon, 07 Mar 2005 16:41:02 +1100 | | From | Nick Piggin <> | | Subject | Re: BUG: Slowdown on 3000 socket-machines tracked down |
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Willy Tarreau wrote: > On Mon, Mar 07, 2005 at 04:14:37PM +1100, Nick Piggin wrote: > > >>I think you would have better luck in reproducing this problem if you >>did the full sendfile thing. >> >>I think it is becoming disk bound due to page reclaim problems, which >>is causing the slowdown. >> >>In that case, writing the network only test would help to confirm the >>problem is not a networking one - so not useless by any means. > > > Not necessarily, Nick. I have written an HTTP testing tool which matches > the description of Ben's : non-blocking, single-threaded, no disk I/O, > etc... It works flawlessly under 2.4, and gives me random numbers in 2.6,
No you're right, I'm not 100% sure, so I'm definitely not saying Ben's test will be useless. Just that if it is not too hard to make one with sendfile, I think he should.
If he makes a network-only version and cannot reproduce the problems, that *doesn't* mean it is *not* a network problem. However if he reproduces the problem with a full sendfile version and not the network only one, then that is a better indicator... but I'm rambling.
> especially if I start some CPU activity on the system, I can get pauses > of up to 13 seconds without this tool doing anything !!! At first I > believed it was because of the scheduler, but it might also be related > to what is described here since I had somewhat the same setup (gigE, 1500, > thousands of sockets). I never had enough time to investigate more, so I > went back to 2.4. >
I have heard other complaints about this, and they are definitely related to the scheduler (not saying yours is, but it is very possible).
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