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From: Andi Kleen <ak@suse.de>
To: Suleiman Souhlal <ssouhlal@freebsd.org>
Cc: Linux Kernel ML <linux-kernel@vger.kernel.org>,
	vojtech@suse.cz, Jiri Bohac <jbohac@suse.cz>
Subject: Re: [PATCH 0/2] Make the TSC safe to be used by gettimeofday().
Date: Tue, 14 Nov 2006 02:50:57 +0100	[thread overview]
Message-ID: <200611140250.57160.ak@suse.de> (raw)
In-Reply-To: <455916A5.2030402@FreeBSD.org>

On Tuesday 14 November 2006 02:06, Suleiman Souhlal wrote:
> I've had a proof-of-concept for this since August, and finally got around to
> somewhat cleaning it up.

Thanks. 

I got a competing implementation for this unfortunately now from Vojtech & Jiri

Yours is simpler, but I'm not sure as complete. What are your assurances
against non monoticity for example?

> 
> It can certainly still be improved, namely by using vgetcpu() instead of CPUID
> to find the cpu number (but I couldn't get it to work, when I tried).

What did not work?

> Another possible improvement would be to use RDTSCP when available.
> There's also a small race in do_gettimeofday(), vgettimeofday() and
> vmonotonic_clock() but I've never seen it happen.

I did a vposix_getclock with monotonic clock support on my own already, was about to 
be merged with the vDSO. It still used global synchronized TSC though.

-Andi 

  parent reply	other threads:[~2006-11-14  1:51 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-11-14  1:06 [PATCH 0/2] Make the TSC safe to be used by gettimeofday() Suleiman Souhlal
2006-11-14  1:08 ` [PATCH 1/2] " Suleiman Souhlal
2006-11-14  2:05   ` Andi Kleen
2006-11-14  2:25     ` Suleiman Souhlal
2006-11-14  2:44       ` Andi Kleen
2006-11-14  3:35         ` dean gaudet
2006-11-14  4:22           ` dean gaudet
2006-11-14  3:54         ` Suleiman Souhlal
2006-11-14 11:12           ` Andi Kleen
2006-11-14  1:09 ` [PATCH 2/2] Introduce a vmonotonic_clock() vsyscall Suleiman Souhlal
2006-11-14  1:50 ` Andi Kleen [this message]
2006-11-14  2:06   ` [PATCH 0/2] Make the TSC safe to be used by gettimeofday() Suleiman Souhlal
2006-11-14 11:10     ` [PATCH 0/2] Make the TSC safe to be used by gettimeofday() II Andi Kleen
2006-11-14 12:30     ` [PATCH 0/2] Make the TSC safe to be used by gettimeofday() Shem Multinymous
2006-11-14 17:06       ` Suleiman Souhlal
2006-11-14 18:30         ` Andi Kleen
2006-11-14 21:28     ` Christoph Lameter
2006-11-14  7:42   ` Arjan van de Ven

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