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Bug #4352

librbd: increased memory usage on bobtail vs argonaut (and with no caching)

Added by Josh Durgin about 11 years ago. Updated about 11 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
Target version:
-
% Done:

0%

Source:
Community (user)
Tags:
Backport:
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Pull request ID:
Crash signature (v1):
Crash signature (v2):

Description

On irc, t0rn reports increased memory usage with caching turned off, and with bobtail compared to argonaut:

(09:40:26 AM) t0rn: joshd1: that is correct, with rbd cache set to true (other settings default) i see less memory usage of the qemu process. For the test I just start a VM, with this loop: 'while true; do dd if=/dev/zero of=/dev/vdb bs=1M ; done' and watch the memory usage climb. Doing that I see more usage when caching is off
(09:41:11 AM) t0rn: where vdb is the rbd volume
(09:45:25 AM) t0rn: so far i've only ran the test for 24 hours each, and it does appear to flat line somewhat (http://tinypic.com/view.php?pic=2q3dkav&s=6) thats a graph showing the results of the above test, but with rbd cache disabled (argonaut vs bobtail)
(09:47:29 AM) t0rn: i'm not sure what memory overhead i should expect under normal circumstances from qemu-rbd setups over the instance allocated amounts. That graph was from a vm granted 512mb through qemu
(09:48:43 AM) joshd1: t0rn: those are with the same size cluster with images in the same pool?
(09:49:00 AM) t0rn: same cluster and pool yes. The only difference was the client librdb versions
(09:51:16 AM) t0rn: centos 6.2 , compiled from source: 1.) qemu 1.1.2 2.) librbd from  v0.56.3 (6eb7e15a4783b122e9b0c85ea9ba064145958aa5) 3.) libiscsi 1.5.0 4.) libvirt 1.0.1
(09:58:45 AM) t0rn: i built with gperftools-devel,gperftools-libs 2.0-3.el6.2 from http://code.google.com/p/gperftools i used nss-devel-3.12.10-17.el6_2 (stock centos package)

The attached graph shows bobtail vs argonaut with caching off.

qemu-rbd_memory.jpg View (91.6 KB) Josh Durgin, 03/05/2013 11:51 AM

Associated revisions

Revision 7c208d2f (diff)
Added by Josh Durgin about 11 years ago

common: reduce default in-memory logs for non-daemons

The default of 100000 can result in hundreds of MBs of extra memory
used. This was most obvious when using librbd with caching enabled,
since there was a dout(0) accidentally left in the ObjectCacher.

refs: #4352
backport: bobtail
Signed-off-by: Josh Durgin <>

Revision 6838b8db (diff)
Added by Josh Durgin about 11 years ago

common: reduce default in-memory logs for non-daemons

The default of 100000 can result in hundreds of MBs of extra memory
used. This was most obvious when using librbd with caching enabled,
since there was a dout(0) accidentally left in the ObjectCacher.

refs: #4352
backport: bobtail
Signed-off-by: Josh Durgin <>
(cherry picked from commit 7c208d2f8e3f28f4055a4ae51eceae892dcef1dc)

History

#1 Updated by Sage Weil about 11 years ago

  • Assignee set to Josh Durgin

just merged the fix for this into next. still needs to be cherry-picked to bobtail branch.

#2 Updated by Josh Durgin about 11 years ago

  • Status changed from New to 7

cherry-picked to bobtail.

#3 Updated by Josh Durgin about 11 years ago

  • Status changed from 7 to Resolved

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