From: Jens Axboe <axboe@kernel.dk>
To: Alket Memushaj <amemushaj@gmail.com>
Cc: fio@vger.kernel.org
Subject: Re: dedupe and replay
Date: Sat, 27 Sep 2014 07:45:00 -0600 [thread overview]
Message-ID: <5426BF5C.9090301@kernel.dk> (raw)
In-Reply-To: <CA+BkS8MZ+TC=itWx4DSpRdqewhRNkNqSem08Em2KWBXWJ4DJMg@mail.gmail.com>
On 09/27/2014 05:19 AM, Alket Memushaj wrote:
> thanks for the quick response - but unfortunately this patch does not
> seem to have changed the result. I managed to get a 1.4:1 dedupe when
> setting dedupe_percentage to 99%. The test rig I have is like this: an
> array w/ inline dedupe @ 4K and I am the only user on it - I have a
> single machine mounting a single lun from the array (the whole space
> in the array is assigned to this lun). The synthetic test at
> dedupe_percentage=80 results in a 4:1 dedupe ratio from the array. The
> replay at 80% comes out as undedupable (ratio = 1.0:1) even with the
> latest patch. The replay generates about 1.7 million I/Os. ~1 million
> are 4K, 80 thousand are 8K, 70 thousand are 32K, etc... there's a
> decent number of I/O that is not a multiple of 4K, but the vast
> majority of the I/O is a multiple of 4K. The offset for each I/O is 4K
> aligned in the vast majority of I/Os.
(please don't top post)
I'll try with a trace replay here. If you can, would be nice to get your
trace.
--
Jens Axboe
next prev parent reply other threads:[~2014-09-27 13:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-26 18:30 dedupe and replay Alket Memushaj
2014-09-26 19:08 ` Jens Axboe
2014-09-26 19:38 ` Jens Axboe
2014-09-27 11:19 ` Alket Memushaj
2014-09-27 13:45 ` Jens Axboe [this message]
2014-09-27 14:02 ` Jens Axboe
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