From: Nick Piggin <piggin@cyberone.com.au>
To: Linus Torvalds <torvalds@osdl.org>
Cc: john stultz <johnstul@us.ibm.com>,
Joel Becker <Joel.Becker@oracle.com>,
lkml <linux-kernel@vger.kernel.org>,
Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Subject: Re: get_cycles() on i386
Date: Wed, 05 Nov 2003 14:02:49 +1100 [thread overview]
Message-ID: <3FA86859.8040306@cyberone.com.au> (raw)
In-Reply-To: <3FA86645.7030302@cyberone.com.au>
Nick Piggin wrote:
>
>
> Linus Torvalds wrote:
>
>> On 4 Nov 2003, john stultz wrote:
>>
>>> CONFIG_X86_TSC be the devil. Personally, I'd much prefer dropping the
>>> compile time option and using dynamic detection. Something like (not
>>> recently tested and i believe against 2.5.something, but you get the
>>> idea):
>>>
>>
>> Some of the users are really timing-critical (eg scheduler).
>>
>
> The scheduler uses its own sched_clock which only gives jiffies
> resolution if CONFIG_NUMA is defined. Unfortunate because I think
> its interactive behaviour isn't so good with ms resolution.
>
> The scheduler does not need to have synchronised TSCs though, I think.
> It just means 2 more calls to sched_clock in a slow path (smp migration).
>
Well no, its much trickier than that I think :(
next prev parent reply other threads:[~2003-11-05 3:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-04 23:22 get_cycles() on i386 Joel Becker
2003-11-04 23:27 ` john stultz
2003-11-04 23:54 ` Linus Torvalds
2003-11-05 2:53 ` Nick Piggin
2003-11-05 3:02 ` Nick Piggin [this message]
2003-11-05 13:35 ` Marcelo Tosatti
2003-12-05 15:55 ` Marcelo Tosatti
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=3FA86859.8040306@cyberone.com.au \
--to=piggin@cyberone.com.au \
--cc=Joel.Becker@oracle.com \
--cc=johnstul@us.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=marcelo.tosatti@cyclades.com \
--cc=torvalds@osdl.org \
/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;
as well as URLs for NNTP newsgroup(s).