Date: Sun, 20 Jun 2004 20:10:23 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: threads@FreeBSD.org Cc: current@FreeBSD.org Subject: calcru: negative time ... followed by freeze Message-ID: <Pine.NEB.3.96L.1040620200617.5500D-100000@fledge.watson.org>
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I've now seen the following scenario happen several times in the last few days while doing testing and benchmarking: I run a multi-threaded test, such as super-smack, that causes a moderately high system load. I then hit Ctrl-T or run top, or some other activity that forces calcru() to execute. I will not infrequently get an extremely hard hang -- can't get to DDB using serial break, etc. I don't remember it happening when using non-threaded apps, so I'm wondering if there's a poor interaction with KSE/scheduler/who knows what. 7:55PM up 6 mins, 2 users, load averages: 1.37, 0.91, 0.43 USER TTY FROM LOGIN@ IDLE WHAT root d0 - 7:55PM - w rwatson p0 cboss 7:50PM 2 super-smack select-key hippy# top calcru: negative time of 1834075 usec for pid 654 (super-smack) ca~~ In this case, I ran super-smack with the following parameters: hippy:/usr/tmp/super-smack> super-smack select-key.smack 15 1000 This generates 15 workers, which should cause mysql to spawn off threads as well. I'm running with stock libpthread on this system (slightly old) but an up-to-date kernel from CVS, GENERIC. Has anyone else seen this? Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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