From: Linus Torvalds <torvalds@osdl.org>
To: Davide Libenzi <davidel@xmailserver.org>
Cc: Jamie Lokier <jamie@shareable.org>,
Nick Piggin <piggin@cyberone.com.au>,
bill davidsen <davidsen@tmr.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [CFT][RFC] HT scheduler
Date: Tue, 16 Dec 2003 16:41:35 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.58.0312161638230.1599@home.osdl.org> (raw)
In-Reply-To: <Pine.LNX.4.44.0312161609050.16848-100000@bigblue.dev.mdolabs.com>
On Tue, 16 Dec 2003, Davide Libenzi wrote:
> > I bet it is. In a big way.
> >
> > The lock does two independent things:
> > - it tells the core that it can't just crack up the load and store.
> > - it also tells other memory ops that they can't re-order around it.
>
> You forgot the one where no HT knowledge can be used for optimizations.
>
> - Asserting the CPU's #LOCK pin to take control of the system bus. That in
> MP system translate into the signaling CPU taking full control of the
> system bus until the pin is deasserted.
I think this is historical and no longer true.
All modern CPU's do atomic accesses on a cache coherency (and write buffer
ordering) level, and it has nothing to do with the external bus any more.
I suspect locked accesses to memory-mapped IO _may_ still set an external
flag, but I seriously doubt anybody cares. I wouldn't be surprised if the
pin doesn't even exist any more.
Linus
next prev parent reply other threads:[~2003-12-17 0:42 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-08 4:25 [PATCH][RFC] make cpu_sibling_map a cpumask_t Nick Piggin
2003-12-08 15:59 ` Anton Blanchard
2003-12-08 23:08 ` Nick Piggin
2003-12-09 0:14 ` Anton Blanchard
2003-12-11 4:25 ` [CFT][RFC] HT scheduler Nick Piggin
2003-12-11 7:24 ` Nick Piggin
2003-12-11 8:57 ` Nick Piggin
2003-12-11 11:52 ` William Lee Irwin III
2003-12-11 13:09 ` Nick Piggin
2003-12-11 13:23 ` William Lee Irwin III
2003-12-11 13:30 ` Nick Piggin
2003-12-11 13:32 ` William Lee Irwin III
2003-12-11 15:30 ` Nick Piggin
2003-12-11 15:38 ` William Lee Irwin III
2003-12-11 15:51 ` Nick Piggin
2003-12-11 15:56 ` William Lee Irwin III
2003-12-11 16:37 ` Nick Piggin
2003-12-11 16:40 ` William Lee Irwin III
2003-12-12 1:52 ` [PATCH] improve rwsem scalability (was Re: [CFT][RFC] HT scheduler) Nick Piggin
2003-12-12 2:02 ` Nick Piggin
2003-12-12 9:41 ` Ingo Molnar
2003-12-13 0:07 ` Nick Piggin
2003-12-14 0:44 ` Nick Piggin
2003-12-17 5:27 ` Nick Piggin
2003-12-19 11:52 ` Nick Piggin
2003-12-19 15:06 ` Martin J. Bligh
2003-12-20 0:08 ` Nick Piggin
2003-12-12 0:58 ` [CFT][RFC] HT scheduler Rusty Russell
2003-12-11 10:01 ` Rhino
2003-12-11 8:14 ` Nick Piggin
2003-12-11 16:49 ` Rhino
2003-12-11 15:16 ` Nick Piggin
2003-12-11 11:40 ` William Lee Irwin III
2003-12-11 17:05 ` Rhino
2003-12-11 15:17 ` William Lee Irwin III
2003-12-11 16:28 ` Kevin P. Fleming
2003-12-11 16:41 ` Nick Piggin
2003-12-12 2:24 ` Rusty Russell
2003-12-12 7:00 ` Nick Piggin
2003-12-12 7:23 ` Rusty Russell
2003-12-13 6:43 ` Nick Piggin
2003-12-14 1:35 ` bill davidsen
2003-12-14 2:18 ` Nick Piggin
2003-12-14 4:32 ` Jamie Lokier
2003-12-14 9:40 ` Nick Piggin
2003-12-14 10:46 ` Arjan van de Ven
2003-12-16 17:46 ` Bill Davidsen
2003-12-16 18:22 ` Linus Torvalds
2003-12-17 0:24 ` Davide Libenzi
2003-12-17 0:41 ` Linus Torvalds [this message]
2003-12-17 0:54 ` Davide Libenzi
2003-12-16 17:34 ` Bill Davidsen
2003-12-15 5:53 ` Rusty Russell
2003-12-15 23:08 ` Nick Piggin
2003-12-19 4:57 ` Nick Piggin
2003-12-19 5:13 ` Nick Piggin
2003-12-20 2:43 ` Rusty Russell
2003-12-21 2:56 ` Nick Piggin
2004-01-03 18:57 ` Bill Davidsen
2003-12-15 20:21 ` Zwane Mwaikambo
2003-12-15 23:20 ` Nick Piggin
2003-12-16 0:11 ` Zwane Mwaikambo
2003-12-12 8:59 ` Nick Piggin
2003-12-12 15:14 ` Martin J. Bligh
2003-12-08 19:44 ` [PATCH][RFC] make cpu_sibling_map a cpumask_t James Cleverdon
2003-12-08 20:38 ` Ingo Molnar
2003-12-08 20:51 ` Zwane Mwaikambo
2003-12-08 20:55 ` Ingo Molnar
2003-12-08 23:17 ` Nick Piggin
2003-12-08 23:36 ` Ingo Molnar
2003-12-08 23:58 ` Nick Piggin
2003-12-08 23:46 ` Rusty Russell
2003-12-09 13:36 ` Nick Piggin
2003-12-11 21:41 ` bill davidsen
[not found] <20031213022038.300B22C2C1@lists.samba.org.suse.lists.linux.kernel>
[not found] ` <3FDAB517.4000309@cyberone.com.au.suse.lists.linux.kernel>
[not found] ` <brgeo7$huv$1@gatekeeper.tmr.com.suse.lists.linux.kernel>
[not found] ` <3FDBC876.3020603@cyberone.com.au.suse.lists.linux.kernel>
[not found] ` <20031214043245.GC21241@mail.shareable.org.suse.lists.linux.kernel>
[not found] ` <3FDC3023.9030708@cyberone.com.au.suse.lists.linux.kernel>
[not found] ` <1071398761.5233.1.camel@laptop.fenrus.com.suse.lists.linux.kernel>
2003-12-14 16:26 ` [CFT][RFC] HT scheduler Andi Kleen
2003-12-14 16:54 ` Arjan van de Ven
[not found] <200312161127.13691.habanero@us.ibm.com>
2003-12-16 17:37 ` Andrew Theurer
2003-12-17 2:41 ` Nick Piggin
2003-12-16 19:03 Nakajima, Jun
2003-12-17 0:38 Nakajima, Jun
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=Pine.LNX.4.58.0312161638230.1599@home.osdl.org \
--to=torvalds@osdl.org \
--cc=davidel@xmailserver.org \
--cc=davidsen@tmr.com \
--cc=jamie@shareable.org \
--cc=linux-kernel@vger.kernel.org \
--cc=piggin@cyberone.com.au \
/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).