Re: 2.5.65-mm4

["Martin J. Bligh" <mbligh@aracnet.com>]

>> profile from SDET 64:
> 
> SDET is rather irritating because a) nobody has a copy and b) we don't
> even know what it does.

Yeah, I know. sorry ... I'm trying to get aim7 done instead.

> and b) we don't even know what it does.

Lots of shell scripty stuff, I think.

>> 82303 __down
>> 42835 schedule
>> 31323 __wake_up
>> 26435 .text.lock.sched
>> 15924 .text.lock.transaction
> 
> But judging by this, it's a rebadged dbench.  The profile is identical.

Not sure what dbench does. But I'm probably doing lots of small reads
and writes inside pagecache.
 
> Note that the lock_kernel() contention has been drastically reduced and
> we're now hitting semaphore contention.
> 
> Running `dbench 32' on the quad Xeon, this patch took the context switch
> rate from 500/sec up to 125,000/sec.
> 
> I've asked Alex to put together a patch for spinlock-based locking in the
> block allocator (cut-n-paste from ext2).

OK, sounds like a plan. Made a huge impact for ext2, and might enable
us to actually be able to see the rest of it through the sem cloud.
 
> That will fix up lock_super(), but I suspect the main problem is the
> lock_journal() in journal_start().  I haven't thought about that one yet.

Thanks,

M.

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