Re: anticipatory scheduling questions

From: Ed Tomlinson (tomlins@cam.org)
Date: Sat Mar 01 2003 - 07:48:45 EST


Andrew Morton wrote:

> "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.

It might also help to know the filesystem(s) being used.

Ed Tomlinson
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