From: Jonas Oreland <jonas@mysql.com>
To: Ray Bryant <raybry@mpdtxmail.amd.com>
Cc: Andi Kleen <ak@suse.de>, Daniel Jacobowitz <dan@debian.org>,
john stultz <johnstul@us.ibm.com>, Andrew Morton <akpm@osdl.org>,
lkml <linux-kernel@vger.kernel.org>,
discuss@x86-64.org
Subject: Re: [discuss] Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs
Date: Thu, 22 Sep 2005 10:00:47 +0200 [thread overview]
Message-ID: <433264AF.5060800@mysql.com> (raw)
In-Reply-To: <200509211046.25555.raybry@mpdtxmail.amd.com>
Ray Bryant wrote:
> On Wednesday 21 September 2005 10:04, Andi Kleen wrote:
>
>
>>We handle this, but single socket dual core was special cased because
>>I was told previously it should be ok.
>>
>>-Andi
>
>
> AFAIK there is a processor state bit that enables/disables this behavior.
> Apparently some BIOS's are setting this one way for desktop systems and the
> other way for servers. If it is thought to be important I can track that
> down and see if it can be externally documented. (It may actually be in the
> bios and kernel developer guide...)
>
Hi,
This would be very good (for us single socket dual core users)
I tried a very small benchmark:
clock_gettime(CLOCK_REALTIME): elapsed 7336657 -> 733.665700ns/call
clock_gettime(CLOCK_PROCESS_CPUTIME_ID): elapsed 763247 -> 76.324700ns/call
It's a factor 10 faster if the TSC were to be in sync.
/Jonas
next prev parent reply other threads:[~2005-09-22 7:57 UTC|newest]
Thread overview: 28+ 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 [this message]
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
2005-10-26 0:05 ` David Lang
-- strict thread matches above, loose matches on Subject: below --
2005-09-20 19:13 [discuss] Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs Langsdorf, Mark
2005-09-20 19:24 ` Scott Lampert
2005-09-20 19:30 ` john stultz
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=433264AF.5060800@mysql.com \
--to=jonas@mysql.com \
--cc=ak@suse.de \
--cc=akpm@osdl.org \
--cc=dan@debian.org \
--cc=discuss@x86-64.org \
--cc=johnstul@us.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=raybry@mpdtxmail.amd.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox