Re: anticipatory scheduling questions

From: Andrew Morton (akpm@digeo.com)
Date: Sat Mar 01 2003 - 05:40:24 EST


"Felipe Alfaro Solana" <felipe_alfaro@linuxmail.org> wrote:
>
> ----- Original Message -----
> > > It wasn't a typo... In fact, both deadline and AS give roughly the same
> > > timings (one second up or down). But I
> > > still don't understand why 2.5 is performing so much worse than 2.4.
> >
> > Me either. It's a bug.
> >
> > Does basic 2.5.63 do the same thing? Do you have a feel for when it started
> > happening?
>
> This has happened since the moment I switched from 2.4 to 2.5.63-mm1.

You have not actually said whether 2.5.63 base exhibits the same problem.
>From the vmstat traces it appears that the answer is "yes"?

> > > Could a "vmstat" or "iostat" dump be interesting?
> > 2.4 versus 2.5 would be interesting, yes.
>
> I have retested this with 2.4.20-2.54, 2.5.63 and 2.5.63-mm1...
> and have attached the files to this message

Thanks. Note how 2.4 is consuming a few percent CPU, whereas 2.5 is
consuming 100%. Approximately half of it system time.

It does appear that some change in 2.5 has caused evolution to go berserk
during this operation.

> (I think pasting them
> here would result in wrapping, making it harder to read).
>
> If you need more testing or benchmarking, ask for it :-)

Thanks for your patience.

The next step please is:

a) run top during the operation, work out which process is chewing all
   that CPU. Presumably it will be evolution or aspell

b) Do it again and this time run

        strace -p $(pidof evolution) # or aspell

This will tell us what it is up to.

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