From: Gautham R Shenoy <ego@in.ibm.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
Rusty Russel <rusty@rustcorp.com.au>,
Srivatsa Vaddagiri <vatsa@in.ibm.com>,
Dipankar Sarma <dipankar@in.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Nathan Lynch <ntl@pobox.com>
Subject: [RFC PATCH 5/5] Update get_online_cpus() in Documentation/cpu-hotplug.c
Date: Wed, 24 Oct 2007 11:09:07 +0530 [thread overview]
Message-ID: <20071024053907.GE27074@in.ibm.com> (raw)
In-Reply-To: <20071024052931.GA22722@in.ibm.com>
Update the documentation for cpu hotplug to reflect the use
of newly added API's get_online_cpus()/put_online_cpus();
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
---
Documentation/cpu-hotplug.txt | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
Index: linux-2.6.23/Documentation/cpu-hotplug.txt
===================================================================
--- linux-2.6.23.orig/Documentation/cpu-hotplug.txt
+++ linux-2.6.23/Documentation/cpu-hotplug.txt
@@ -109,12 +109,13 @@ Never use anything other than cpumask_t
for_each_cpu_mask(x,mask) - Iterate over some random collection of cpu mask.
#include <linux/cpu.h>
- lock_cpu_hotplug() and unlock_cpu_hotplug():
+ get_online_cpus() and put_online_cpus():
-The above calls are used to inhibit cpu hotplug operations. While holding the
-cpucontrol mutex, cpu_online_map will not change. If you merely need to avoid
-cpus going away, you could also use preempt_disable() and preempt_enable()
-for those sections. Just remember the critical section cannot call any
+The above calls are used to inhibit cpu hotplug operations. While the
+cpu_hotplug.refcount is non zero, the cpu_online_map will not change.
+If you merely need to avoid cpus going away, you could also use
+preempt_disable() and preempt_enable() for those sections.
+Just remember the critical section cannot call any
function that can sleep or schedule this process away. The preempt_disable()
will work as long as stop_machine_run() is used to take a cpu down.
--
Gautham R Shenoy
Linux Technology Center
IBM India.
"Freedom comes with a price tag of responsibility, which is still a bargain,
because Freedom is priceless!"
next prev parent reply other threads:[~2007-10-24 5:39 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 ` Gautham R Shenoy [this message]
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
2007-10-24 18:22 ` Gautham R Shenoy
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