From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Zwane Mwaikambo <zwane@linuxpower.ca>
Cc: Andrew Morton <akpm@osdl.org>,
torvalds@osdl.org, paulus@samba.org,
linux-kernel@vger.kernel.org, anton@samba.org,
jun.nakajima@intel.com, ak@suse.de, mingo@elte.hu
Subject: Re: [PATCH] Yielding processor resources during lock contention
Date: Sun, 12 Sep 2004 14:32:47 +1000 [thread overview]
Message-ID: <4143D16F.30500@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.53.0409120108310.2297@montezuma.fsmlabs.com>
Zwane Mwaikambo wrote:
> On Sat, 11 Sep 2004, Andrew Morton wrote:
>>Now, maybe Paul has tied himself into sufficiently tangly locking knots
>>that in some circumstances he needs to spin on the lock and cannot schedule
>>away. But he can still use a semaphore and spin on down_trylock.
>>
>>Confused by all of this.
>
>
> Well currently it just enables preempt and spins like a mad man until the
> lock is free. The idea is to allow preempt to get some scheduling done
> during the spin.. But! if you accept this patch today, you get the
> i386 version which will allow your processor to halt until a write to the
> lock occurs whilst allowing interrupts to also trigger the preempt
> scheduling, much easier on the caches.
>
That's the idea though isn't it? If your locks are significantly more
expensive than a context switch and associated cache trashing, use a
semaphore, hypervisor or no.
I presume the hypervisor switch much incur the same sorts of costs as
a context switch?
next prev parent reply other threads:[~2004-09-12 5:27 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-03 0:02 [PATCH][5/8] Arch agnostic completely out of line locks / ppc64 Zwane Mwaikambo
2004-09-09 5:42 ` Paul Mackerras
2004-09-09 12:41 ` Zwane Mwaikambo
2004-09-09 14:54 ` Linus Torvalds
2004-09-09 14:55 ` Linus Torvalds
2004-09-09 15:32 ` Zwane Mwaikambo
2004-09-12 4:59 ` [PATCH] Yielding processor resources during lock contention Zwane Mwaikambo
2004-09-12 5:00 ` Andrew Morton
2004-09-12 5:10 ` Anton Blanchard
2004-09-12 5:13 ` Zwane Mwaikambo
2004-09-12 4:32 ` Nick Piggin [this message]
2004-09-12 5:33 ` Zwane Mwaikambo
2004-09-12 4:46 ` Nick Piggin
2004-09-12 5:51 ` Zwane Mwaikambo
2004-09-12 5:02 ` Nick Piggin
2004-09-12 6:09 ` Anton Blanchard
2004-09-12 6:58 ` William Lee Irwin III
2004-09-12 5:18 ` Andrew Morton
2004-09-12 5:10 ` Linus Torvalds
2004-09-12 5:27 ` Zwane Mwaikambo
2004-09-13 12:21 ` [PATCH] Yielding processor resources during lock contention #2 Zwane Mwaikambo
2004-09-12 7:49 ` [PATCH] Yielding processor resources during lock contention Ingo Molnar
2004-09-12 16:10 ` Zwane Mwaikambo
2004-09-12 19:34 ` Ingo Molnar
2004-09-12 10:10 ` Arnd Bergmann
2004-09-12 10:43 ` Anton Blanchard
2004-09-12 11:12 ` Arnd Bergmann
2004-09-09 15:43 ` [PATCH][5/8] Arch agnostic completely out of line locks / ppc64 Anton Blanchard
2004-09-09 17:19 ` William Lee Irwin III
2004-09-09 21:38 ` Paul Mackerras
2004-09-09 22:00 ` William Lee Irwin III
2004-09-09 23:36 ` Paul Mackerras
2004-09-10 0:09 ` William Lee Irwin III
2004-09-10 0:21 ` Linus Torvalds
2004-09-10 0:35 ` Anton Blanchard
2004-09-10 0:54 ` Linus Torvalds
2004-09-10 1:42 ` Anton Blanchard
2004-09-10 1:50 ` Anton Blanchard
2004-09-10 2:22 ` William Lee Irwin III
2004-09-10 2:32 ` William Lee Irwin III
2004-09-10 2:37 ` William Lee Irwin III
2004-09-10 3:24 ` Anton Blanchard
2004-09-10 7:40 ` Ingo Molnar
2004-09-10 12:16 ` William Lee Irwin III
2004-09-10 12:22 ` Ingo Molnar
2004-09-10 3:23 ` Anton Blanchard
2004-09-10 7:56 ` Anton Blanchard
-- strict thread matches above, loose matches on Subject: below --
2004-09-13 0:45 [PATCH] Yielding processor resources during lock contention Nakajima, Jun
2004-09-13 1:35 Nakajima, Jun
2004-09-13 6:35 ` Ingo Molnar
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=4143D16F.30500@yahoo.com.au \
--to=nickpiggin@yahoo.com.au \
--cc=ak@suse.de \
--cc=akpm@osdl.org \
--cc=anton@samba.org \
--cc=jun.nakajima@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=paulus@samba.org \
--cc=torvalds@osdl.org \
--cc=zwane@linuxpower.ca \
/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