Bug 267297 - bad RAID disk performance
Summary: bad RAID disk performance
Status: RESOLVED INTENTIONAL
Alias: None
Product: solid
Classification: Unmaintained
Component: libsolid-udisks (show other bugs)
Version: unspecified
Platform: Gentoo Packages Linux
: NOR normal
Target Milestone: ---
Assignee: Lukáš Tinkl
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-02-28 12:42 UTC by wbrana
Modified: 2011-03-02 13:46 UTC (History)
1 user (show)

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Description wbrana 2011-02-28 12:42:58 UTC 
Version:           unspecified (using KDE 4.6.0) 
OS:                Linux

KDE is badly affecting performance of RAID10. 
dd is reading disk with speed 353 MB/s if system is booted with non-KDE e.g. IceWM.
If KDE is started, speed drops to approx. 180-190 MB/s. 
Any disk operations are obviously slower. 
Logout from KDE, don't restore speed.



Reproducible: Didn't try

Steps to Reproduce:
echo 3 > /proc/sys/vm/drop_caches
dd if=/dev/md2 of=/dev/null bs=4M count=128

Actual Results:  
128+0 records in
128+0 records out
536870912 bytes (537 MB) copied, 2.94772 s, 182 MB/s

Expected Results:  
128+0 records in
128+0 records out
536870912 bytes (537 MB) copied, 1.52247 s, 353 MB/s
Comment 1 Christoph Feck 2011-02-28 13:42:04 UTC 
Can you check with "top" if there are any KDE processes consuming CPU cycles?
Comment 2 wbrana 2011-02-28 14:04:46 UTC 
top is only process with non-zero CPU usage
Comment 3 wbrana 2011-03-01 16:52:27 UTC 
I found that one of following daemons, which are started by KDE, is causing it.
/usr/libexec/udisks-daemon
/usr/libexec/upowerd
/usr/libexec/polkitd
After renaming, perf drop doesn't happen.
Comment 4 Christoph Feck 2011-03-01 17:09:13 UTC 
Thanks for the update. Reassigning to solid developers for further inspection.
Comment 5 wbrana 2011-03-01 17:28:29 UTC 
There is possibly related kernel bug
https://bugzilla.kernel.org/show_bug.cgi?id=15241
Comment 6 Lukáš Tinkl 2011-03-02 13:46:38 UTC 
If it's udisks, you should really report it somewhere else :)