From: Oleg Nesterov <oleg@tv-sign.ru>
To: Gautham R Shenoy <ego@in.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Rusty Russel <rusty@rustcorp.com.au>,
Srivatsa Vaddagiri <vatsa@in.ibm.com>,
Dipankar Sarma <dipankar@in.ibm.com>, Ingo Molnar <mingo@elte.hu>,
Paul E McKenney <paulmck@us.ibm.com>,
Richard Gooch <rgooch@atnf.csiro.au>,
Tigran Aivazian <tigran@aivazian.fs.co.uk>,
Shoahua Li <shaohua.li@linux.com>,
Ralf Baechle <ralf@linux-mips.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Nathan Lynch <ntl@pobox.com>, David Miller <davem@davemloft.net>,
Paul Jackson <pj@sgi.com>, Josh Triplett <josh@freedesktop.org>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Akinobu Mita <akinobu.mita@gmail.com>
Subject: Re: [RFC PATCH 0/5] Refcount based Cpu Hotplug. V2
Date: Wed, 24 Oct 2007 22:17:54 +0400 [thread overview]
Message-ID: <20071024181754.GC345@tv-sign.ru> (raw)
In-Reply-To: <20071024180034.GB8663@in.ibm.com>
On 10/24, Gautham R Shenoy wrote:
>
> On Wed, Oct 24, 2007 at 10:04:41AM -0700, Christoph Lameter wrote:
> > On Wed, 24 Oct 2007, Gautham R Shenoy wrote:
> >
> > > This is the version 2 of the refcount based cpu-hotplug "locking"
> > > implementation.
> >
> > Uggh. This introduces a global lock that has to be taken always when
> > scanning over cpus?
>
> Well, no! we take the global lock only while bumping up the refcount.
> We don't hold the lock while scanning over the cpus. And this is
> definitely an improvement over the lock_cpu_hotplug() global mutex
> we have now.
Just to be sure I didn't miss something... preempt_disable() still works,
yes?
Oleg.
next prev parent reply other threads:[~2007-10-24 18:13 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-24 5:29 [RFC PATCH 0/5] Refcount based Cpu Hotplug. V2 Gautham R Shenoy
2007-10-24 5:30 ` [RFC PATCH 1/5] Refcount Based Cpu Hotplug implementation Gautham R Shenoy
2007-10-24 5:32 ` [RFC PATCH 2/5] Replace lock_cpu_hotplug() with get_online_cpus() Gautham R Shenoy
2007-10-24 5:34 ` [RFC PATCH 3/5] Replace per-subsystem mutexes " Gautham R Shenoy
2007-10-24 5:37 ` [RFC PATCH 4/5] Remove CPU_DEAD/CPU_UP_CANCELLED handling from workqueue.c Gautham R Shenoy
2007-10-24 7:21 ` Rusty Russell
2007-10-24 8:35 ` Gautham R Shenoy
2007-10-24 13:44 ` Oleg Nesterov
2007-10-24 13:38 ` Oleg Nesterov
2007-10-24 17:45 ` Gautham R Shenoy
2007-10-24 18:14 ` Oleg Nesterov
2007-10-24 5:39 ` [RFC PATCH 5/5] Update get_online_cpus() in Documentation/cpu-hotplug.c Gautham R Shenoy
2007-10-24 17:04 ` [RFC PATCH 0/5] Refcount based Cpu Hotplug. V2 Christoph Lameter
2007-10-24 18:00 ` Gautham R Shenoy
2007-10-24 18:17 ` Oleg Nesterov [this message]
2007-10-24 18:22 ` Gautham R Shenoy
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