Re: [Qemu-devel] [PATCH 0/2] Allocate mutiple clusters for VMDK I/O

[Ashijeet Acharya]

On Tue, 21 Mar 2017 at 13:21, Stefan Hajnoczi <address@hidden> wrote:

> On Sat, Mar 11, 2017 at 11:54 AM, Ashijeet Acharya
> <address@hidden> wrote:
> > This series optimizes the I/O performance of VMDK driver.
> >
> > Patch 1 makes the VMDK driver to allocate multiple clusters at once.
> Earlier
> > it used to allocate cluster by cluster which slowed down its performance
> to a
> > great extent.
> >
> > Patch 2 changes the metadata update code to update the L2 tables for
> multiple
> > clusters at once.
>
> This patch series is a performance optimization.  Benchmark results
> are required to justify optimizations.  Please include performance
> results in the next revision.
>
> A popular disk I/O benchmarking is fio (https://github.com/axboe/fio).
> I suggest a write-heavy workload with a large block size:
>
> $ cat fio.job
> [global]
> direct=1
> filename=/dev/vdb
> ioengine=libaio
> runtime=30
> ramp_time=5
>
> [job1]
> iodepth=4
> rw=randwrite
> bs=256k
> $ for i in 1 2 3 4 5; do fio --output=fio-$i.txt fio.job; done #
> WARNING: overwrites /dev/vdb
>
> It's good practice to run the benchmark several times because there is
> usually some variation between runs.  This allows you to check that
> the variance is within a reasonable range (5-10% on a normal machine
> that hasn't been specially prepared for benchmarking).


I ran a few write tests of 128M using qemu-io and the results showed the
time to drop to almost half, will those work? Although, I will also try to
use the tool you mentioned later today when I am free and include those
results as well.

Ashijeet

>
>
> Stefan
>