From: "Mathias Burén" <mathias.buren@gmail.com>
To: Shaohua Li <shli@kernel.org>
Cc: 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 02:29:21 +0000 [thread overview]
Message-ID: <CADNH=7EfmNRXq1bSyuUcRGy-8ksfNhJuGnopubTRomq8-oSmJw@mail.gmail.com> (raw)
In-Reply-To: <CANejiEUDmDzGirBZRwKh5MTHvXX308JTHmmH_U0JfnPJkpvHJQ@mail.gmail.com>
On 21 March 2012 02:08, Shaohua Li <shli@kernel.org> wrote:
> 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:
>>>
<snip>
> 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
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
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Many people prefer to have the filesystems mounted without discard,
then they run a TRIM command/script at night (or whenever the disk
isn't used very much). This way the TRIM commands don't slow down the
'overall' performance.
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
2012-03-21 2:29 ` Mathias Burén [this message]
2012-05-08 9:59 ` Patelczyk, Maciej
2012-05-09 2:27 ` Shaohua Li
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