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Old 05-18-2009, 11:11 AM   #1
robzane
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kernel scheduler


I use a ramdisk. I would like to set scheduler elevator=noop for the ramdisk but I want to use another scheduler for the hard disks.
I can't understand if it is possible and how to do
Thank You

Please correct my English because I'm Italian
 
Old 05-18-2009, 07:10 PM   #2
unSpawn
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As far as I read /usr/src/kernels/${KERNELVERSION}/Documentation/scheduler/ only one scheduler can be selected and it only "works" on CPU's/groups/cgroups.
 
Old 05-18-2009, 09:00 PM   #3
Tinkster
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Quote:
Originally Posted by robzane View Post
I use a ramdisk. I would like to set scheduler elevator=noop for the ramdisk but I want to use another scheduler for the hard disks.
That's actually not a scheduler, but an io-scheduler. Slightly
different beast.

Quote:
Originally Posted by robzane View Post
I can't understand if it is possible and how to do
Thank You
Yes, it can.
Assuming you have sysfs enabled, with SCHEDNAME="your scheduler of
choice" and DEV is the name of the device you want to set an IO-
Scheduler for:
echo SCHEDNAME > /sys/block/DEV/queue/scheduler


Quote:
Originally Posted by robzane View Post
Please correct my English because I'm Italian
Your English is ultimately superior to my Italian ;}

In the second block you'd use whether instead of if.


Ciao,
Tink

Last edited by Tinkster; 05-18-2009 at 11:00 PM. Reason: blonde moment
 
Old 05-19-2009, 02:22 AM   #4
unSpawn
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Awesome. Learnt something new. Thanks Tink.
 
Old 05-20-2009, 12:23 AM   #5
robzane
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there is no queue/scheduler entry in /sys/block/ram0/
 
Old 05-20-2009, 01:40 AM   #6
Tinkster
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Goes to show I never looked at ram-disks, huh. I'd need to
start digging through kernel-doco to see WHY ram (and loop,
for that matter) devices don't have I/O schedulers attached.

But I guess you're out of luck with elevator and RAM disks
then. Sorry mate.

I'm still curious - what are you trying to do with that RAM
disk, and why the need for a different scheduler?



Cheers,
Tink
 
Old 05-21-2009, 12:51 AM   #7
robzane
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A different scheduler (=a direct io scheduler) reduce power consumption in ram and it is faster
I use 2gb ram disk for torrent
 
  


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