From: "Rob Mueller" <robm@fastmail.fm>
To: "Mark Hahn" <hahn@physics.mcmaster.ca>
Cc: <linux-kernel@vger.kernel.org>, "Jeremy Howard" <jhoward@fastmail.fm>
Subject: Re: Strange load spikes on 2.4.19 kernel
Date: Sun, 13 Oct 2002 16:34:21 +1000 [thread overview]
Message-ID: <113001c27282$93955eb0$1900a8c0@lifebook> (raw)
In-Reply-To: Pine.LNX.4.33.0210130202070.17395-100000@coffee.psychology.mcmaster.ca
We've just discovered that this is actually happening on another one of our
machines as well. This machine uses 2.4.18 kernel, ext3 and has 2 SCSI
drives and 2 IDE drives which hold the main user mailbox data. Also it's a
P3 with a completely different motherboard rather than an Athlon, so it
doesn't seem to be hardware related in that respect.
> well, it's conceivable that if something is blocking a bunch
> of procs, it would also block your shell and ps, so not show up.
> "vmstat 1" might work better, though it's munging plenty of
> /proc files so is hardly immune to that.
But the ps/shell would only use CPU time, and there's plenty of that
available. Unless it was something everything would block on... what could
that be? A spin lock or something? Some interrupt routine? Would that even
result in other processes being counted as blocked process?
Also Let me do a calculation, though I have no idea if this is right or
not...
a) the first item in the uptime output is 'system load average for the last
1 minute'
b) it seems to only update/recalculate every 5 seconds
c) it jumps from < 1 to 20 in 1 interval (eg 5 seconds)
This means that for it to jump from < 1 to 20 in 5 seconds, there must be on
average about 60/5 * 20 = 240 processes blocked over those 5 seconds waiting
for run time of some sort for the load to jump 20 points. Is that right?
> but it's worth asking: do you notice a hiccup other than by looking
> at the loadav? that is, suppose the loadav is simply miscalculated...
Well yes, there definitely does seem to be a performance hit on the whole
system when the load jumps, everything feels significantly more 'sluggish'
during the spikes is the best I can describe it right now...
Rob
next parent reply other threads:[~2002-10-13 6:30 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.33.0210130202070.17395-100000@coffee.psychology.mcmaster.ca>
2002-10-13 6:34 ` Rob Mueller [this message]
2002-10-13 7:01 ` Strange load spikes on 2.4.19 kernel Joseph D. Wagner
2002-10-13 7:01 ` David S. Miller
2002-10-13 7:49 ` Joseph D. Wagner
2002-10-13 7:50 ` David S. Miller
2002-10-13 8:16 ` Joseph D. Wagner
2002-10-13 8:13 ` David S. Miller
2002-10-13 8:40 ` Joseph D. Wagner
2002-10-13 8:45 ` David S. Miller
2002-10-13 8:48 ` Mike Galbraith
2002-10-13 8:48 ` David S. Miller
2002-10-13 8:51 ` William Lee Irwin III
2002-10-13 10:20 ` Ingo Molnar
2002-10-13 19:42 ` Rik van Riel
2002-10-16 21:00 ` Bill Davidsen
2002-10-13 8:59 ` Anton Blanchard
2002-10-13 9:26 ` William Lee Irwin III
2002-10-13 12:31 ` Marius Gedminas
2002-12-11 22:54 Steven Roussey
2002-12-11 23:09 ` Andrew Morton
2002-12-11 23:54 ` Steven Roussey
2002-12-12 0:13 ` Andrew Morton
2002-12-12 0:31 ` Steven Roussey
[not found] <113001c27282$93955eb0$1900a8c0@lifebook.suse.lists.linux.kernel>
[not found] ` <000001c27286$6ab6bc60$7443f4d1@joe.suse.lists.linux.kernel>
[not found] ` <20021013.000127.43007739.davem@redhat.com.suse.lists.linux.kernel>
2002-10-13 7:24 ` Andi Kleen
2002-10-13 7:21 ` David S. Miller
2002-10-13 11:47 ` Hugh Dickins
2002-10-13 18:29 ` Andrew Morton
[not found] <Pine.LNX.4.33.0210121605490.16179-100000@coffee.psychology.mcmaster.ca>
2002-10-13 0:49 ` Rob Mueller
[not found] <001401c2719b$9d45c4a0$53241c43@joe>
2002-10-12 6:54 ` Rob Mueller
-- strict thread matches above, loose matches on Subject: below --
2002-10-12 3:13 Joseph D. Wagner
2002-10-12 3:10 Joseph D. Wagner
2002-10-12 1:12 Rob Mueller
2002-10-12 1:25 ` Andrew Morton
2002-10-12 2:25 ` Rob Mueller
2002-10-12 3:07 ` Andrew Morton
2002-10-12 6:37 ` Rob Mueller
2002-10-12 6:44 ` Andrew Morton
2002-10-12 6:52 ` Rob Mueller
2002-10-12 7:00 ` Andrew Morton
2002-10-13 6:14 ` Rob Mueller
2002-10-13 7:27 ` Simon Kirby
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