Re: 2.6.14 kswapd eating too much CPU

[Jan Kasprzak <kas@fi.muni.cz>]

Andrew Morton wrote:
: Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
: >
: > It does seem to scan SLABs intensively:
: >
: It might be worth trying the below.  Mainly for the debugging check.
: 
	I have compiled a new kernel - 2.6.15-rc2 with the patch you
recommended and with the slab statistics patch Marcelo mentioned.
I have add the oprofile support, but apart from that it is the same
kernel. It seems that the kswapd system time peaks has disappeared,
or at least they are much lower - kswapd0 has eaten ~3 minutes from
11 hours of uptime (in one of my previous mails I found that it used
to be 117 minutes after ~10 hours of uptime). On my MRTG graphs
at http://www.linux.cz/stats/mrtg-rrd/cpu.html some _small_ peaks
can be seen at 15 minutes after every odd-numbered hour. I have booted
this kernel around 2am local time.

	I have no unusual error messages in dmesg output, so this must
be this part of the patch:

: +		/*
: +		 * Avoid risking looping forever due to too large nr value:
: +		 * never try to free more than twice the estimate number of
: +		 * freeable entries.
: +		 */
: +		if (shrinker->nr > max_pass * 2)
: +			shrinker->nr = max_pass * 2;

	The shrinker statistics displayed in /proc/slabinfo are
# egrep '^(inode|dentry)_cache' /proc/slabinfo
inode_cache         1338   1380    600    6    1 : tunables   54   27    8 : slabdata    230    230      0 : shrinker stat 261765504 16831100
dentry_cache       40195  49130    224   17    1 : tunables  120   60    8 : slabdata   2890   2890    204 : shrinker stat 57946368 28877600

-Yenya

-- 
| Jan "Yenya" Kasprzak  <kas at {fi.muni.cz - work | yenya.net - private}> |
| GPG: ID 1024/D3498839      Fingerprint 0D99A7FB206605D7 8B35FCDE05B18A5E |
| http://www.fi.muni.cz/~kas/    Journal: http://www.fi.muni.cz/~kas/blog/ |
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> for implementing software.                              --Linus Torvalds <
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