From: Andi Kleen <ak@suse.de>
To: Jonas Oreland <jonas@mysql.com>
Cc: john stultz <johnstul@us.ibm.com>,
lkml <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>,
discuss@x86-64.org
Subject: Re: x86-64: Syncing dualcore cpus TSCs
Date: Tue, 25 Oct 2005 09:42:25 +0200 [thread overview]
Message-ID: <200510250942.25973.ak@suse.de> (raw)
In-Reply-To: <435DE042.9060208@mysql.com>
On Tuesday 25 October 2005 09:35, Jonas Oreland wrote:
> Hi,
>
> This might be a very bad suggestion, but here it is:
>
> On dualcore cpus (amd64) the TSC will get out of sync when executing hlt
> instruction. booting with idle=poll, will make it never to execute hlt,
> hence TSC will be in sync. booting with notsc will make it use other time
> source...but this is slower (this is default after "[PATCH] x86-64: Fix bad
> assumption that dualcore cpus have synced TSCs")
>
> How about syncing TSC after hlt?
>
> If cost of syncing TSC's is smaller than cost of using other time source
> this might be an alternative.
I very doubt it is. Syncing TSCs requires stopping multiple CPUs for longer
time. It is unlikely you can make that up.
-Andi
next prev parent reply other threads:[~2005-10-25 7:41 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-19 19:16 [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs john stultz
2005-09-19 19:31 ` Andi Kleen
2005-09-19 19:42 ` john stultz
2005-09-19 19:49 ` [discuss] " Andi Kleen
2005-09-20 18:59 ` john stultz
2005-09-21 4:03 ` Daniel Jacobowitz
2005-09-21 15:15 ` Ray Bryant
2005-09-21 15:04 ` Andi Kleen
2005-09-21 15:46 ` Ray Bryant
2005-09-22 8:00 ` Jonas Oreland
2005-09-21 20:17 ` Andrew Morton
2005-10-07 12:26 ` Vladimir B. Savkin
2005-10-07 12:31 ` Andi Kleen
2005-10-07 14:15 ` Vladimir B. Savkin
2005-10-07 14:21 ` [discuss] " Velu Erwan
2005-10-08 10:11 ` Vladimir B. Savkin
2005-10-10 18:03 ` john stultz
2005-10-10 18:12 ` Vladimir B. Savkin
2005-10-10 18:19 ` Jonas Oreland
2005-10-11 7:35 ` Vladimir B. Savkin
2005-10-11 8:06 ` Andi Kleen
2005-10-11 16:27 ` Jonas Oreland
2005-10-25 7:35 ` x86-64: Syncing dualcore cpus TSCs Jonas Oreland
2005-10-25 7:42 ` Andi Kleen [this message]
2005-10-26 0:05 ` David Lang
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