From: Alex Dubov <oakad@yahoo.com>
To: akpm@linux-foundation.org,
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: maximlevitsky@gmail.com, fujita.tomonori@lab.ntt.co.jp,
James.Bottomley@HansenPartnership.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] scatterlist: new helper functions
Date: Tue, 15 Mar 2011 21:18:14 -0700 (PDT) [thread overview]
Message-ID: <403815.22502.qm@web37607.mail.mud.yahoo.com> (raw)
In-Reply-To: <20110316113527C.fujita.tomonori@lab.ntt.co.jp>
>
> I don't think so.
>
> Splitting (or merging) a request and playing with sg lists
> inside a
> driver is a bad idea. Such should be done in the block
> layer.
>
> I still don't see why the block layer can't do that for the
> driver.
>
> I believe that the helper functions for such should not be
> added.
>
In a particular case of flash-like devices, letting the block layer
split requests into memory sequential blocks too often results in
unnecessary fragmentation of writes/erases.
If only one sg entry is requested from the block layer, it will be (more
often than not) only 1 or 2 pages in length, even if total size of
prospective write request spans multiple erase blocks.
So there are really only two options for legacy memorystick driver:
1. Play with scatterlists explicitly.
2. Make it an MTD backend, rather then stand-alone block device.
The second option makes more sense, but it is not necessarily the optimal
approach for implementation of this particular media format.
next prev parent reply other threads:[~2011-03-16 4:25 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-04 4:16 [PATH 0/4] Memstick patches for 2.6.39 Maxim Levitsky
2011-03-04 4:16 ` [PATCH 1/4] scatterlist: new helper functions Maxim Levitsky
2011-03-06 7:29 ` FUJITA Tomonori
2011-03-06 15:14 ` Maxim Levitsky
2011-03-06 21:49 ` FUJITA Tomonori
2011-03-07 2:20 ` Maxim Levitsky
2011-03-09 17:24 ` Maxim Levitsky
2011-03-16 0:44 ` Andrew Morton
2011-03-16 2:35 ` FUJITA Tomonori
2011-03-16 4:18 ` Alex Dubov [this message]
2011-03-16 4:55 ` FUJITA Tomonori
2011-03-17 3:46 ` Alex Dubov
2011-03-17 3:57 ` James Bottomley
2011-03-16 22:33 ` Andrew Morton
2011-03-17 6:41 ` Alex Dubov
2011-03-17 13:17 ` Maxim Levitsky
2011-03-18 0:59 ` FUJITA Tomonori
2011-03-04 4:16 ` [PATCH 2/4] memstick: add support for legacy memorysticks Maxim Levitsky
2011-03-04 4:16 ` [PATCH 3/4] memstick: Add driver for Ricoh R5C592 card reader Maxim Levitsky
2011-03-16 4:25 ` Alex Dubov
2011-03-04 4:16 ` [PATCH 4/4] memstick: add Alex Dubov to MAINTAINERS of the memstick core Maxim Levitsky
2011-03-12 16:23 ` [PATH 0/4] Memstick patches for 2.6.39 Maxim Levitsky
2011-03-15 20:00 ` Maxim Levitsky
2011-03-15 21:04 ` Andrew Morton
2011-03-16 0:25 ` Maxim Levitsky
2011-03-20 3:09 ` Maxim Levitsky
2011-03-20 6:47 ` Andrew Morton
2011-03-20 11:42 ` Maxim Levitsky
2011-03-22 13:01 ` Maxim Levitsky
2011-03-22 23:21 ` Andrew Morton
2011-03-23 0:59 ` Maxim Levitsky
2011-03-23 3:42 ` Greg KH
2011-03-23 15:30 ` Maxim Levitsky
2011-03-24 3:27 ` Alex Dubov
-- strict thread matches above, loose matches on Subject: below --
2011-01-11 23:36 [PATCH V2 0/4]: MEMSTICK: My 2 drivers for 2.6.38 inclusion Maxim Levitsky
2011-01-11 23:36 ` [PATCH 1/4] scatterlist: new helper functions Maxim Levitsky
2011-01-11 23:51 ` Randy Dunlap
2011-01-11 23:55 ` Andrew Morton
2011-01-11 23:58 ` Randy Dunlap
2011-01-12 2:52 ` Maxim Levitsky
2011-01-12 6:41 ` Randy Dunlap
2011-01-11 2:58 Alex Dubov
2011-01-11 1:50 MEMSTICK: My 2 drivers for 2.6.38 inclusion Maxim Levitsky
2011-01-11 1:50 ` [PATCH 1/4] scatterlist: new helper functions Maxim Levitsky
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