From: Benjamin LaHaise <bcrl@kvack.org>
To: Zachary Amsden <zach@vmware.com>
Cc: Chuck Ebbert <76306.1226@compuserve.com>,
Linus Torvalds <torvalds@osdl.org>, Andi Kleen <ak@suse.de>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [rfc patch] i386: don't save eflags on task switch
Date: Sat, 4 Nov 2006 22:55:56 -0500 [thread overview]
Message-ID: <20061105035556.GQ9057@kvack.org> (raw)
In-Reply-To: <454CE576.3000709@vmware.com>
On Sat, Nov 04, 2006 at 11:09:42AM -0800, Zachary Amsden wrote:
> Every processor I've ever measured it on, popf is slower. On P4, for
> example, pushf is 6 cycles, and popf is 54. On Opteron, it is 2 / 12.
> On Xeon, it is 7 / 91.
pushf has to wait until all flag dependancies can be resolved. On the
P4 with >100 instructions in flight, that can take a long time. Popf
on the other hand has no dependancies on outstanding instructions as it
resets the machine state.
-ben
--
"Time is of no importance, Mr. President, only life is important."
Don't Email: <dont@kvack.org>.
next prev parent reply other threads:[~2006-11-05 3:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-04 6:56 [rfc patch] i386: don't save eflags on task switch Chuck Ebbert
2006-11-04 19:09 ` Zachary Amsden
2006-11-04 19:35 ` Linus Torvalds
2006-11-05 3:55 ` Benjamin LaHaise [this message]
2006-11-05 4:13 ` Linus Torvalds
2006-11-05 5:41 ` Andi Kleen
2006-11-05 8:01 ` Zachary Amsden
2006-11-05 17:01 ` Andi Kleen
2006-11-05 17:26 ` Linus Torvalds
2006-11-05 17:34 ` Arjan van de Ven
2006-11-05 17:51 ` Linus Torvalds
2006-11-05 22:48 ` Zachary Amsden
2006-11-05 18:52 ` Andi Kleen
2006-11-05 16:12 ` Linus Torvalds
2006-11-05 16:54 ` Andi Kleen
2006-11-05 17:20 ` Linus Torvalds
2006-11-05 4:17 ` Zachary Amsden
2006-11-05 20:10 ` H. Peter Anvin
-- strict thread matches above, loose matches on Subject: below --
2006-11-04 0:00 Chuck Ebbert
2006-11-04 0:46 ` Linus Torvalds
2006-11-04 1:36 ` Andi Kleen
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=20061105035556.GQ9057@kvack.org \
--to=bcrl@kvack.org \
--cc=76306.1226@compuserve.com \
--cc=ak@suse.de \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@osdl.org \
--cc=zach@vmware.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