From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: linux-doc@vger.kernel.org, peterz@infradead.org,
fweisbec@gmail.com, linux-kernel@vger.kernel.org,
walken@google.com, mingo@kernel.org, linux-arch@vger.kernel.org,
vincent.guittot@linaro.org, xiaoguangrong@linux.vnet.ibm.com,
wangyun@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com,
nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org,
Rusty Russell <rusty@rustcorp.com.au>,
rostedt@goodmis.org, rjw@sisk.pl, namhyung@kernel.org,
tglx@linutronix.de, linux-arm-kernel@lists.infradead.org,
netdev@vger.kernel.org, oleg@redhat.com, sbw@mit.edu,
tj@kernel.org, akpm@linux-foundation.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v5 00/45] CPU hotplug: stop_machine()-free CPU hotplug
Date: Fri, 08 Feb 2013 23:39:54 +0530 [thread overview]
Message-ID: <51153F72.1060005@linux.vnet.ibm.com> (raw)
In-Reply-To: <51152B81.2050501@linux.vnet.ibm.com>
On 02/08/2013 10:14 PM, Srivatsa S. Bhat wrote:
> On 02/08/2013 09:11 PM, Russell King - ARM Linux wrote:
>> On Thu, Feb 07, 2013 at 11:41:34AM +0530, Srivatsa S. Bhat wrote:
>>> On 02/07/2013 09:44 AM, Rusty Russell wrote:
>>>> "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> writes:
>>>>> On 01/22/2013 01:03 PM, Srivatsa S. Bhat wrote:
>>>>> Avg. latency of 1 CPU offline (ms) [stop-cpu/stop-m/c latency]
>>>>>
>>>>> # online CPUs Mainline (with stop-m/c) This patchset (no stop-m/c)
>>>>>
>>>>> 8 17.04 7.73
>>>>>
>>>>> 16 18.05 6.44
>>>>>
>>>>> 32 17.31 7.39
>>>>>
>>>>> 64 32.40 9.28
>>>>>
>>>>> 128 98.23 7.35
>>>>
>>>> Nice!
>>>
>>> Thank you :-)
>>>
>>>> I wonder how the ARM guys feel with their quad-cpu systems...
>>>>
>>>
>>> That would be definitely interesting to know :-)
>>
>> That depends what exactly you'd like tested (and how) and whether you'd
>> like it to be a test-chip based quad core, or an OMAP dual-core SoC.
>>
>
> The effect of stop_machine() doesn't really depend on the CPU architecture
> used underneath or the platform. It depends only on the _number_ of
> _logical_ CPUs used.
>
> And stop_machine() has 2 noticeable drawbacks:
> 1. It makes the hotplug operation itself slow
> 2. and it causes disruptions to the workloads running on the other
> CPUs by hijacking the entire machine for significant amounts of time.
>
> In my experiments (mentioned above), I tried to measure how my patchset
> improves (reduces) the duration of hotplug (CPU offline) itself. Which is
> also slightly indicative of the impact it has on the rest of the system.
>
> But what would be nice to test, is a setup where the workloads running on
> the rest of the system are latency-sensitive, and measure the impact of
> CPU offline on them, with this patchset applied. That would tell us how
> far is this useful in making CPU hotplug less disruptive on the system.
>
> Of course, it would be nice to also see whether we observe any reduction
> in hotplug duration itself (point 1 above) on ARM platforms with lot
> of CPUs. [This could potentially speed up suspend/resume, which is used
> rather heavily on ARM platforms].
>
> The benefits from this patchset over mainline (both in terms of points
> 1 and 2 above) is expected to increase, with increasing number of CPUs in
> the system.
>
Adding Vincent to CC, who had previously evaluated the performance and
latency implications of CPU hotplug on ARM platforms, IIRC.
Regards,
Srivatsa S. Bhat
next prev parent reply other threads:[~2013-02-08 18:12 UTC|newest]
Thread overview: 122+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-22 7:33 [PATCH v5 00/45] CPU hotplug: stop_machine()-free CPU hotplug Srivatsa S. Bhat
2013-01-22 7:33 ` [PATCH v5 01/45] percpu_rwlock: Introduce the global reader-writer lock backend Srivatsa S. Bhat
2013-01-22 18:45 ` Stephen Hemminger
2013-01-22 19:41 ` Srivatsa S. Bhat
2013-01-22 19:32 ` Steven Rostedt
2013-01-22 19:58 ` Srivatsa S. Bhat
2013-01-22 20:54 ` Steven Rostedt
2013-01-24 4:14 ` Michel Lespinasse
2013-01-24 15:58 ` Oleg Nesterov
2013-01-22 7:33 ` [PATCH v5 02/45] percpu_rwlock: Introduce per-CPU variables for the reader and the writer Srivatsa S. Bhat
2013-01-22 7:33 ` [PATCH v5 03/45] percpu_rwlock: Provide a way to define and init percpu-rwlocks at compile time Srivatsa S. Bhat
2013-01-22 7:33 ` [PATCH v5 04/45] percpu_rwlock: Implement the core design of Per-CPU Reader-Writer Locks Srivatsa S. Bhat
2013-01-23 18:55 ` Tejun Heo
2013-01-23 19:33 ` Srivatsa S. Bhat
2013-01-23 19:57 ` Tejun Heo
2013-01-24 4:30 ` Srivatsa S. Bhat
2013-01-29 11:12 ` Namhyung Kim
2013-02-08 22:47 ` Paul E. McKenney
2013-02-10 18:38 ` Srivatsa S. Bhat
2013-02-08 23:10 ` Paul E. McKenney
2013-02-10 18:06 ` Oleg Nesterov
2013-02-10 19:24 ` Srivatsa S. Bhat
2013-02-10 19:50 ` Oleg Nesterov
2013-02-10 20:09 ` Srivatsa S. Bhat
2013-02-10 22:13 ` Paul E. McKenney
2013-02-10 19:54 ` Paul E. McKenney
2013-02-12 16:15 ` Paul E. McKenney
2013-02-10 19:10 ` Srivatsa S. Bhat
2013-02-10 19:47 ` Paul E. McKenney
2013-02-10 19:57 ` Srivatsa S. Bhat
2013-02-10 20:13 ` Oleg Nesterov
2013-02-10 20:20 ` Srivatsa S. Bhat
2013-01-22 7:34 ` [PATCH v5 05/45] percpu_rwlock: Make percpu-rwlocks IRQ-safe, optimally Srivatsa S. Bhat
2013-02-08 23:44 ` Paul E. McKenney
2013-02-10 19:27 ` Srivatsa S. Bhat
2013-02-10 18:42 ` Oleg Nesterov
2013-02-10 19:30 ` Srivatsa S. Bhat
2013-01-22 7:34 ` [PATCH v5 06/45] percpu_rwlock: Allow writers to be readers, and add lockdep annotations Srivatsa S. Bhat
2013-02-08 23:47 ` Paul E. McKenney
2013-02-10 19:32 ` Srivatsa S. Bhat
2013-01-22 7:34 ` [PATCH v5 07/45] CPU hotplug: Provide APIs to prevent CPU offline from atomic context Srivatsa S. Bhat
2013-01-29 10:21 ` Namhyung Kim
2013-02-10 19:34 ` Srivatsa S. Bhat
2013-02-08 23:50 ` Paul E. McKenney
2013-01-22 7:35 ` [PATCH v5 08/45] CPU hotplug: Convert preprocessor macros to static inline functions Srivatsa S. Bhat
2013-02-08 23:51 ` Paul E. McKenney
2013-01-22 7:35 ` [PATCH v5 09/45] smp, cpu hotplug: Fix smp_call_function_*() to prevent CPU offline properly Srivatsa S. Bhat
2013-02-09 0:07 ` Paul E. McKenney
2013-02-10 19:41 ` Srivatsa S. Bhat
2013-02-10 19:56 ` Paul E. McKenney
2013-02-10 19:59 ` Srivatsa S. Bhat
2013-01-22 7:35 ` [PATCH v5 10/45] smp, cpu hotplug: Fix on_each_cpu_*() " Srivatsa S. Bhat
2013-01-22 7:35 ` [PATCH v5 11/45] sched/timer: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:35 ` [PATCH v5 12/45] sched/migration: Use raw_spin_lock/unlock since interrupts are already disabled Srivatsa S. Bhat
2013-01-22 7:36 ` [PATCH v5 13/45] sched/rt: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:36 ` [PATCH v5 14/45] rcu, CPU hotplug: Fix comment referring to stop_machine() Srivatsa S. Bhat
2013-02-09 0:14 ` Paul E. McKenney
2013-02-10 19:43 ` Srivatsa S. Bhat
2013-01-22 7:36 ` [PATCH v5 15/45] tick: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:37 ` [PATCH v5 16/45] time/clocksource: " Srivatsa S. Bhat
2013-01-22 7:37 ` [PATCH v5 17/45] softirq: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 18/45] irq: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 19/45] net: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 20/45] block: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 21/45] crypto: pcrypt - Protect access to cpu_online_mask with get/put_online_cpus() Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 22/45] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 23/45] [SCSI] fcoe: " Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 24/45] staging: octeon: " Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 25/45] x86: " Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 26/45] perf/x86: " Srivatsa S. Bhat
2013-01-22 7:40 ` [PATCH v5 27/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline from atomic context Srivatsa S. Bhat
2013-01-22 7:40 ` [PATCH v5 28/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:40 ` [PATCH v5 29/45] x86/xen: " Srivatsa S. Bhat
2013-02-19 18:10 ` Konrad Rzeszutek Wilk
2013-02-19 18:29 ` Srivatsa S. Bhat
2013-01-22 7:41 ` [PATCH v5 30/45] alpha/smp: " Srivatsa S. Bhat
2013-01-22 7:41 ` [PATCH v5 31/45] blackfin/smp: " Srivatsa S. Bhat
2013-01-28 9:09 ` Bob Liu
2013-01-28 19:06 ` Tejun Heo
2013-01-29 1:14 ` Srivatsa S. Bhat
2013-01-22 7:41 ` [PATCH v5 32/45] cris/smp: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 33/45] hexagon/smp: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 34/45] ia64: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 35/45] m32r: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 36/45] MIPS: " Srivatsa S. Bhat
2013-01-22 7:43 ` [PATCH v5 37/45] mn10300: " Srivatsa S. Bhat
2013-01-22 7:43 ` [PATCH v5 38/45] parisc: " Srivatsa S. Bhat
2013-01-22 7:43 ` [PATCH v5 39/45] powerpc: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 40/45] sh: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 41/45] sparc: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 42/45] tile: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 43/45] cpu: No more __stop_machine() in _cpu_down() Srivatsa S. Bhat
2013-01-22 7:45 ` [PATCH v5 44/45] CPU hotplug, stop_machine: Decouple CPU hotplug from stop_machine() in Kconfig Srivatsa S. Bhat
2013-02-09 0:15 ` Paul E. McKenney
2013-02-10 19:45 ` Srivatsa S. Bhat
2013-01-22 7:45 ` [PATCH v5 45/45] Documentation/cpu-hotplug: Remove references to stop_machine() Srivatsa S. Bhat
2013-02-09 0:16 ` Paul E. McKenney
2013-02-04 13:47 ` [PATCH v5 00/45] CPU hotplug: stop_machine()-free CPU hotplug Srivatsa S. Bhat
2013-02-07 4:14 ` Rusty Russell
2013-02-07 6:11 ` Srivatsa S. Bhat
2013-02-08 15:41 ` Russell King - ARM Linux
2013-02-08 16:44 ` Srivatsa S. Bhat
2013-02-08 18:09 ` Srivatsa S. Bhat [this message]
2013-02-11 11:58 ` Vincent Guittot
2013-02-11 12:23 ` Srivatsa S. Bhat
2013-02-11 19:08 ` Paul E. McKenney
2013-02-12 3:58 ` Srivatsa S. Bhat
2013-02-15 13:28 ` Vincent Guittot
2013-02-15 19:40 ` Srivatsa S. Bhat
2013-02-18 10:24 ` Vincent Guittot
2013-02-18 10:34 ` Srivatsa S. Bhat
2013-02-18 10:51 ` Srivatsa S. Bhat
2013-02-18 10:58 ` Vincent Guittot
2013-02-18 15:30 ` Steven Rostedt
2013-02-18 16:50 ` Vincent Guittot
2013-02-18 19:53 ` Steven Rostedt
2013-02-18 19:53 ` Steven Rostedt
2013-02-19 10:33 ` Vincent Guittot
2013-02-18 10:54 ` Thomas Gleixner
2013-02-18 10:57 ` Srivatsa S. Bhat
2013-02-11 12:41 ` [PATCH v5 01/45] percpu_rwlock: Introduce the global reader-writer lock backend David Howells
2013-02-11 12:56 ` Srivatsa S. Bhat
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