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Subject: Re: [RFC] slight UBI scan time improvement
From: Artem Bityutskiy <dedekind@infradead.org>
To: Hamish Moffatt <hamish@cloud.net.au>
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Date: Wed, 23 Apr 2008 15:57:47 +0300
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On Wed, 2008-04-23 at 22:40 +1000, Hamish Moffatt wrote:
> Well I think from past use of "time ubiattach ..." that most of
> the missing time is in the attach.=20
Sure, UBI takes most of the time. Its just if you want to save 1.2+ sec,
you may try to play with on-flash BBT.

> Would combining the bad block scan with the UBI scan save time? I guess
> it would be a bad layering violation however :-)
Yeah, it could be done as custom hack but not for mainstream.

> What sort of speed do you get using
> dd if=3D/dev/mtdblock9 of=3D/tmp/foo bs=3D128K count=3D64
> (where mtdblock9 is your raw mtd NAND device). I'm seeing about 6
> seconds to read that 8Mb, which is quite long I guess.

I have busybox so stuff like 128K does not work. Here are my results:

# time dd if=3D/dev/mtd4 of=3D/dev/null bs=3D131072 count=3D64
64+0 records in
64+0 records out
real    0m 0.28s
user    0m 0.00s
sys     0m 0.28s

# time dd if=3D/dev/mtd4 of=3D/dev/null bs=3D131072 count=3D256
256+0 records in
256+0 records out
real    0m 1.12s
user    0m 0.00s
sys     0m 1.11s

Its OneNAND which has a controller and it is quite quick.

--=20
Best regards,
Artem Bityutskiy (=D0=91=D0=B8=D1=82=D1=8E=D1=86=D0=BA=D0=B8=D0=B9 =D0=90=
=D1=80=D1=82=D1=91=D0=BC)