Re: [RFC PATCH 0/6] Convert all tasklets to workqueues

["Dan Williams" <dan.j.williams@intel.com>]

On 6/28/07, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 28 Jun 2007, Dan Williams wrote:
> > >
> > Unfortunately setting the thread to real time priority makes
> > throughput slightly worse.  Instead of floating around 35MB/s the
> > resync speed is stuck around 30MB/s:
>
> That is really strange. If you higher the prio of the work queue it
> gets worst?  Something really strange is happening here?  Are you using
> CONFIG_PREEMPT?
Everything thus far has been CONFIG_PREEMPT=n (the default for this platform).

With CONFIG_PREEMPT=y the resync is back in the 50MB/s range.

[iop-adma: hi-prio workqueue, CONFIG_PREEMPT=y]
iq81340mc:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md0 : active raid5 sdd[4] sdc[2] sdb[1] sda[0]
     468872448 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]
     [=>...................]  recovery =  5.8% (9136404/156290816)
finish=46.1min speed=53161K/sec

The tasklet configuration stays in 50MB/s ballpark, and the default
priority (nice -5) workqueue case remains in the 30's with
CONFIG_PREEMPT=n.

--
Dan
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