From: "Mathias Burén" <mathias.buren@gmail.com>
To: Roberto Spadim <roberto@spadim.com.br>
Cc: Shaohua Li <shli@kernel.org>, Holger Kiehl <Holger.Kiehl@dwd.de>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-raid <linux-raid@vger.kernel.org>,
neilb@suse.de, axboe@kernel.dk, vgoyal@redhat.com,
martin.petersen@oracle.com
Subject: Re: [patch v2 0/6] Add TRIM support for raid linear/0/1/10
Date: Wed, 21 Mar 2012 02:29:40 +0000 [thread overview]
Message-ID: <CADNH=7GQ-M4JwWVwt4bvgiovH_eFH9Ew=AGM8r5poc7S5UZ4iQ@mail.gmail.com> (raw)
In-Reply-To: <CABYL=TpzjJcg=P7Jtwcg3Pdido1H0_p13DC64o14b=4+_+dQ1Q@mail.gmail.com>
On 21 March 2012 02:24, Roberto Spadim <roberto@spadim.com.br> wrote:
> =/ well maybe with a sas disk it could be faster? maybe a pciexpress disk too?
>
> Em 20 de março de 2012 23:08, Shaohua Li <shli@kernel.org> escreveu:
>> 2012/3/20 Shaohua Li <shli@kernel.org>:
>>> 2012/3/20 Holger Kiehl <Holger.Kiehl@dwd.de>:
>>>> Hello,
>>>>
>>>>
>>>> On Tue, 20 Mar 2012, Shaohua Li wrote:
>>>>
>>>>> 2012/3/20 Holger Kiehl <Holger.Kiehl@dwd.de>:
>>>>>>
>>>>>> Hello,
>>>>>>
>>>>>>
>>>>>> On Fri, 16 Mar 2012, Shaohua Li wrote:
>>>>>>
>>>>>>> The patches add TRIM support for raid linear/0/1/10. I'll add TRIM
>>>>>>> support
>>>>>>> for
>>>>>>> raid 4/5/6 later. The implementation is pretty straightforward and
>>>>>>> self-explained.
>>>>>>>
>>>>>>> v1->v2:
>>>>>>> 1. fixed a checking issue
>>>>>>> 2. dropped discard request plug and replace it with no discard merege,
>>>>>>> because
>>>>>>> current SCSI layer can't handle discard request merge.
>>>>>>>
>>>>>> Have tested TRIM patches on three different systems with the following
>>>>>> hardware/ setup:
>>>>>>
>>>>>> 1) root mounted on a raid1 over two SAS SSD's (200GB) and /home
>>>>>> partition
>>>>>> on a raid0 over a fusionio ioDrive Duo. Is very new and seen very
>>>>>> little usage.
>>>>>>
>>>>>> 2) root and /home mounted on a raid0 over two Intel X25 Postville
>>>>>> (160GB) connected to a Intel P55 Express chipset. Has seen very
>>>>>> heavy usage for approx. 2 years.
>>>>>>
>>>>>> 3) root and /home mounted on a raid0 over three OCZ-VERTEX2 (120GB)
>>>>>> connected via ICH7 south bridge. Has seen mild usage for approx.
>>>>>> 1.5 years.
>>>>>>
>>>>>> Made the following observations when running my own benchmark which
>>>>>> copies around a lot of small files and deletes them. The benchmark on
>>>>>> all systems was always run only on the /home partition ie. on a raid0.
>>>>>>
>>>>>> For system 1) there is hardly any measurable differnce whether discard
>>>>>> is enabled or not (~29000 files per second).
>>>>>>
>>>>>> On system 2) the performance drops from 6500->3700 files per second,
>>>>>> but under normal usage one does not notice any difference.
>>>>>
>>>>> do you have the blktrace data when the benchmark is running, especially
>>>>> when doing file deletion. I'd like to check the latency of discard in this
>>>>> case.
>>>>>
>>>> It is uploaded on ftp://ftp.dwd.de/pub/afd/test/trim
>>> Thanks, I'll check it.
>> Thanks for the testing. The trace data is very helpful. In the intel
>> SSD, trace data
>> shows a discard request uses about 1 ~ 3 ms. The filesystem suffers from
>> fragmentation too, so lots of small discard requests. When ext4 starts doing
>> discard, it usually uses more than 1 minutes. That's too bad.
>> If just looking one disk's trace data, there are some extra latencies between
>> two discard requests. The combined trace data of two disks show the latency
>> comes from waiting for another disk, so nothing abnormal. I thought we could
>> do an optimization for this case in the future.
>> So in summary, discard from the SSDs is slow. When your filesystem is
>> fragmented, the performance will be terrible.
>>
>> Thanks,
>> Shaohua
>> --
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>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
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Not relevant.
Mathias
next prev parent reply other threads:[~2012-03-21 2:29 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-16 7:32 [patch v2 0/6] Add TRIM support for raid linear/0/1/10 Shaohua Li
2012-03-16 7:32 ` [patch v2 1/6] block: makes bio_split support bio without data Shaohua Li
2012-03-16 7:32 ` [patch v2 2/6] blk: dont allow discard request merge temporarily Shaohua Li
2012-03-20 16:21 ` Vivek Goyal
2012-03-21 1:22 ` Shaohua Li
2012-03-21 12:14 ` [patch 1/2]block: handle merged discard request Shaohua Li
2012-03-22 2:32 ` Martin K. Petersen
2012-03-22 2:39 ` Shaohua Li
2012-03-22 2:53 ` Martin K. Petersen
2012-06-20 8:57 ` Christoph Hellwig
2012-06-22 3:46 ` Martin K. Petersen
2012-08-03 2:10 ` Shaohua Li
2012-08-18 3:06 ` Mike Snitzer
2012-08-18 3:47 ` Martin K. Petersen
2012-08-20 13:57 ` Mike Snitzer
2012-08-20 13:58 ` Christoph Hellwig
2012-08-20 14:12 ` Mike Snitzer
2012-08-20 14:15 ` Christoph Hellwig
2012-03-22 2:18 ` [patch v2 2/6] blk: dont allow discard request merge temporarily Martin K. Petersen
2012-03-22 2:33 ` Shaohua Li
2012-03-22 6:28 ` Christoph Hellwig
2012-03-16 7:32 ` [patch v2 3/6] md: linear supports TRIM Shaohua Li
2012-03-16 7:32 ` [patch v2 4/6] md: raid 0 " Shaohua Li
2012-03-16 7:32 ` [patch v2 5/6] md: raid 1 " Shaohua Li
2012-03-16 7:32 ` [patch v2 6/6] md: raid 10 " Shaohua Li
2012-03-19 19:38 ` [patch v2 0/6] Add TRIM support for raid linear/0/1/10 Holger Kiehl
2012-03-20 1:27 ` Shaohua Li
2012-03-20 9:50 ` Holger Kiehl
2012-03-20 12:09 ` Shaohua Li
2012-03-21 2:08 ` Shaohua Li
2012-03-21 2:24 ` Roberto Spadim
2012-03-21 2:29 ` Mathias Burén [this message]
2012-03-21 2:29 ` Mathias Burén
2012-05-08 9:59 ` Patelczyk, Maciej
2012-05-09 2:27 ` Shaohua Li
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