Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()

[Linus Torvalds]

On Sun, Sep 13, 2015 at 4:12 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
>
> Really need to run these numbers on slower disks where block layer
> merging makes a difference to performance.

Yeah. We've seen plugging and io schedulers not make much difference
for high-performance flash (although I think the people who argued
that noop should generally be used for non-rotating media were wrong,
I think - the elevator ends up still being critical to merging, and
while merging isn't a life-or-death situation, it tends to still
help).

For rotating rust with nasty seek times, the plugging is likely to
make the biggest difference.

               Linus
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