From: David Mosberger <davidm@napali.hpl.hp.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [PATCH] - sched_clock() broken for ia64 SN platform
Date: Thu, 20 Nov 2003 01:24:08 +0000 [thread overview]
Message-ID: <marc-linux-ia64-106929146824511@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-106928980122896@msgid-missing>
>>>>> On Wed, 19 Nov 2003 16:56:23 -0800 (PST), John Hawkes <hawkes@babylon.engr.sgi.com> said:
John> We might instead want to implement a more general scheme,
John> along the lines of what is done by (struct time_interpolator),
John> to provide a framework to solve this for other architectures
John> that have "drifty" non-default timebases.
My sense is that with a bit of thinking, it would be possible to come
up with a solution that allows even drifty platforms to use ITC for
sched_clock()---it serves very a specific purpose in the scheduler and
scalability is key and perfect accuracy is not (unlike for
gettimeofday). I don't think anything that goes out to read a single
(shared) platform counter will be sufficiently scalable to the number
of CPUs you guys are talking about. But yes, it would be much more
effort than just adding Yet Another Callback. The rewards would be
bigger, though, too...
--david
next prev parent reply other threads:[~2003-11-20 1:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-20 0:56 [PATCH] - sched_clock() broken for ia64 SN platform John Hawkes
2003-11-20 1:24 ` David Mosberger [this message]
2003-11-20 4:09 ` John Hawkes
2003-11-20 6:01 ` David Mosberger
2003-11-20 15:23 ` Jack Steiner
2003-11-20 17:25 ` Grant Grundler
2003-11-20 17:25 ` Rich Altmaier
2003-11-20 18:32 ` David Mosberger
2003-11-20 19:20 ` Robin Holt
2003-11-20 19:23 ` Robin Holt
2003-11-20 20:58 ` John Hawkes
2003-11-20 21:27 ` David Mosberger
2003-11-20 21:58 ` john stultz
2003-11-20 22:14 ` John Hawkes
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