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Message-ID: <d5ab9db3940ae708dcbe784bc2f85563ec9755df@intel.com>
Date: Thu, 03 Jul 2025 15:45:10 +0300
From: Jani Nikula <jani.nikula@...el.com>
To: Andi Shyti <andi.shyti@...nel.org>
Cc: linux-kernel@...r.kernel.org, intel-gfx@...ts.freedesktop.org, Thomas
Gleixner <tglx@...utronix.de>, Geert Uytterhoeven
<geert+renesas@...der.be>, Greg Kroah-Hartman
<gregkh@...uxfoundation.org>, ville.syrjala@...ux.intel.com
Subject: Re: [PATCH] iopoll: use fsleep() instead of usleep_range()
On Wed, 02 Jul 2025, Andi Shyti <andi.shyti@...nel.org> wrote:
> Hi Jani,
>
> On Thu, Jun 26, 2025 at 05:51:19PM +0300, Jani Nikula wrote:
>> Sometimes it's necessary to poll with long sleeps, and the accuracy of
>> usleep_range() is overkill. Use the flexible sleep helper fsleep() for
>> sleeping in the read_poll_timeout() family of macros to automatically
>> choose the appropriate method of waiting.
>>
>> Functionally there are a few consequences for existing users:
>>
>> - 10 us and shorter sleeps will use usleep() instead of
>> usleep_range(). Presumably this will not be an issue.
>>
>> - When it leads to a slack of less than 25%, msleep() will be used
>> instead of usleep_range(). Presumably this will not be an issue, given
>> the sleeps will be longer in this case.
>>
>> - Otherwise, the usleep_range() slack gets switched from the begin of
>> the range to the end of the range, i.e. [sleep/2+1..sleep] ->
>> [sleep..sleep+sleep/2]. In theory, this could be an issue in some
>> cases, but difficult to determine before this hits the real world.
>>
>> Signed-off-by: Jani Nikula <jani.nikula@...el.com>
>
> this patch makes sense to me even with the fixes in the commit
> message suggested byt Geert.
>
> Reviewed-by: Andi Shyti <andi.shyti@...nel.org>
Thanks! However I think Ville's series [1] should have more priority
here. It's mostly orthogonal, but IMO it's more important and should go
first. I can follow up with this one afterwards.
BR,
Jani.
[1] https://lore.kernel.org/r/20250702223439.19752-1-ville.syrjala@linux.intel.com
--
Jani Nikula, Intel
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