Date: Fri, 12 Oct 2001 10:32:53 -0500 (CDT) From: Mike Silbersack <silby@silby.com> To: Alfred Perlstein <bright@mu.org> Cc: <freebsd-current@freebsd.org> Subject: Re: Some interrupt coalescing tests Message-ID: <20011012102437.H29732-100000@achilles.silby.com> In-Reply-To: <20011012030519.N59854@elvis.mu.org>
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On Fri, 12 Oct 2001, Alfred Perlstein wrote: > > The network is 100mbps, switched. To simulate load, I used a syn flooder > > aimed at an unused port. icmp/rst response limiting was enabled. > > Actually, you might want to leave that on, it will generate more load. I considered leaving it on, but I'm not sure if that would be constructive or not. The primary problem with doing that is related to my test setup - as we see from the stable -> current attack, my current box couldn't take the interrupt load of that many incoming packets, which would slow down the outgoing packets. If I had a better test setup, I'd like to try that. > > Before: ~46000 ints/sec, 57-63% processor usage due to interrupts. > > After: ~38000 ints/sec, 50-60% processor usage due to interrupts. > > > > In both cases, the box felt responsive. > > You need to get real hardware to run these tests, obviously you aren't > saturating your line. I would suspect a better test would be to see > how many pps you get can at the point where cpu utlization reaches > 100%. Basically start at a base of 60,000pps, and see how many more > it takes to drive them both to 100%. > > Even your limited tests show a mean improvement of something like > 10%. > > 10% isn't earth shattering, but it is a signifigant improvement. Yes, there is some improvement, but I'm not sure that the actual effect is worthwhile. Even with the 10% decrease, you're still going to kill the box if the interrupt count goes much higher. If you can setup a 4.4+this patch test of some sort with varying loads to see the effect, maybe we could characterize the effect of the patch more. With my setup, I don't think I can really take this testing any further. Mike "Silby" Silbersack To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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