Date: Wed, 25 May 2005 18:44:37 +0200 From: Matthias Buelow <mkb@incubus.de> To: Kris Kennaway <kris@obsecurity.org> Cc: freebsd-stable@freebsd.org Subject: Re: Performance of 4.x vs 5.x (Re: Lifetime of FreeBSD branches) Message-ID: <4294AB75.9080908@incubus.de> In-Reply-To: <20050525053054.GA76491@xor.obsecurity.org> References: <20050524221454.GA56421@xor.obsecurity.org> <4293F4D9.90204@incubus.de> <84dead7205052420503fded0e9@mail.gmail.com> <4293FD27.90500@incubus.de> <20050525042706.GA60021@xor.obsecurity.org> <4294054C.9080207@incubus.de> <20050525050943.GA64320@xor.obsecurity.org> <42940A81.1030801@incubus.de> <20050525052214.GA76339@xor.obsecurity.org> <42940C87.5000705@incubus.de> <20050525053054.GA76491@xor.obsecurity.org>
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Kris Kennaway wrote: >>interrupt total rate >>irq1: atkbd0 586 0 >>irq13: npx0 1 0 >>irq14: ata0 94 0 >>irq17: wi0 54 0 >>irq20: fxp0 atapci1 62079 99 >>irq21: uhci0 ehci0 1 0 >>irq22: uhci1 1102 1 >>lapic0: timer 1246549 1994 >>lapic1: timer 1246427 1994 >>Total 2556893 4091 >>The only relevant conflict I could see is irc 20; but I had already >>tested that by removing fxp0 from the kernel. > > I wonder if USB is causing the problem all on its own..since that was > the culprit in other situations when it was being triggered by virtue > of interrupt sharing. Any chance you can try a non-USB mouse and > remove USB from your kernel? Ok, now USB (both uhci and ehci) is gone. The problem is still the same. vmstat -i: interrupt total rate irq1: atkbd0 1324 3 irq12: psm0 8562 21 irq13: npx0 1 0 irq14: ata0 94 0 irq17: wi0 381 0 irq20: fxp0 atapci1 61956 154 lapic0: timer 801433 1993 lapic1: timer 801292 1993 Total 1675043 4166 To be frank, I do not believe it's got anything to do with locking or interrupts. It somehow seems just like the scheduler is doing a bad job of balancing interactive processes vs. disk i/o. I've seen the same stuff for years on NetBSD (until they changed scheduling around 1.5 or so) and Linux (until 2.4 kernels). During that time FreeBSD didn't exhibit these symptoms and only in 5.x have I seen that kind of behaviour creep back in. Has the classic scheduler been changed somehow? Maybe I should try and see if the problem persists with the ULE scheduler? mkb.
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