Re: [PATCH 0/2] Reduce mmap_sem hold times during file backed pagefaults

From: Rik van Riel
Date: Fri Oct 01 2010 - 08:08:24 EST


On 10/01/2010 01:04 AM, Michel Lespinasse wrote:
Linus, I would appreciate your comments on this since you shot down the
previous proposal. I hope you'll find this approach is sane, but I would
be interested to hear if you have specific objections.

mmap_sem is very coarse grained (per process) and has long read-hold times
(disk latencies); this breaks down rapidly for workloads that use both
read and write mmap_sem acquires. This short patch series tries to reduce
mmap_sem hold times when faulting in file backed VMAs.

The changes make sense to me, but it would be good to know
what kind of benefits you have seen with these patches.

Especially performance numbers :)

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