From: Will Newton <will.newton@gmail.com>
To: Timur Tabi <timur@freescale.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org, rdreier@cisco.com,
jirislaby@gmail.com, peterz@infradead.org, hancockrwd@gmail.com,
jeremy@goop.org
Subject: Re: [PATCH v4] introduce macro spin_event_timeout()
Date: Tue, 10 Mar 2009 16:05:20 +0000 [thread overview]
Message-ID: <87a5b0800903100905l71f15141n7a273df21bfa77e2@mail.gmail.com> (raw)
In-Reply-To: <49B68C37.8010803@freescale.com>
On Tue, Mar 10, 2009 at 3:50 PM, Timur Tabi <timur@freescale.com> wrote:
> Alan Cox wrote:
>
>> NAK this - on a lot of platforms 1uS is the wrong timescale. Also we
>> shouldn't be encouraging this kind of polling by making it very easy to
>> write.
>
> Well, I can agree that the time scale might be wrong on some platforms.
> The original version of spin_event_timeout() used jiffies, but some
> people said that a jiffy is too long of a timescale, so I changed it to
> udelay.
The correct timescale is rather application dependant - for some
accesses that cross clock domains it can be a requirement to wait for
a small number of core clock cycles (2 - 20) for a condition to become
true, for others, e.g. PIO, it is more appropriate to wait for a few
100 cycles.
next prev parent reply other threads:[~2009-03-10 16:06 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-10 15:30 Timur Tabi
2009-03-10 15:35 ` Alan Cox
2009-03-10 15:50 ` Timur Tabi
2009-03-10 16:05 ` Will Newton [this message]
2009-03-10 16:11 ` Timur Tabi
2009-03-11 0:01 ` Benjamin Herrenschmidt
2009-03-11 0:37 ` Alan Cox
2009-03-11 16:48 ` Timur Tabi
2009-03-11 16:58 ` Alan Cox
2009-03-11 18:18 ` Timur Tabi
2009-03-11 21:58 ` Benjamin Herrenschmidt
2009-03-12 2:45 ` Grant Likely
2009-03-12 15:54 ` Timur Tabi
2009-03-12 16:01 ` Grant Likely
2009-03-12 16:19 ` Timur Tabi
2009-03-12 16:50 ` Peter Zijlstra
2009-03-12 19:05 ` Timur Tabi
2009-03-13 3:03 ` Benjamin Herrenschmidt
2009-03-13 4:51 ` Grant Likely
2009-03-10 18:41 ` Grant Likely
2009-03-10 19:04 ` Timur Tabi
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