Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline

[PATCH v2 00/45] CPU hotplug: stop_machine()-free CPU hotplug, part 1 · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 01/45] CPU hotplug: Provide APIs to prevent CPU offline from atomic context · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 02/45] CPU hotplug: Clarify the usage of different synchronization APIs · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 03/45] Documentation, CPU hotplug: Recommend usage of get/put_online_cpus_atomic() · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 04/45] CPU hotplug: Add infrastructure to check lacking hotplug synchronization · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 05/45] CPU hotplug: Protect set_cpu_online() to avoid false-positives · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 07/45] CPU hotplug: Expose the new debug config option · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 08/45] CPU hotplug: Convert preprocessor macros to static inline functions · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 09/45] smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 10/45] sched/core: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 12/45] sched/fair: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 11/45] migration: Use raw_spin_lock/unlock since interrupts are already disabled · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 13/45] timer: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 14/45] sched/rt: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-25
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
RE: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · David Laight <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Steven Rostedt <rostedt@goodmis.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Tejun Heo <tj@kernel.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Steven Rostedt <rostedt@goodmis.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Tejun Heo <tj@kernel.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Tejun Heo <tj@kernel.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-27
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
RE: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · David Laight <hidden> · 2013-06-27
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-27
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-26
[PATCH v2 16/45] tick-broadcast: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 17/45] time/clocksource: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 18/45] softirq: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 19/45] irq: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 20/45] net: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 21/45] block: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 22/45] percpu_counter: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 24/45] [SCSI] fcoe: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 25/45] staging/octeon: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 25/45] staging/octeon: Use get/put_online_cpus_atomic() to prevent CPU offline · Greg Kroah-Hartman <gregkh@linuxfoundation.org> · 2013-06-25
[PATCH v2 27/45] perf/x86: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
[PATCH v2 30/45] x86/xen: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 31/45] alpha/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 32/45] blackfin/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 33/45] cris/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 34/45] hexagon/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 35/45] ia64: irq, perfmon: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 36/45] ia64: smp, tlb: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 37/45] m32r: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU offline · Ralf Baechle <hidden> · 2013-06-26
Re: [PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-27
[PATCH v2 39/45] mn10300: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 40/45] powerpc, irq: Use GFP_ATOMIC allocations in atomic context · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 41/45] powerpc: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 42/45] powerpc: Use get/put_online_cpus_atomic() to avoid false-positive warning · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 43/45] sh: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 44/45] sparc: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 45/45] tile: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 28/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 28/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
[PATCH v2 26/45] x86: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 23/45] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 06/45] CPU hotplug: Sprinkle debugging checks to catch locking bugs · Srivatsa S. Bhat <hidden> · 2013-06-25

From: Steven Rostedt <rostedt@goodmis.org>
Date: 2013-06-26 15:33:48
Also in: linux-arch, linux-pm, linuxppc-dev, lkml

On Wed, 2013-06-26 at 08:21 -0700, Tejun Heo wrote:

On Wed, Jun 26, 2013 at 10:51:11AM -0400, Steven Rostedt wrote:

quoted

It would also increase the latency of CPU-hotunplug operations.

Is that a big deal?

I thought that was the whole deal with this patchset - making cpu
hotunplugs lighter and faster mostly for powersaving.  That said, just
removing stop_machine call would be a pretty good deal and I don't
know how meaningful reducing CPU hotunplug latency is.  Srivatsa?

I thought the whole deal with this patchset was to remove stop_machine
from CPU hotplug. Why halt all CPUs just to remove one? stomp_machine()
is extremely intrusive for the entire system, where as one CPU making
sure all CPUs schedule isn't very intrusive at all.

I didn't think the idea of this patch set was to make CPU hotplug
faster, just less intrusive to the system.

-- Steve

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