Messages in this thread | | | Date | Thu, 10 Mar 2005 00:52:56 +0100 | From | Christian Schmid <> | Subject | Re: BUG: Slowdown on 3000 socket-machines tracked down |
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> Yes, 2.6.11. I have tuned max_backlog and some other TCP and networking > related settings to give more buffers etc to networking tasks. I have not > tried any significant disk-IO while doing these tests. > > I finally got my systems set up so I can run my WAN emulator at full 1Gbps: > > I am getting right at 986Mbps throughput with 30ms round-trip latency > (15ms in both directions). > > So, latency does not seem to be the problem either. > > I think the problem can be narrowed down to: > > 1) Non-optimal kernel network tunings on your server.
I used all the default-settings on 2.6.11
> 2) Disk-IO (my disk is small and slow compared to a 'real' server, not > sure I can > really test this side of things, and I have not tried as of yet.)
This doesnt explain the speed-up when I change lower_zone_protection from 0 to 1024. It also doesnt explain the slowdown on 2.6.11 compared to 2.6.10
> 3) Your clients have much more latency and/or don't have enough bandwidth > to fully load your server. Since you didn't answer before: I > assume you > do not have a reliable test bed and are just hoping that enough > clients connect > to do your benchmarking.
Yes I just wait until they connect. On the graph it only takes about 2 minutes until 3000 sockets are created again.
> 4) There is something strange with sendfile and/or your application's > coding.
I am not doing more than calling sendfile. There is nothing one can do wrong.
> My suggestion would be to eliminate these variables by coming up with a > repeatable > test bed, alternative traffic generators, WAN/Network emulators for > latency, etc.
The problem still is that 1) it speeds up immediately when lower_zone_protection is raised to 1024. This proves it is NOT a disk-bottleneck. And second: it got much worse with 2.6.11 and lower_zone_protection disappeared on 2.6.11
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