From: Timur Tabi <timur@freescale.com>
To: Jiri Slaby <jirislaby@gmail.com>
Cc: linux-kernel@vger.kernel.org, rdreier@cisco.com,
peterz@infradead.org, will.newton@gmail.com
Subject: Re: [PATCH v3] add function spin_event_timeout()
Date: Mon, 09 Mar 2009 15:54:19 -0500 [thread overview]
Message-ID: <49B581FB.7060506@freescale.com> (raw)
In-Reply-To: <49B57F45.7040104@gmail.com>
Jiri Slaby wrote:
> On 9.3.2009 21:32, Timur Tabi wrote:
>> +#define spin_event_timeout(condition, timeout) \
>> +({ \
>> + int __timeout = timeout; \
>> + while (!(condition)&& --__timeout) { \
>> + udelay(1); \
>> + cpu_relax(); \
>
> So you don't need cpu_relax anymore...
I checked the udelay() code. It varies per platform, but I didn't see
how it always replicated the functionality of cpu_relax(). For example,
in x86_64, cpu_relax is a "rep; nop;". But I don't see that code
sequence in arch/x86/lib/delay.c.
So I presume that something in the delay functions makes cpu_relax()
unnecessary. What exactly is the purpose of cpu_relax()?
> And I would make timeout UL like delay functions.
I made it an integer because I don't expect anyone to pass a value
larger than 2^31, but I'll change it.
--
Timur Tabi
Linux kernel developer at Freescale
next prev parent reply other threads:[~2009-03-09 20:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-09 20:32 [PATCH v3] add function spin_event_timeout() Timur Tabi
2009-03-09 20:42 ` Jiri Slaby
2009-03-09 20:54 ` Timur Tabi [this message]
2009-03-10 0:37 ` Robert Hancock
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