From: Andi Kleen <ak@suse.de>
To: Lee Revell <rlrevell@joe-job.com>
Cc: Andi Kleen <ak@suse.de>, "Brown, Len" <len.brown@intel.com>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@osdl.org>,
acpi-devel@lists.sourceforge.net, nando@ccrma.Stanford.EDU,
linux-kernel@vger.kernel.org, paulmck@us.ibm.com, kr@cybsft.com,
tglx@linutronix.de, pluto@agmk.net, john.cooper@timesys.com,
bene@linutronix.de, dwalker@mvista.com,
trini@kernel.crashing.org, george@mvista.com
Subject: Re: [RFC][PATCH] Runtime switching of the idle function [take 2]
Date: Wed, 30 Nov 2005 02:06:46 +0100 [thread overview]
Message-ID: <20051130010646.GD19515@wotan.suse.de> (raw)
In-Reply-To: <1133308505.4627.31.camel@mindpipe>
> But on my system gettimeofday uses the TSC and it's still ~35x slower
> than RDTSC:
>
> rlrevell@mindpipe:~$ ./timetest
> rdtsc: 10000 calls in 1079 usecs
> gettimeofday: 10000 calls in 36628 usecs
First if you run this on an Athlon 64 the measurement is likely
wrong because RDTSC can be speculated around. To get accurate
data you need to add synchronizing instructions.
Then you're likely running 32bit. It doesn't use vsyscall gettimeofday
yet, which makes it slower. 64bit would.
-Andi
next prev parent reply other threads:[~2005-11-30 1:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-29 19:37 [RFC][PATCH] Runtime switching of the idle function [take 2] Brown, Len
2005-11-29 19:53 ` Andi Kleen
2005-11-29 20:35 ` Lee Revell
2005-11-29 20:51 ` Andi Kleen
2005-11-29 23:55 ` Lee Revell
2005-11-30 1:06 ` Andi Kleen [this message]
2005-11-30 1:22 ` Lee Revell
2005-11-30 1:58 ` Andi Kleen
2005-11-30 2:19 ` john stultz
[not found] <20051115090827.GA20411@elte.hu>
[not found] ` <1132336954.20672.11.camel@cmn3.stanford.edu>
[not found] ` <1132350882.6874.23.camel@mindpipe>
[not found] ` <1132351533.4735.37.camel@cmn3.stanford.edu>
[not found] ` <20051118220755.GA3029@elte.hu>
[not found] ` <1132353689.4735.43.camel@cmn3.stanford.edu>
[not found] ` <1132367947.5706.11.camel@localhost.localdomain>
[not found] ` <20051124150731.GD2717@elte.hu>
2005-11-25 20:56 ` [RFC][PATCH] Runtime switching to idle_poll (was: Re: 2.6.14-rt13) Steven Rostedt
2005-11-26 13:05 ` Ingo Molnar
2005-11-29 2:48 ` [RFC][PATCH] Runtime switching of the idle function [take 2] Steven Rostedt
2005-11-29 3:02 ` Andrew Morton
2005-11-29 3:42 ` Steven Rostedt
2005-11-29 4:01 ` Andrew Morton
2005-11-29 6:44 ` Ingo Molnar
2005-11-29 6:55 ` Nick Piggin
2005-11-29 18:05 ` Andi Kleen
2005-11-29 14:19 ` Steven Rostedt
2005-11-29 14:50 ` Andi Kleen
2005-11-29 15:42 ` Steven Rostedt
2005-12-02 1:27 ` Max Krasnyansky
2005-12-02 1:45 ` Andi Kleen
2005-12-03 2:17 ` Max Krasnyansky
2005-11-29 4:22 ` john stultz
2005-11-29 14:22 ` Steven Rostedt
2005-11-29 13:08 ` Pavel Machek
2005-12-18 15:26 ` Steven Rostedt
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