Re: 2.6.21-mm1: many processes end up in D state

From: Jiri Slaby
Date: Mon Apr 30 2007 - 14:14:26 EST

On 4/30/07, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
On Mon, 30 Apr 2007 17:39:19 +0200
Jiri Slaby <jirislaby@xxxxxxxxx> wrote:

> Hi,
> I have a problem with higher disk loads (e.g. running git-log or yum update).
> Many processes end up in D state and system is unusable -- I'm not able to run
> anything but smooth mouse moving when this happens.
> If I wait for a 20-30sec it becomes usable. This happens in 2.6.21-rc7-mm2 and
> also in 2007-04-28-05-06 broken-out snapshot. I think 2.6.21-rc6-mm1 worked
> fine, but I'm uncertain. If it is important, let me know to re-test.

It is important, but I doubt if retesting 2.6.21-rc6-mm1 will clarify
things a lot.

Could you try switching to a different IO scheduler please? Anticipatory
would suit.

As I wrote below the sysrq-t, switch to noop didn't help, but it seems
that it's harder to reproduce with that:

<cite it's_bad_to_write_anything_below_logs="true">
Note that yum works on lvm on raid0 and git too, but on the another md volume.
Both ext3s. Drivers are sata_promise and ata_piix (sata disk); CFQ scheduler.
Using noop is no change (but seems to be harder to reproduce with it). I figured
out that it probably happens when 2+ processes are on both "processors" (HT on
P4) and are IO wait (multiload-applet shows red above the half).

Swap usage is 0 all the time.

Please keep a close eye on mainline, too. Wait for it to appear there :(

Ok, I'll try to play with that...

-- Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E
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