From: Ravi Shankar <ravi.v.shankar@oracle.com>
To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: "Abhilash Sankar - ERS, HCL Tech" <Abhilash.S@hcl.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"linux-iscsi-target-dev@googlegroups.com"
<linux-iscsi-target-dev@googlegroups.com>, "Yuvarani C - ERS ,
HCLTech" <yuvaranic@hcl.com>,
"Bagavathy Kumar Mahendran - ERS,
HCL Tech" <bagavathykumar.m@hcl.com>,
target-devel <target-devel@vger.kernel.org>
Subject: Re: LIO performance Issue
Date: Thu, 15 Sep 2011 12:47:26 -0700 [thread overview]
Message-ID: <4E72564E.8000406@oracle.com> (raw)
In-Reply-To: <1316031025.12820.95.camel@haakon2.linux-iscsi.org>
>>
>
> Hi Abhilash,
>
> By default target_core_file.c is using O_SYNC to ensure that WRITEs are
> written directly to disk before acknowledging back to the SCSI client.
> This will have a considerable effect on FILEIO WRITE performance, but is
> done by default to ensure proper data integrity in the face of target
> power loss.
>
> You may want to double check the filp_open() flags with SCST to ensure
> that you are comparing 'apples to apples' here. Optionally you can try
> disabling O_SYNC with target_core_file.c via rtslib with the class
> FileIOStorageObject:_set_buffered_mode() mentioned here:
>
>
Another area to consider improvement is how SCSI Target Data phase are
handled.
The target framework should split SCSI data phases into multiple smaller
IO to increase
performance. In other work instead of synchronous data phase it need to
be asynchronous.
--ravi
next prev parent reply other threads:[~2011-09-15 19:47 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-14 14:00 LIO performance Issue Abhilash Sankar - ERS, HCL Tech
2011-09-14 20:10 ` Nicholas A. Bellinger
2011-09-15 19:47 ` Ravi Shankar [this message]
2011-09-16 13:51 ` Christoph Hellwig
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