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From Nick Dimiduk <ndimi...@gmail.com>
Subject Re: mmap() based BucketCache IOEngine
Date Mon, 16 Mar 2015 20:42:48 GMT
Yes please!

On Mon, Mar 16, 2015 at 12:43 PM, Zee Chen <zeocio@gmail.com> wrote:

> Of the existing BucketCache IOEngines, the FileIOEngine uses pread() to
> copy data from kernel space to user space. This is a good choice when the
> total working set size is much bigger than the available RAM and the
> latency is dominated by IO access. However, when the entire working set is
> small enough to fit in the RAM, using mmap() (and subsequent memcpy()) to
> move data from kernel space to user space is faster. I have run some short
> keyval gets tests and the results indicate a reduction of 2%-7% of kernel
> CPU on my system, depending on the load. On the gets, the latency
> histograms from mmap() are identical to those from pread(), but peak
> throughput is close to 40% higher.
> Already tested the patch at Flurry. Anyone interested in reviewing the
> patch?
> -Zee

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