Possible Threading problem with -CURRENT / MySQL?

Jon Noack noackjr at alumni.rice.edu
Thu Jun 17 17:24:47 GMT 2004

On 06/17/04 08:00, Robert Watson wrote:
> On Thu, 17 Jun 2004, Jon Noack wrote:
>> On 06/17/04 01:07, Brad Knowles wrote:
>>> At 1:31 AM -0400 2004-06-17, Robert Watson wrote:
>>>> - Running with SCHED_4BSD instead of SCHED_ULE
>>> This is the only one that really concerns me.  This shows that we
>>>  clearly need more work on ULE.  Is there one particular thing
>>> that we seem to be tripping up on, or is it a multitude of
>>> things?
>> I think I'll switch to 4BSD until I see more work being done on ULE
>> (I read cvs-src as a hobby already so I'll know when to switch
>> back).  I noticed a performance drop from 5.2.1-p8 (with 4BSD) to
>> -CURRENT (with ULE) when I upgraded, but I attributed it to other
>> things.  However, the system still feels slower than before despite
>> having since disabled INVARIANTS, WITNESS, and userspace malloc
>> debugging flags.
> ULE seems to do a very good job of scheduling interactive tasks over
> other workloads, resulting in a very "snappy" feel on my boxes,
> despite heavy CPU load from background builds, etc.  The workload I
> looked at had no real "interactive" component, although it was a
> latency-centric RPC test, so timely hand-off as well as high
> throughput would be important.  I know that Jeff's measurement work
> on ULE had a substantial focus on deadlines -- whether or not ULE was
> timely in scheduling tasks, etc, and that he demonstrated that it was
> much stronger than most other available schedulers in this area.

Well, I switched to 4BSD and noticed this right away.  I occasionally 
get sound hiccups under heavy i/o with ULE [1], but with 4BSD it's a bit 
ridiculous.  There's a PR open about it (can't remember which off the 
top of my head), but sound will skip and slow down (play at half speed 
or slower).  I know the sound locking is not all it should be, so this 
may not be a representative test.  Regardless, my workstations are back 
on ULE...


[1] Often when using tar or bsdtar.  To reproduce:
cd /usr/ports/www/firefox; make extract

More information about the freebsd-current mailing list