Re: sluggish system responsiveness under higher IO load
From: Andrew Morton
Date: Sun Aug 06 2006 - 15:35:13 EST
On Sun, 6 Aug 2006 15:54:42 +0200
Matthias Dahl <mlkernel@xxxxxxxxxxxxxx> wrote:
> > I'd suggest that you generate a kernel profile while the sluggishness is
> > happening.
Please always do reply-to-all, especially on linux-kernel. I'm often two
days behind, sometimes five days.
> profile 1: (emerge of three huge packages which caused quite some IO)
> ffffffff803a0430 scsi_dispatch_cmd 459 0.7172
> ffffffff8026afda copy_user_generic_c 854 22.4737
> ffffffff80270e00 default_idle 49571 516.3646
> 0000000000000000 total 54590 0.0232
> profile 2: (emerge of recent kernel sources- huge, causes quite some IO too)
> ffffffff8020cae0 vm_normal_page 814 4.2396
> ffffffff8026ad70 copy_page 1929 8.6116
> ffffffff802075e0 unmap_vmas 2362 1.2726
> ffffffff80207d20 copy_page_range 2683 1.6938
> ffffffff80270e00 default_idle 45081 469.5938
> 0000000000000000 total 64216 0.0273
> I hope this helps.
Well, it rules a lot of things out. There's plenty of idle time there, so
that rules out a lot of silly things and points the finger at IO scheduler
bustage, poor page-replacement decisions, etc.
hm. Do you have any reason for thinking that it's specific to any
particular device driver or hardware setup?
How much memory does the machine have?
It'd be interesting if you could gather a `vmstat 1' trace during the
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