From: Christoph Hellwig <hch@infradead.org>
To: Sergey Meirovich <rathamahata@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>,
linux-scsi <linux-scsi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Gluk <git.user@gmail.com>
Subject: Re: Terrible performance of sequential O_DIRECT 4k writes in SAN environment. ~3 times slower then Solars 10 with the same HBA/Storage.
Date: Wed, 8 Jan 2014 07:26:10 -0800 [thread overview]
Message-ID: <20140108152610.GA5863@infradead.org> (raw)
In-Reply-To: <CA+QCeVQy08m9oBM1ULE_KAjd-36ao35p7-BCWErJewyr3m6NGg@mail.gmail.com>
On Wed, Jan 08, 2014 at 04:43:07PM +0200, Sergey Meirovich wrote:
> Results are almost the same:
> 14.68Mb/sec 3758.02 Requests/sec
>
On my laptop SSD I get the following results (sometimes up to 200MB/s,
sometimes down to 100MB/s, always in the 40k to 50k IOps range):
time elapsed (sec.): 5
bandwidth (MiB/s): 160.00
IOps: 40960.00
The IOps are more than the hardware is physically capable of, but given
that you didn't specify O_SYNC this seems sensible given that we never
have to flush the disk cache.
Could it be that your array has WCE=0? In Linux we'll never enable the
cache automatically, but Solaris does at least when using ZFS. Try
running:
sdparm --set=WCE /dev/sdX
and try again.
next prev parent reply other threads:[~2014-01-08 15:26 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-06 9:38 Terrible performance of sequential O_DIRECT 4k writes in SAN environment. ~3 times slower then Solars 10 with the same HBA/Storage Sergey Meirovich
2014-01-06 20:10 ` Jan Kara
2014-01-07 9:13 ` Sergey Meirovich
2014-01-07 15:58 ` Christoph Hellwig
2014-01-07 18:37 ` Sergey Meirovich
2014-01-08 14:03 ` Christoph Hellwig
2014-01-08 14:43 ` Sergey Meirovich
2014-01-08 15:26 ` Christoph Hellwig [this message]
2014-01-08 17:30 ` Sergey Meirovich
2014-01-08 20:55 ` Jan Kara
2014-01-09 10:11 ` Sergey Meirovich
2014-01-10 9:36 ` Jan Kara
2014-01-10 10:36 ` Sergey Meirovich
2014-01-10 10:48 ` Jan Kara
2014-01-10 14:32 ` Sergey Meirovich
2014-01-10 18:14 ` Sergey Meirovich
2014-01-14 13:30 ` Sergey Meirovich
2014-01-14 13:30 ` Sergey Meirovich
2014-01-15 22:07 ` Dave Chinner
2014-01-15 22:07 ` Dave Chinner
2014-01-20 13:58 ` Christoph Hellwig
2014-01-20 13:58 ` Christoph Hellwig
2014-01-20 22:18 ` Dave Chinner
2014-01-20 22:18 ` Dave Chinner
2014-01-08 1:17 ` Jan Kara
2014-01-08 14:03 ` Christoph Hellwig
2014-01-07 20:57 ` James Smart
2014-01-08 13:57 ` Sergey Meirovich
2014-01-09 19:54 ` Douglas Gilbert
2014-01-09 21:26 ` Sergey Meirovich
2014-01-09 21:43 ` Sergey Meirovich
-- strict thread matches above, loose matches on Subject: below --
2014-01-06 13:16 Sergey Meirovich
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