From: Andi Kleen <andi@firstfloor.org>
To: Daniel Walker <dwalker@mvista.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Bill Huey <billh@gnuppy.monkey.org>,
Jason Baron <jbaron@redhat.com>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 3/5] lockstat: core infrastructure
Date: 01 Jun 2007 16:25:47 +0200 [thread overview]
Message-ID: <p73sl9bbvkk.fsf@bingen.suse.de> (raw)
In-Reply-To: <1180545913.32594.194.camel@imap.mvista.com>
Daniel Walker <dwalker@mvista.com> writes:
> On Wed, 2007-05-30 at 19:16 +0200, Peter Zijlstra wrote:
>
> > > >From the architecture perspective there are two low level clock hooks to
> > > implement one is sched_clock() , and at least one clocksource structure.
> > > Both do essentially the same thing. With timekeepings clocksource
> > > structure actually being easier to implement cause the math is built in.
> >
> > I think you are mistaken here; the two are similar but not identical.
> >
> > I see sched_clock() as fast first, accurate second. Whereas the
> > clocksource thing is accurate first, fast second.
>
> This is true .. However, if there is a speed different it's small.
pmtimer (factor 1000+) or HPET (factor 10-100+ depending on CPU)
accesses are much slower than TSC or jiffies read. Talking to the
southbridge is slow.
-Andi
next prev parent reply other threads:[~2007-06-01 13:29 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-29 12:52 [PATCH 0/5] lock contention tracking -v3 Peter Zijlstra
2007-05-29 12:52 ` [PATCH 1/5] fix raw_spinlock_t vs lockdep Peter Zijlstra
2007-05-29 12:52 ` [PATCH 2/5] lockdep: sanitise CONFIG_PROVE_LOCKING Peter Zijlstra
2007-05-29 13:21 ` Christoph Hellwig
2007-05-29 14:16 ` Ingo Molnar
2007-05-30 3:14 ` Andrew Morton
2007-05-29 12:52 ` [PATCH 3/5] lockstat: core infrastructure Peter Zijlstra
2007-05-29 20:28 ` Daniel Walker
2007-05-30 13:03 ` Peter Zijlstra
2007-05-30 13:24 ` Ingo Molnar
2007-05-30 13:40 ` Steven Rostedt
2007-05-30 13:49 ` Ingo Molnar
2007-05-30 17:06 ` Daniel Walker
2007-05-30 17:16 ` Peter Zijlstra
2007-05-30 17:25 ` Daniel Walker
2007-06-01 13:12 ` Ingo Molnar
2007-06-01 15:26 ` Daniel Walker
2007-06-01 15:52 ` Peter Zijlstra
2007-06-01 16:11 ` Daniel Walker
2007-06-01 18:30 ` Ingo Molnar
2007-06-01 19:25 ` Matt Mackall
2007-06-01 19:30 ` Daniel Walker
2007-06-01 18:43 ` Peter Zijlstra
2007-06-01 18:51 ` Ingo Molnar
2007-06-01 19:30 ` Daniel Walker
2007-06-01 18:19 ` Ingo Molnar
2007-06-01 19:30 ` Daniel Walker
2007-06-01 14:25 ` Andi Kleen [this message]
2007-05-30 15:20 ` Daniel Walker
2007-05-30 3:43 ` Andrew Morton
2007-05-29 12:52 ` [PATCH 4/5] lockstat: human readability tweaks Peter Zijlstra
2007-05-29 12:52 ` [PATCH 5/5] lockstat: hook into spinlock_t, rwlock_t, rwsem and mutex Peter Zijlstra
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