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

From: Duncan Sands (
Date: Tue Oct 08 2002 - 06:38:50 EST

> 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").

All the best,

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