From: Andi Kleen <ak@suse.de>
To: Jiri Bohac <jbohac@suse.cz>
Cc: linux-kernel@vger.kernel.org, Vojtech Pavlik <vojtech@suse.cz>,
ssouhlal@freebsd.org, arjan@infradead.org, tglx@linutronix.de,
johnstul@us.ibm.com, zippel@linux-m68k.org, andrea@suse.de,
Recent@suse.de, Addresses@suse.de
Subject: Re: [patch 9/9] Make use of the Master Timer
Date: Fri, 2 Feb 2007 08:04:29 +0100 [thread overview]
Message-ID: <200702020804.29824.ak@suse.de> (raw)
In-Reply-To: <20070201142927.GR21755@dwarf.suse.cz>
On Thursday 01 February 2007 15:29, Jiri Bohac wrote:
> If I do:
> rdtscll(a)
> ...
> rdtscll(b)
> is it guaranteed that (b > a) ?
It's not architecturally -- unless you have a barrier.
On P4 the micro architecture guarantees it, but there the barrier in
get_cycles_sync is patched away. On other x86-64s it is generally needed.
The effect can be also seen between CPUs.
> Because of the __vxtime.cpu[cpu].tsc_invalid flag. We may be
You can still precompute it for the HPET etc. case.
They are already slow, but saving a condition there might be still
worth it.
-Andi
next prev parent reply other threads:[~2007-02-02 7:22 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-01 9:59 [patch 0/9] x86_64: reliable TSC-based gettimeofday jbohac
2007-02-01 9:59 ` [patch 1/9] Fix HPET init race jbohac
2007-02-02 2:34 ` Andrew Morton
2007-02-06 16:44 ` Jiri Bohac
2007-02-07 0:12 ` Andrew Morton
2007-02-10 12:31 ` Andi Kleen
2007-07-26 20:58 ` Robin Holt
2007-02-01 9:59 ` [patch 2/9] Remove the support for the VXTIME_PMTMR timer mode jbohac
2007-02-01 11:13 ` Andi Kleen
2007-02-01 13:13 ` Jiri Bohac
2007-02-01 13:13 ` Andi Kleen
2007-02-01 13:59 ` Jiri Bohac
2007-02-01 14:18 ` Andi Kleen
2007-02-01 9:59 ` [patch 3/9] Remove the support for the VXTIME_HPET " jbohac
2007-02-01 9:59 ` [patch 4/9] Remove the TSC synchronization on SMP machines jbohac
2007-02-01 11:14 ` Andi Kleen
2007-02-01 13:17 ` Jiri Bohac
2007-02-01 15:16 ` Vojtech Pavlik
2007-02-02 7:14 ` Andi Kleen
2007-02-13 0:34 ` Christoph Lameter
2007-02-13 6:40 ` Arjan van de Ven
2007-02-13 8:28 ` Andi Kleen
2007-02-13 8:41 ` Arjan van de Ven
2007-02-13 17:09 ` Christoph Lameter
2007-02-13 17:20 ` Andi Kleen
2007-02-13 22:18 ` Vojtech Pavlik
2007-02-13 22:38 ` Andrea Arcangeli
2007-02-14 6:59 ` Vojtech Pavlik
2007-02-13 23:55 ` Christoph Lameter
2007-02-14 0:18 ` Paul Mackerras
2007-02-14 0:25 ` john stultz
2007-02-02 7:13 ` Andi Kleen
2007-02-01 21:05 ` mbligh
2007-02-03 1:16 ` H. Peter Anvin
2007-02-01 9:59 ` [patch 5/9] Add all the necessary structures to the vsyscall page jbohac
2007-02-01 11:17 ` Andi Kleen
2007-02-01 9:59 ` [patch 6/9] Add the "Master Timer" jbohac
2007-02-01 11:22 ` Andi Kleen
2007-02-01 13:29 ` Jiri Bohac
2007-02-01 9:59 ` [patch 7/9] Adapt the time initialization code jbohac
2007-02-01 11:26 ` Andi Kleen
2007-02-01 13:41 ` Jiri Bohac
2007-02-01 10:00 ` [patch 8/9] Add time_update_mt_guess() jbohac
2007-02-01 11:28 ` Andi Kleen
2007-02-01 13:54 ` Jiri Bohac
2007-02-01 10:00 ` [patch 9/9] Make use of the Master Timer jbohac
2007-02-01 11:36 ` Andi Kleen
2007-02-01 14:29 ` Jiri Bohac
2007-02-01 15:23 ` Vojtech Pavlik
2007-02-02 7:05 ` Andi Kleen
2007-02-02 7:04 ` Andi Kleen [this message]
2007-02-01 11:20 ` [patch 0/9] x86_64: reliable TSC-based gettimeofday Andi Kleen
2007-02-01 11:53 ` Andrea Arcangeli
2007-02-01 12:02 ` Andi Kleen
2007-02-01 12:54 ` Andrea Arcangeli
2007-02-01 12:17 ` Ingo Molnar
2007-02-01 14:52 ` Jiri Bohac
2007-02-01 16:56 ` john stultz
2007-02-01 19:41 ` Vojtech Pavlik
2007-02-01 11:34 ` Ingo Molnar
2007-02-01 11:46 ` [-mm patch] x86_64 GTOD: offer scalable vgettimeofday Ingo Molnar
2007-02-01 12:01 ` Andi Kleen
2007-02-01 12:14 ` Ingo Molnar
2007-02-01 12:17 ` [-mm patch] x86_64 GTOD: offer scalable vgettimeofday II Andi Kleen
2007-02-01 12:24 ` Ingo Molnar
2007-02-01 12:45 ` Andi Kleen
2007-02-02 4:22 ` [patch 0/9] x86_64: reliable TSC-based gettimeofday Andrew Morton
2007-02-02 7:07 ` Andi Kleen
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