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Re: [Xen-users] io scheduler



Gerd,

Just an FYI I'm tracking -unstable these days due to problems with xend hanging with too many requests to it... side note, because of this I'm using the CFQ scheduler and no more complaints from users regarding I/O wait and no panics related to CFQ (actually no panics at all, now we just need to ditch xend!).

Gerd Hoffmann wrote:
Anand wrote:

Just had a thought, since those changes are in the kernel files it,
can't we just compile the kernel off the unstable and then use that for
domU. This way disk io features would be available to in any version.

No, it's in the backend driver, thus you have to replace the dom0
kernel.  No protocol changes, so you can just drop-in the new kernel and
everything should work.

However can any developer or someone can confirm if this is ok ? And how
do we verify if the IO scheduler working ? from the host ? inside dom U ?

With the new dom0 kernel you'll have one kernel thread per virtual block
device.  This helps the I/O scheduler (which uses the PID to decide how
to group/queue requests) to do a better job.  It also allows you to
tweak the priorities using ionice (comes with recent util-linux versions).

cheers,

  Gerd


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