linux-kernel - Re: [PATCHv3 4/5] mtd: mxc

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Date:	Fri, 25 Jun 2010 16:46:44 +0200
From:	Ivo Clarysse <ivo.clarysse@...il.com>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	linux-arm-kernel@...ts.infradead.org,
	John Ogness <john.ogness@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 4/5] mtd: mxc_nand fixups

On Thu, Jun 24, 2010 at 9:27 AM, Sascha Hauer <s.hauer@...gutronix.de> wrote:
[...]
>
> BTW I observed that at least on i.MX27 the latencies introduced by
> waiting for an interrupt cause a significant performance drop. The
> driver gets much faster when we just poll all the time. I don't know how
> this affects system performance otherwise, but it may be a possibility
> to drop interrupt support at least for i.MX21. I have no idea how long
> the longest possible time we'd have to poll is though.

I'm noticing the same thing on i.MX21: when using interrupts,
"Scanning device for bad blocks" takes 982 (!) seconds.  When always
using polling, the same scan takes 'only' 500 seconds.


Ivo.
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