From: Arnd Bergmann <arnd@arndb.de>
To: Chunhe Lan <b25806@freescale.com>
Cc: Chunhe Lan <Chunhe.Lan@freescale.com>,
linux-mmc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
kumar.gala@freescale.com, cjb@laptop.org,
Kumar Gala <galak@kernel.crashing.org>
Subject: Re: [PATCH v3 1/2] mmc: Move mmc_delay() to include/linux/mmc/core.h
Date: Fri, 21 Sep 2012 12:33:54 +0000 [thread overview]
Message-ID: <201209211233.54545.arnd@arndb.de> (raw)
In-Reply-To: <505CD3A5.6080101@freescale.com>
On Friday 21 September 2012, Chunhe Lan wrote:
> On 08/10/2012 09:27 AM, Arnd Bergmann wrote:
> > On Friday 10 August 2012, Chunhe Lan wrote:
> >
> > cond_resched();
> > mdelay(ms);
> >
> > sets off alarm bells, and I would always replace that with msleep().
> I think that it does not replace with msleep().
> When the time of sleep is very short, program should not been scheduled
> in the context. Because it expends the more time.
>
A time measured in miliseconds is never "very short" for the scheduler,
a lot of things can happen during that time span. The code I quoted
also does not care too much about accuracy, otherwise it would adapt
the time in the mdelay based on whether the cond_resched() actually
schedules to another thread.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Chunhe Lan <b25806@freescale.com>
Cc: kumar.gala@freescale.com, linux-mmc@vger.kernel.org,
cjb@laptop.org, linuxppc-dev@lists.ozlabs.org,
Chunhe Lan <Chunhe.Lan@freescale.com>
Subject: Re: [PATCH v3 1/2] mmc: Move mmc_delay() to include/linux/mmc/core.h
Date: Fri, 21 Sep 2012 12:33:54 +0000 [thread overview]
Message-ID: <201209211233.54545.arnd@arndb.de> (raw)
In-Reply-To: <505CD3A5.6080101@freescale.com>
On Friday 21 September 2012, Chunhe Lan wrote:
> On 08/10/2012 09:27 AM, Arnd Bergmann wrote:
> > On Friday 10 August 2012, Chunhe Lan wrote:
> >
> > cond_resched();
> > mdelay(ms);
> >
> > sets off alarm bells, and I would always replace that with msleep().
> I think that it does not replace with msleep().
> When the time of sleep is very short, program should not been scheduled
> in the context. Because it expends the more time.
>
A time measured in miliseconds is never "very short" for the scheduler,
a lot of things can happen during that time span. The code I quoted
also does not care too much about accuracy, otherwise it would adapt
the time in the mdelay based on whether the cond_resched() actually
schedules to another thread.
Arnd
next prev parent reply other threads:[~2012-09-21 12:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-10 22:25 [PATCH v3 1/2] mmc: Move mmc_delay() to include/linux/mmc/core.h Chunhe Lan
2012-08-10 22:25 ` Chunhe Lan
2012-08-10 13:27 ` Arnd Bergmann
2012-08-10 13:27 ` Arnd Bergmann
2012-09-21 20:52 ` Chunhe Lan
2012-09-21 20:52 ` Chunhe Lan
2012-09-21 12:33 ` Arnd Bergmann [this message]
2012-09-21 12:33 ` Arnd Bergmann
2012-09-24 15:20 ` Chunhe Lan
2012-09-24 15:20 ` Chunhe Lan
2012-09-24 13:17 ` Arnd Bergmann
2012-09-24 13:17 ` Arnd Bergmann
2012-09-24 14:38 ` Tabi Timur-B04825
2012-09-24 14:38 ` Tabi Timur-B04825
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