[WBEL-users] Memory issues - Machine goes into a swapping tailspin due to tooaggressive cacheing algorithm ?
Gary Mansell
Gary.Mansell@ricardo.com
Tue, 16 Mar 2004 16:25:21 +0000
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Dear all,
I have been using WBEL3.0 happily in a server environment for a while
now and I am now trying to use it on some desktops instead of RH9.0.
I seem to be bumping into a problem with WBEL being too aggressive with
it's cacheing. It would appear to cache data at the expense of making
applications use swap because there is no free memory. I only see this
problem on WBEL3.0 and not RH9.0.
I have applied the following kernel tweaks into /etc/sysctl.conf but
they do not seem to have fixed the problem:
#
# Fix for too aggressive file cacheing
#
vm.pagecache =3D 2 10 20
vm.inactive_clean_percent =3D 100
My application gets stuck into a swap frenzy and the machine grinds to a
halt.
Here is the output from cat /proc/meminfo:
[grma@shane 59] ~ > cat /proc/meminfo
total: used: free: shared: buffers: cached:
Mem: 525836288 445038592 80797696 0 31404032 187092992
Swap: 2146787328 30904320 2115883008
MemTotal: 513512 kB
MemFree: 78904 kB
MemShared: 0 kB
Buffers: 30668 kB
Cached: 181156 kB
SwapCached: 1552 kB
Active: 347540 kB
ActiveAnon: 204324 kB
ActiveCache: 143216 kB
Inact_dirty: 32452 kB
Inact_laundry: 27108 kB
Inact_clean: 5700 kB
Inact_target: 82560 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 513512 kB
LowFree: 78904 kB
SwapTotal: 2096472 kB
SwapFree: 2066292 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 4096 kB
My understanding of the "vm.pagecache =3D 2 10 20" tweak is that a =
maximum
of 20% of system memory should be used as file cache. Why is it then
that meminfo shows far more than this?
Is there anything that I can do to improve the performance of my apps?
Any help gratefully received.
Regards
--=20
Gary Mansell
Technical Computing Team Leader
IT Department
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ricardo Consulting Engineers Ltd.
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Dear all,<BR>
<BR>
I have been using WBEL3.0 happily in a server environment for a while =
now and I am now trying to use it on some desktops instead of RH9.0.<BR>
<BR>
I seem to be bumping into a problem with WBEL being too aggressive with =
it's cacheing. It would appear to cache data at the expense of making =
applications use swap because there is no free memory. I only see this =
problem on WBEL3.0 and not RH9.0.<BR>
<BR>
I have applied the following kernel tweaks into /etc/sysctl.conf but =
they do not seem to have fixed the problem:<BR>
<BR>
#<BR>
# Fix for too aggressive file cacheing<BR>
#<BR>
vm.pagecache =3D 2 10 20<BR>
vm.inactive_clean_percent =3D 100<BR>
<BR>
<BR>
My application gets stuck into a swap frenzy and the machine grinds to a =
halt.<BR>
<BR>
Here is the output from cat /proc/meminfo:<BR>
<BR>
[grma@shane 59] ~ > cat /proc/meminfo<BR>
total: =
used: free: shared: buffers: cached:<BR>
Mem: 525836288 445038592 =
80797696 0 31404032 =
187092992<BR>
Swap: 2146787328 30904320 2115883008<BR>
MemTotal: 513512 kB<BR>
MemFree: 78904 kB<BR>
MemShared: 0 =
kB<BR>
Buffers: 30668 kB<BR>
Cached: 181156 kB<BR>
SwapCached: 1552 kB<BR>
Active: 347540 kB<BR>
ActiveAnon: 204324 kB<BR>
ActiveCache: 143216 kB<BR>
Inact_dirty: 32452 kB<BR>
Inact_laundry: 27108 kB<BR>
Inact_clean: 5700 kB<BR>
Inact_target: 82560 kB<BR>
HighTotal: 0 =
kB<BR>
HighFree: &nbs=
p; 0 kB<BR>
LowTotal: 513512 kB<BR>
LowFree: 78904 kB<BR>
SwapTotal: 2096472 kB<BR>
SwapFree: 2066292 kB<BR>
HugePages_Total: 0<BR>
HugePages_Free: 0<BR>
Hugepagesize: 4096 kB<BR>
<BR>
<BR>
My understanding of the "vm.pagecache =3D 2 10 20" tweak is =
that a maximum of 20% of system memory should be used as file cache. Why =
is it then that meminfo shows far more than this?<BR>
<BR>
Is there anything that I can do to improve the performance of my =
apps?<BR>
<BR>
Any help gratefully received.<BR>
<BR>
Regards<BR>
<BR>
<TABLE CELLSPACING=3D"0" CELLPADDING=3D"0" WIDTH=3D"100%">
<TR>
<TD>
<PRE>--=20
Gary Mansell
Technical Computing Team Leader
IT Department
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ricardo Consulting Engineers Ltd.</PRE>
</TD>
</TR>
</TABLE>
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<BR><font size=3D1 font face=3D"arial" color=3Dnavy>This e-mail and any =
files transmitted with it are confidential and intended solely for the =
use of the individual or entity to=20
whom they are addressed.<BR>
If you have received this e-mail in error please notify the sender =
immediately and delete this e-mail from your system. Please note that =
any views<BR>
or opinions presented in this e-mail are solely those of the author and =
do not necessarily represent those of Ricardo (save for reports and =
other<BR>
documentation formally approved and signed for release to the intended =
recipient). Only Directors or Duly Authorised Officers are authorised to =
<BR>
enter into legally binding obligations on behalf of Ricardo unless the =
obligation is contained within a Ricardo Purchase Order. Ricardo may =
<BR>
monitor outgoing and incoming e-mails and other telecommunications on =
its e-mail and telecommuncations systems. By replying to this e-mail =
<BR>
you give consent to such monitoring. The recipient should check e-mail =
and any attachments for the presence of viruses. Ricardo accepts no <BR>
liability for any damage caused by any virus transmitted by this e-mail. =
"Ricardo" means Ricardo plc and its subsidiary companies.<BR>
Ricardo plc is a public limited company registered in England with =
registered number 00222915.<BR>
The registered office of Ricardo plc is Bridge Works,Shoreham-by Sea, =
West Sussex, BN43 5FG.</font><BR>
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