mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Arjan van de Ven <arjan@infradead.org>
To: knobi@knobisoft.de
Cc: Gleb Natapov <glebn@voltaire.com>, linux-kernel@vger.kernel.org
Subject: Re: How to detect multi-core and/or HT-enabled CPUs in 2.4.x and 2.6.x kernels
Date: Wed, 27 Dec 2006 17:09:32 +0100	[thread overview]
Message-ID: <1167235772.3281.3977.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <20061227155104.91856.qmail@web32607.mail.mud.yahoo.com>


> 
>  actually I wanted to write that "HT as implemented on XEONs did not
> help a lot for HPC workloads in the past"....


btw this is exactly the problem I am trying to point out: ".. as
implemented in generation XYZ model ABC of processor DEF".
that's going to be really fragile and in fact won't work even for
processors you can buy today (power5 and sparc niagara for example, and
depending on the workload, even on todays 16Mb cache Xeons).

once your program (and many others) have such a check, then the next
step will be pressure on the kernel code to "fake" the old situation
when there is a processor where <vague criteria of the day> no longer
holds. It's basically a road to madness :-(

-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org


  reply	other threads:[~2006-12-27 16:09 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-12-27 14:16 Martin Knoblauch
2006-12-27 14:24 ` Arjan van de Ven
2006-12-27 14:40   ` Martin Knoblauch
2006-12-27 15:13     ` Arjan van de Ven
2006-12-27 15:22       ` Gleb Natapov
2006-12-27 15:38         ` Arjan van de Ven
2006-12-27 15:41         ` Martin Knoblauch
2006-12-27 15:53           ` Arjan van de Ven
2006-12-27 15:51         ` Martin Knoblauch
2006-12-27 16:09           ` Arjan van de Ven [this message]
2006-12-27 17:14             ` Bernd Eckenfels
2006-12-27 17:52             ` Martin Knoblauch
2006-12-27 19:58               ` Siddha, Suresh B
2006-12-27 14:37 ` Jan Engelhardt

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=1167235772.3281.3977.camel@laptopd505.fenrus.org \
    --to=arjan@infradead.org \
    --cc=glebn@voltaire.com \
    --cc=knobi@knobisoft.de \
    --cc=linux-kernel@vger.kernel.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

all inboxes | Powered by JetHome®