Date: Fri, 19 Oct 2007 10:25:20 +0400 From: Alexey Popov <lol@chistydom.ru> To: Scott Long <scottl@samsco.org> Cc: Boris Samorodov <bsam@ipt.ru>, freebsd-hackers@freebsd.org, freebsd-stable@freebsd.org Subject: Re: amrd disk performance drop after running under high load Message-ID: <47184DD0.6050704@chistydom.ru> In-Reply-To: <4717D6BC.5090206@samsco.org> References: <47137D36.1020305@chistydom.ru> <47140906.2020107@FreeBSD.org> <47146FB4.6040306@chistydom.ru> <47147E49.9020301@FreeBSD.org> <47149E6E.9000500@chistydom.ru> <4715035D.2090802@FreeBSD.org> <4715C297.1020905@chistydom.ru> <4715C5D7.7060806@FreeBSD.org> <47165A01.1030806@chistydom.ru> <07289061@ipt.ru> <4717D6BC.5090206@samsco.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi Scott Long wrote: >>> interrupt total rate >>> irq6: fdc0 8 0 >>> irq14: ata0 47 0 >>> irq16: uhci0 1428187319 1851 >> ^^^^^^^^^^ ^^^^ [1] >>> irq18: uhci2 12374352 16 >>> irq23: ehci0 3 0 >>> irq46: amr0 11983237 15 >>> irq64: em0 1427141755 1850 >> ^^^^^^^^^^ ^^^^ [2] >>> cpu0: timer 1540896452 1997 >>> cpu1: timer 1542377798 1999 >>> Total 5962960971 7730 >> >> [1] and [2] looks suspicious to me (totals and rate are too close to >> each other and btw to timers). Let the latter (timers) alone. Do you >> use any USB device? Can you try to use other network card? That >> behaviour seems to be an interrupt storm and/or irq collision. > > It's neither. It's a side effect of a feature that FreeBSD abuses for > handling interrupts. Note that amr0 and ehci2 are acting similar. It's > mostly harmless, but it does waste CPU cycles. I wouldn't expect this > on a recent version of FreeBSD, though, at least not from the e1000 > driver. I have this effect on many servers and I believe it is harmless. At once I was trying to reduce CPU usage on the very loaded server and removed USB from kernel. This effect disappeared, but there was no significant difference in CPU usage. I disagree about your words about recent version. I have this effect on many servers with latest FreeBSD-6-stable and em. Actually I have more servers with this effect than without it. With best regards, Alexey Popov
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?47184DD0.6050704>