Re: [PATCH] Re: Shared memory shmat/dt not working well in 2.5.x

Zlatko Calusic
2002-10-08T15:05:02Z

Duncan Sands <baldrick@wanadoo.fr> writes:

>> I also observed that other application I use occasionally - LXR (Linux
>> source cross referencing tool) - takes much longer to generate xref
>> database (which is in Berkeley DB files). It works in three passes,
>> where the last one, when it dumps symbols into DB, is interesting. In
>> 2.4 it finishes quickly (it uses 100% CPU, then occasionally syncs the
>> databases - heavy write traffic for a second - then continues), but
>> 2.5 has problems with it (it stucks writing to disk all the time, CPU
>> usage is minimal and process progresses very slowly). Andrew, if
>> you're interested I can send you some numbers to describe the case
>> better.
>
> Hmmm, are you using ext3? Changes to the meaning of yield sometimes
> make fsync go very slowly. This problem has been around since 2.5.28,
> and hasn't yet been fixed (As for a fix, Andrew Morton said "I'll sit tight for
> the while, see where shed_yield() behaviour ends up").
>

Yes, it's an ext3 partition, ordered mode. I don't have ext2 compiled
into kernel anymore. :)

Hm, if it's a problem with fsync() then that could explain slight
Oracle slowdown, too, as I think that Oracle is a heavy user of
fsync. But I don't know that for sure. I'll investigate further..

Regards,
--
Zlatko