Thread Scheduling

stheg olloydson stheg_olloydson at
Thu Jan 20 21:49:00 PST 2005

it was said:


>My question is, will I notice any performance improvement by using the
>new scheduler opposed to the 4.4BSD scheduler on an SMP system and can
>the new scheduler be utilized on a single processor system?  The
>intended use of the SMP system is for MySQL databases only.



I asked about the new scheduler on the performance list. Below is
(posted on list) reply:

>FWIW, one of the reasons that there hasn't been as much 
>interest in SCHED_ULE lately is likely that several of the 
>features previously only present in SCHED_ULE are now also 
>present in SCHED_4BSD -- for example, making more effective 
>uses of IPIs in reducing latency during inter-process 
>communication across processors.  While SCHED_ULE does contain 
>a number of interesting things not present in SCHED_4BSD, the 
>4BSD scheduler has hardly gone un-improved in that time.  
>However, Jeff Robserson does seem to have picked up recently 
>on both VFS SMP locking and ULE.  The scheduler tracing and 
>visualization tools he committed a couple of weeks ago are 
>really quite neat tools.
>Robert N M Watson

So we'll just have to wait until ULE is fully baked to see which
scheduler is best for a given application. For a more definitive
answer, you may want to ask directly on the performance list.



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