Re: [PATCH] UBI: Decrease I/O count in ubi_scan

Artem Bityutskiy
2009-07-21T12:14:47Z

On Tue, 2009-07-21 at 13:26 +0200, Corentin Chary wrote:
> Merge ec_hdr and vid_hdr read in one ubi_io_read()
> This result in a 25% speedup with nandsim, and 6%
> speedup on an AT91SAM9263 board with a 200Mo UBI volume.
>
> Signed-off-by: Corentin Chary <corentincj@iksaif.net>
> ---
> drivers/mtd/ubi/io.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++-
> drivers/mtd/ubi/scan.c | 35 +++++++++++++------------
> drivers/mtd/ubi/ubi.h | 4 +++
> 3 files changed, 87 insertions(+), 19 deletions(-)

Yeah, I did the same optimization some time ago:

http://lists.infradead.org/pipermail/linux-mtd/2008-April/021311.html

Could you please take a look at those patches as well, and if they
are any better, use them or improve yours. I do not remember the
details, to be frank.

No one reported a significant improvement, so I dropped it.
nandsim improvement is not very interesting, but the AT91SAM9263 is.
Which flash is there? And why do you presume is the improvement -
just less calls to MTD or really less I/O? Note MTD usually caches
the last read NAND page, so usually this is not about less I/O.

--
Best Regards,
Artem Bityutskiy (Артём Битюцкий)