Re: Removing swap lockmap...

Stephen C. Tweedie (sct@redhat.com)
Wed, 20 Jan 1999 17:09:47 GMT


Hi,

On Tue, 19 Jan 1999 19:15:51 +0100 (CET), Andrea Arcangeli
<andrea@e-mind.com> said:

> On 19 Jan 1999, Zlatko Calusic wrote:
>> Yes, this case probably doesn't get enough testing with my current
>> setup, so it is quite hard (for me) to prove removing lockmap is
>> no-no. Problem is that I don't understand shm swapping very well

> Launch some time this proggy to try out shm swapping:

I have a shared memory stresser anyway if you want. However, when we
originally took out the lock map, it proved _very_ hard to reproduce the
race, and only a couple of people reported problems. Plain stress
testing with random access patterns over a day or more did not show up
the problem.

These races can be very nasty and hard to trigger. You really do need
to think the change through rather than just try-it-and-see.

--Stephen

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