Date: Fri, 26 Mar 2004 11:00:35 -0600 From: Jon Noack <noackjr@alumni.rice.edu> To: Kenneth Culver <culverk@sweetdreamsracing.biz> Cc: Dan Nelson <dnelson@allantgroup.com> Subject: Re: poor gigabit ethernet performance with amd64 + sk0 Message-ID: <406461B3.1090805@alumni.rice.edu> In-Reply-To: <20040326112153.wcgwk4o0wkwwosos@www.sweetdreamsracing.biz> References: <20040325220939.2ogcsoogkoookwwc@www.sweetdreamsracing.biz> <20040326153548.GD3446@dan.emsphone.com> <20040326112153.wcgwk4o0wkwwosos@www.sweetdreamsracing.biz>
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On 3/26/2004 10:21 AM, Kenneth Culver wrote: > Quoting Dan Nelson <dnelson@allantgroup.com>: >> In the last episode (Mar 25), Kenneth Culver said: >>> I recently did a short file transfer over gigabit ethernet in both >>> x86 and amd64. On x86 it appears the limiting factor is the laptop >>> I'm transferring to. I get about 20MB/sec to the laptop in x86. But >>> on amd64, I'm not sure what the limiting factor is, because I max out >>> at about 2.8MB/sec with the EXACT same hardware. Here are the dmesg >>> lines for that ethernet card: >> >> Make sure you're testing ethernet speeds and not disk speeds; try >> something like ttcp or tcpblast. Even a pII/600mhz can do 50MB/sec; >> any modern CPU should be able to do 90. You might also want to do a >> long test, then run systat -v to see if the CPU load or interrupts/sec >> is different between x86 and amd64 modes. > > I know for sure I'm not testing disk speeds, at least on the x86 side. > In x86 > the transfer at 20MB/sec is maxing out my laptop's hard drive. I have > the same > model hard drive running my amd64 -CURRENT as I do my x86 -CURRENT, and > both > kernels were built from the same source tree. The only difference I see > when > running the tests with systat -vm 1 is that sk0 is only interrupting around > 600-800 times per second on amd64, where it's interrupting at like 4000 > times > per second on x86, which is what I'd expect given that on FreeBSD-x86 I'm > sending data at 10x the speed of FreeBSD-amd64. > > One other thing I noticed while doing the systat -vm 1 was that the clk > device > is interrupting at over 1000 times per second instead of the x86'x 100 > times > per second. I could try changing that to 100 and see what happens. Also I'm > read a little bit in the NOTES file on amd64 that atpic is for legacy 8259A > interrupt controller support. I don't think I need that either. Could > any of > these be causing my problem? HZ=1024 by default on amd64, so you should be seeing approximately that many clk interrupts/second. Jon
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