Bug 15193

Summary: kswapd continuously active
Product: IO/Storage Reporter: Rafael J. Wysocki (rjw)
Component: Block LayerAssignee: Jens Axboe (axboe)
Status: RESOLVED PATCH_ALREADY_AVAILABLE    
Severity: normal CC: marius, P
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 2.6.32.2 Tree: Mainline
Regression: Yes
Bug Depends on:    
Bug Blocks: 14230    

Description Rafael J. Wysocki 2010-01-31 22:50:57 UTC
Subject    : kswapd continuously active
Submitter  : Jan Engelhardt <jengelh@medozas.de>
Date       : 2010-01-22 23
References : http://marc.info/?l=linux-kernel&m=126420434519039&w=4
Handled-By : Jens Axboe <jens.axboe@oracle.com>

This entry is being used for tracking a regression from 2.6.31.  Please don't
close it until the problem is fixed in the mainline.
Comment 1 Jens Axboe 2010-02-12 12:59:57 UTC
Should be fixed by:

http://lkml.org/lkml/2010/2/12/41

which I hope will soon go in (for both .32 and .33).
Comment 2 Rafael J. Wysocki 2010-02-12 23:46:30 UTC
Patch : http://patchwork.kernel.org/patch/78856/
Handled-By : Jens Axboe <jens.axboe@oracle.com>
Comment 3 Marius Tolzmann 2010-06-24 09:32:32 UTC
Hi..

is this patch already applied to the mainline kernel?

we are currently having trouble with continuously running kswapds consuming up to 100% CPU time when the system is busy doing (heavy) I/O.

to reproduce:  dd if=/dev/zero of=somefile  will activate all kswapds when the file reaches the size of the installed memory (our systems have 8G up to 256G). (same effect on local reiserfs and local xfs)

In kernel 2.6.34 (and 2.6.35-rc3) this issue causes the system to become very very slow and unresponsive.

i don't want to file this as a new bug since our issue may be related to this bug?

regards, 
marius tolzmann
Comment 4 Pádraig Brady 2011-06-13 09:42:29 UTC
I'm seeing something very like this on 2.6.38.8-31.fc15.x86_64
on sandy bridge (dual core i3).

I've 3G RAM, 1.5G swap.
100% of the time when a file >= 2G is cached, kswapd0 will spin.
Uncaching the file by rm'ing it etc. will stop it from spinning.
It sometimes happens for files between 1.5G and 2G.

More details at https://bugzilla.redhat.com/show_bug.cgi?id=712019