From: Pavel Machek <pavel@suse.cz>
To: Vojtech Pavlik <vojtech@suse.cz>
Cc: Andi Kleen <ak@muc.de>, Dmitry Torokhov <dtor@insightbb.com>,
Rusty Russell <rusty@rustcorp.com.au>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Turn rdmsr, rdtsc into inline functions, clarify names
Date: Mon, 14 Aug 2006 20:13:00 +0000 [thread overview]
Message-ID: <20060814201300.GA4032@ucw.cz> (raw)
In-Reply-To: <20060807124855.GB21003@suse.cz>
Hi!
> > > > > Would not preempt_disable fix that?
> > > >
> > > > Partially, but you still have other problems. Please just get rid
> > > > of it. Why do we have timer code in the kernel if you then chose
> > > > not to use it?
> > >
> > > The problem is that gettimeofday() is not always fast.
> >
> > When it is not fast that means it is not reliable and then you're
> > also not well off using it anyways.
>
> I assume you wanted to say "When gettimeofday() is slow, it means TSC is
> not reliable", which I agree with.
>
> But I need, in the driver, in the no-TSC case use i/o counting, not a
> slow but reliable method. And I can't say, from outside the timing
> subsystem, whether gettimeofday() is fast or slow.
do gettimeofday(); gettimeofday(); gettimeofday();, then compare the
result with gettimeofday(); inb(); gettimeofday(); ?
Pavel
--
Thanks for all the (sleeping) penguins.
next prev parent reply other threads:[~2006-08-15 18:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1154771262.28257.38.camel@localhost.localdomain>
2006-08-06 2:38 ` [PATCH] Turn rdmsr, rdtsc into inline functions, clarify names Andi Kleen
2006-08-06 2:56 ` Rusty Russell
2006-08-06 2:58 ` H. Peter Anvin
2006-08-06 3:09 ` Rusty Russell
2006-08-06 3:11 ` H. Peter Anvin
2006-08-06 3:49 ` Rusty Russell
2006-08-06 3:16 ` Andi Kleen
2006-08-06 3:52 ` Rusty Russell
2006-08-06 14:58 ` Andi Kleen
2006-08-07 2:43 ` Dmitry Torokhov
2006-08-07 8:48 ` Andi Kleen
2006-08-07 11:09 ` Vojtech Pavlik
2006-08-07 12:28 ` Andi Kleen
2006-08-07 12:48 ` Vojtech Pavlik
2006-08-07 12:56 ` Andi Kleen
2006-08-07 13:18 ` Vojtech Pavlik
2006-08-07 13:32 ` Dmitry Torokhov
2006-08-07 15:01 ` Andi Kleen
2006-08-07 15:19 ` Andreas Mohr
2006-08-07 15:57 ` Andi Kleen
2006-08-07 16:04 ` Vojtech Pavlik
2006-08-07 16:12 ` Andi Kleen
2006-08-07 19:22 ` Vojtech Pavlik
2006-08-14 20:13 ` Pavel Machek [this message]
2006-08-07 11:07 ` Vojtech Pavlik
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