Lockless page cache test results

[Jens Axboe <axboe@suse.de>]

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Hi,

Running a splice benchmark on a 4-way IPF box, I decided to give the
lockless page cache patches from Nick a spin. I've attached the results
as a png, it pretty much speaks for itself.

The test in question splices a 1GiB file to a pipe and then splices that
to some output. Normally that output would be something interesting, in
this case it's simply /dev/null. So it tests the input side of things
only, which is what I wanted to do here. To get adequate runtime, the
operation is repeated a number of times (120 in this example). The
benchmark does that number of loops with 1, 2, 3, and 4 clients each
pinned to a private CPU. The pinning is mainly done for more stable
results.

-- 
Jens Axboe


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