From: John Reiser <jreiser@BitWagon.com>
To: Andi Kleen <ak@suse.de>
Cc: Stephane Eranian <eranian@hpl.hp.com>,
Ray Bryant <raybry@mpdtxmail.amd.com>,
discuss@x86-64.org, linux-kernel@vger.kernel.org,
perfctr-devel@lists.sourceforge.net
Subject: Re: [Perfctr-devel] Re: Enabling RDPMC in user space by default
Date: Tue, 29 Nov 2005 10:29:47 -0800 [thread overview]
Message-ID: <438C9E1B.8040204@BitWagon.com> (raw)
In-Reply-To: <20051129181344.GN19515@wotan.suse.de>
Andi Kleen wrote:
> I think it's also a useful convention - RDTSC is becomming more and more
> useless and you cannot expect user applications who just want to
> measure some cycles to rely on ever changing instable or non existing
> performance counter APIs.
Users are even more unhappy with ever-changing ABIs -- such as the
kernel taking away RDTSC.
RDTSC+perfctr [Pettersson] still is the fastest way for user-mode code
to count something that is highly correlated with both "billable"
CPU time and "code quality" for a fixed task. With a little care
RDTSC is close enough to monotonic that I find it very useful.
Please don't take away user-mode RDTSC.
--
next prev parent reply other threads:[~2005-11-29 18:32 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-29 15:15 Enabling RDPMC in user space by default Andi Kleen
2005-11-29 16:04 ` Mikael Pettersson
2005-11-29 16:17 ` Andi Kleen
2005-11-29 16:56 ` Ray Bryant
2005-11-29 16:15 ` Andi Kleen
2005-11-29 18:09 ` [Perfctr-devel] " Stephane Eranian
2005-11-29 18:13 ` Andi Kleen
2005-11-29 18:29 ` John Reiser [this message]
2005-11-29 18:38 ` Andi Kleen
2005-11-29 19:05 ` Lee Revell
2005-11-29 21:43 ` Nicholas Miell
2005-11-29 21:52 ` Andi Kleen
2005-11-29 22:19 ` Stephane Eranian
2005-11-29 22:51 ` [discuss] " Andi Kleen
2005-11-30 16:01 ` Stephane Eranian
2005-11-30 16:23 ` Andi Kleen
2005-12-01 23:41 ` Stephane Eranian
2005-12-02 0:07 ` Andi Kleen
2005-12-02 7:09 ` Stephane Eranian
2005-12-02 11:36 ` Andi Kleen
2005-11-29 22:33 ` Nicholas Miell
2005-11-29 22:43 ` Andi Kleen
2005-11-29 23:02 ` Nicholas Miell
2005-11-29 23:17 ` Andi Kleen
2005-11-29 23:29 ` Nicholas Miell
2005-11-29 23:39 ` Andi Kleen
2005-11-29 23:56 ` David Gibson
2005-11-30 0:34 ` Andi Kleen
2005-11-30 0:52 ` David Gibson
2005-11-30 1:04 ` [discuss] " Andi Kleen
2005-11-30 0:50 ` Ray Bryant
2005-11-30 0:38 ` Andi Kleen
2005-11-30 7:38 ` Stephane Eranian
2005-11-30 8:22 ` Nicholas Miell
2005-11-30 15:48 ` Stephane Eranian
2005-11-29 23:07 ` David Gibson
2005-11-29 23:18 ` [discuss] " Andi Kleen
2005-11-29 23:28 ` Bernd Schmidt
2005-11-29 23:46 ` [discuss] " Andi Kleen
2005-11-30 2:39 ` Zwane Mwaikambo
2005-11-30 3:38 ` Andi Kleen
2005-12-01 4:08 ` Zwane Mwaikambo
2005-12-01 13:05 ` Andi Kleen
2005-12-01 17:01 ` Zwane Mwaikambo
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