From: Wolfram Sang <w.sang@pengutronix.de>
To: Andrei Warkentin <andreiw@motorola.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-mmc@vger.kernel.org
Subject: Re: MMC quirks relating to performance/lifetime.
Date: Tue, 8 Feb 2011 22:38:25 +0100 [thread overview]
Message-ID: <20110208213825.GB29410@pengutronix.de> (raw)
In-Reply-To: <AANLkTikh4vfS7SLKAa-aUXhbTxcHzYHmBuaXj1qHHYN9@mail.gmail.com>
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On Tue, Feb 08, 2011 at 03:22:59PM -0600, Andrei Warkentin wrote:
> Hi,
>
> I'm not sure if this is the best place to bring this up, but Russel's
> name is on a fair share of drivers/mmc code, and there does seem to be
> quite a bit of MMC-related discussions. Excuse me in advance if this
> isn't the right forum :-).
Searching for MMC in MAINTAINERS will get you:
MULTIMEDIA CARD (MMC), SECURE DIGITAL (SD) AND SDIO SUBSYSTEM
M: Chris Ball <cjb@laptop.org>
L: linux-mmc@vger.kernel.org
...
List CCed...
> Certain MMC vendors (maybe even quite a bit of them) use a pretty
> rigid buffering scheme when it comes to handling writes. There is
> usually a buffer A for random accesses, and a buffer B for sequential
> accesses. For certain Toshiba parts, it looks like buffer A is 8KB
> wide, with buffer B being 4MB wide, and all accesses larger than 8KB
> effectively equating to 4MB accesses. Worse, consecutive small (8k)
> writes are treated as one large sequential access, once again ending
> up in buffer B, thus necessitating out-of-order writing to work around
> this.
>
> What this means is decreased life span for the parts, and it also
> means a performance impact on small writes, but the first item is much
> more crucial, especially for smaller parts.
>
> As I've mentioned, probably more vendors are affected. How about a
> generic MMC_BLOCK quirk that splits the requests (and optionally
> reorders) them? The thresholds would then be adjustable as
> module/kernel parameters based on manfid. I'm asking because I have a
> patch now, but its ugly and hardcoded against a specific manufacturer.
>
> Thanks,
> A
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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next parent reply other threads:[~2011-02-08 21:38 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AANLkTikh4vfS7SLKAa-aUXhbTxcHzYHmBuaXj1qHHYN9@mail.gmail.com>
2011-02-08 21:38 ` Wolfram Sang [this message]
2011-02-09 8:37 ` MMC quirks relating to performance/lifetime Linus Walleij
2011-02-09 9:13 ` Arnd Bergmann
2011-02-11 22:33 ` Andrei Warkentin
2011-02-12 17:05 ` Arnd Bergmann
2011-02-12 17:33 ` Andrei Warkentin
2011-02-12 18:22 ` Arnd Bergmann
2011-02-18 1:10 ` Andrei Warkentin
2011-02-18 13:44 ` Arnd Bergmann
2011-02-18 19:47 ` Andrei Warkentin
2011-02-18 22:40 ` Andrei Warkentin
2011-02-18 23:17 ` Andrei Warkentin
2011-02-19 11:20 ` Arnd Bergmann
2011-02-20 5:56 ` Andrei Warkentin
2011-02-20 15:23 ` Arnd Bergmann
2011-02-22 7:05 ` Andrei Warkentin
2011-02-22 16:49 ` Arnd Bergmann
2011-02-19 9:54 ` Arnd Bergmann
2011-02-20 4:39 ` Andrei Warkentin
2011-02-20 15:03 ` Arnd Bergmann
2011-02-22 6:42 ` Andrei Warkentin
2011-02-22 16:42 ` Arnd Bergmann
2011-02-11 23:23 ` Linus Walleij
2011-02-12 10:45 ` Arnd Bergmann
2011-02-12 10:59 ` Russell King - ARM Linux
2011-02-12 16:28 ` Arnd Bergmann
2011-02-12 16:37 ` Russell King - ARM Linux
2011-02-11 22:27 ` Andrei Warkentin
2011-02-12 18:37 ` Arnd Bergmann
2011-02-13 0:10 ` Andrei Warkentin
2011-02-13 17:39 ` Arnd Bergmann
2011-02-14 19:29 ` Andrei Warkentin
2011-02-14 20:22 ` Arnd Bergmann
2011-02-14 22:25 ` Andrei Warkentin
2011-02-15 17:16 ` Arnd Bergmann
2011-02-17 2:08 ` Andrei Warkentin
2011-02-17 15:47 ` Arnd Bergmann
2011-02-20 11:27 ` Andrei Warkentin
2011-02-20 14:39 ` Arnd Bergmann
2011-02-22 7:46 ` Andrei Warkentin
2011-02-22 17:00 ` Arnd Bergmann
2011-02-23 10:19 ` Andrei Warkentin
2011-02-23 16:09 ` Arnd Bergmann
2011-02-23 22:26 ` Andrei Warkentin
2011-02-24 9:24 ` Arnd Bergmann
2011-02-25 11:02 ` Andrei Warkentin
2011-02-25 12:21 ` Arnd Bergmann
2011-03-01 18:48 ` Jens Axboe
2011-03-01 19:11 ` Arnd Bergmann
2011-03-01 19:15 ` Jens Axboe
2011-03-01 19:51 ` Arnd Bergmann
2011-03-01 21:33 ` Andrei Warkentin
2011-03-02 10:34 ` Andrei Warkentin
2011-03-05 9:23 ` Andrei Warkentin
[not found] ` <201102111551.15508.arnd@arndb.de>
[not found] ` <20110308065911.GC1357@ucw.cz>
2011-03-08 14:03 ` Arnd Bergmann
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