Red Hat Bugzilla – Bug 251617
pm-utils sets the VM background timeout to 300 milliseconds!
Last modified: 2015-03-04 20:19:06 EST
Description of problem:
the laptop-tools script sets the VM background write timeout to 30 milliseconds;
this is INSANE. It keeps the disk extremely busy, waking it up all the time,
negating any power savings that the VM caches give you, and it also really
really sucks for peformance.
Actually, no, it sets the timeout to 0.3 seconds, which is rather reasonable in
terms of "this data should be written to disk" while the computer is on AC power.
> # Set dirty page values
> echo $DIRTY_WRITEBACK > /proc/sys/vm/dirty_writeback_centisecs
> echo $DIRTY_EXPIRE > /proc/sys/vm/dirty_expire_centisecs
At least, that's what it does on an up-to-date Fedora 7.
you're right about the 300msec part...
but I strongly disagree about this being appropriate or reasonable....
The kernel default is 5 seconds and that is on the conservative side. .3
seconds destroys most of the IO clustering Linux will do to IO, hurting IO
performance significantly. .3 seconds keeps the disks and SATA from using
power save mode, costing more power. (And "more power use" is not just an
issue for machines on battery, it's *very* relevant to servers and even
That sounds really very wrong.
Peter Jones is ripping out the code upstream now, will be building new packages
once a new version is out.
Read ya, Phil
A new package for devel is available, that should fix this bug.
I assume this is fixed, please reopen in case it is not.