From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: "Ted Ts'o" <tytso@mit.edu>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Eric Sandeen <sandeen@redhat.com>,
linux-ext4@vger.kernel.org, Lukas Czerner <lczerner@redhat.com>
Subject: Re: Some interesting input from a flash manufacturer
Date: Wed, 07 Mar 2012 23:36:39 -0500 [thread overview]
Message-ID: <yq1r4x3hfoo.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <20120307005203.GB5717@thunk.org> (Ted Ts'o's message of "Tue, 6 Mar 2012 19:52:03 -0500")
>>>>> "Ted" == Ted Ts'o <tytso@mit.edu> writes:
Ted> But min_io currently means the smallest size that we're allowed to
Ted> write, correct?
Without incurring a penalty, yes. That was conceived in the standards
with 4K sectors and RAID RMW in mind. But I think it would apply to SSDs
as well. Depending on how mkfs.* interpret the field, obviously.
Ted> And the flash page size could be 128k and 512 byte writes might be
Ted> perfectly OK; it's just that writes are more optimal at 128k, and
Ted> would be even more optimal at the erbase block size of 4 megs.
Yep. Just like in the RAID case where the writing the full stripe chunk
is better than just a logical block. And a full stripe is even better.
Ted> That's why I'm not sure it makes sense to use the existing fields,
Ted> since it will confuse file system utilities that are reading those
Ted> fields.
Happy to add new fields if it makes sense. But right now ATA ACS doesn't
even have anything corresponding to the SCSI fields that populate min_io
and opt_io.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2012-03-08 4:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-02 21:00 Some interesting input from a flash manufacturer Theodore Ts'o
2012-03-02 21:04 ` Eric Sandeen
2012-03-02 23:11 ` Ted Ts'o
2012-03-06 1:12 ` Greg Freemyer
2012-03-06 18:44 ` Martin K. Petersen
2012-03-07 0:52 ` Ted Ts'o
2012-03-08 4:36 ` Martin K. Petersen [this message]
2012-03-06 18:42 ` Martin K. Petersen
2012-03-05 7:00 ` Lukas Czerner
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