From: Jonathan Corbet <corbet@lwn.net>
To: Israel Schlesinger <israels@codeaurora.org>
Cc: linux-kernel@vger.kernel.org, apw@canonical.com,
akpm@linux-foundation.org, joe@perches.com
Subject: Re: [PATCH] checkpatch: Add warnings for use of mdelay()
Date: Tue, 27 Jul 2010 11:31:33 -0600 [thread overview]
Message-ID: <20100727113133.1605c9fe@bike.lwn.net> (raw)
In-Reply-To: <4C4F132F.6020401@codeaurora.org>
On Tue, 27 Jul 2010 10:11:11 -0700
Israel Schlesinger <israels@codeaurora.org> wrote:
> mdelay is a busy-wait loop which is wasteful. If at all possible,
> callers should use msleep instead of mdelay.
>
> The only time mdelay is really appropriate is in atomic context,
> however, delays of 1ms+ in atomic context are rather expensive, so
> a warning for this case is probably appropriate as well to encourage
> people to move such expensive delays outside of atomic context
Once upon a time, msleep(1) would sleep for 20ms, while mdelay(1) gave
a 1ms delay. My patch to fix msleep() at that time didn't get in due
to concerns about the cost of using hrtimers. Perhaps msleep() has
gotten better, but, if not, actually getting a 1ms delay remains a
valid reason for using mdelay() instead IMO. It made a difference of a
few seconds at open time for a driver I was doing at the time.
jon
next prev parent reply other threads:[~2010-07-27 17:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-27 17:11 [PATCH] checkpatch: Add warnings for use of mdelay() Israel Schlesinger
2010-07-27 17:22 ` Joe Perches
2010-07-27 17:31 ` Jonathan Corbet [this message]
2010-07-27 17:32 ` Patrick Pannuto
2010-07-27 19:16 ` Andrew Morton
2010-07-28 9:44 ` Andy Whitcroft
2018-07-04 18:18 Prakruthi Deepak Heragu
2018-07-04 18:30 ` Joe Perches
2018-07-05 8:19 ` Dan Carpenter
2018-07-06 5:49 ` Julia Lawall
2018-07-07 12:09 ` Jia-Ju Bai
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