From: Tom Rini <trini@konsulko.com>
To: u-boot@lists.denx.de
Subject: [PATCH] powerpc: reduce number of WATCHDOG_RESET calls from flush_cache
Date: Thu, 24 Sep 2020 08:32:16 -0400 [thread overview]
Message-ID: <20200924123216.GD14816@bill-the-cat> (raw)
In-Reply-To: <3933429.1600865298@gemini.denx.de>
On Wed, Sep 23, 2020 at 02:48:18PM +0200, Wolfgang Denk wrote:
> Dear Rasmus,
>
> In message <afea5640-9d95-bf92-316a-0d674a5129ce@prevas.dk> you wrote:
> > On 04/06/2020 12.31, Stefan Roese wrote:
> > > On 04.06.20 11:30, Rasmus Villemoes wrote:
> > >> Calling WATCHDOG_RESET for each and every cache line is overkill.
> > >>
> > >> In our case, the kernel image is a little over 7MB, and the almost
> > >> 500000 calls of WATCHDOG_RESET() adds about one second to the
> > >> boottime.
> > >>
> > >> I very highly doubt there's any real hardware where flushing 64K
> > >> from cache to memory takes more than a few milliseconds, so this
> > >> should be completely safe. Since it reduces the number of
>
> Maybe it is, maybe it is not. I remember boards where the watchdog
> trigger had to happen in pretty tight intervals, something like min
> 20, max 60 milliseconds.
>
> > >> +??????? if ((addr & (SZ_64K - 1)) == 0)
>
> In any case, please write readable code. The use of SZ_ here is not
> a good idea. Also, you might want to make the actual parameter
> configurable, so boards with specific timing requirements can adjust
> this as needed.
We should add a comment somewhere here to match the commit message, but
since we're flushing on 64K chunks, SZ_64K makes sense. If we make it
build-time configurable then it's not a concern. I assume we don't want
to make this run time configurable.
--
Tom
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next prev parent reply other threads:[~2020-09-24 12:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-04 9:30 [PATCH] powerpc: reduce number of WATCHDOG_RESET calls from flush_cache Rasmus Villemoes
2020-06-04 10:31 ` Stefan Roese
2020-09-18 8:20 ` Rasmus Villemoes
2020-09-18 14:50 ` Tom Rini
2020-09-23 12:48 ` Wolfgang Denk
2020-09-24 12:32 ` Tom Rini [this message]
2020-09-23 13:28 ` Priyanka Jain
2020-09-24 10:57 ` Wolfgang Denk
2020-09-24 12:32 ` Tom Rini
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