Hardly :-)
On the hardware I have immediately available, I see no regressions wrt
performance. With instrumentation it's simple to demonstrate that most
of the queueing activity of an io heavy benchmark spends less time in
the kernel (most merging activity takes place outside of the queue lock,
hence queueing is lock free).
I've asked Ken to run this series on some of his big iron, I hope he'll
have some results for us soonish. I can run some pseudo benchmarks on a
4-way here with some simulated storage to demonstrate the locking
improvements.
I don't see 3/4 and 4/4 on lkml yet, I wonder if they got lost.
--
Jens Axboe
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