Re: ext2 performance in 2.5.25 versus 2.4.19pre8aa2

[Andrew Morton <akpm@zip.com.au>]

Lincoln Dale wrote:
> 
> At 10:30 PM 14/07/2002 -0700, Andrew Morton wrote:
> >Funny thing about your results is the presence of sched_yield(),
> >especially in the copy-from-pagecache-only load.  That test should
> >peg the CPU at 100% and definitely shouldn't be spending time in
> >default_idle.  So who is calling sched_yield()?  I think it has to be
> >your test app?
> >
> >Be aware that the sched_yield() behaviour in 2.5 has changed a lot
> >wrt 2.4.  It has made StarOffice 5.2 completely unusable on a non-idle
> >system, for a start.  (This is a SO problem and not a kernel problem,
> >but it's a lesson).
> 
> my test app uses pthreads (one thread per disk-worker) and
> pthread_cond_wait in the master task to wait for all workers to finish.
> i'll switch the app to use clone() and sys_futex instead.

OK.

> i guess in that case, its debatable whether its a kernel problem or not --
> pthreads is out there, and if its default behavior is bad, any threaded app
> which uses it will also be bad.

Well if your machine is executing a single cycle in default_idle
with that load then there's a bug somewhere.

I took a quick look at glibc-linuxthreads but as usual, my brain
turned to mush and it took seven years off my life.

If you can send me a copy of your test app I'll take a look
at what's going on.

Thanks.