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Message-ID: <50C01F9B.1020107@linux.vnet.ibm.com> Date: Thu, 06 Dec 2012 10:01:23 +0530 From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> To: Tejun Heo <tj@...nel.org> CC: tglx@...utronix.de, peterz@...radead.org, paulmck@...ux.vnet.ibm.com, rusty@...tcorp.com.au, mingo@...nel.org, akpm@...ux-foundation.org, namhyung@...nel.org, vincent.guittot@...aro.org, oleg@...hat.com, sbw@....edu, amit.kucheria@...aro.org, rostedt@...dmis.org, rjw@...k.pl, wangyun@...ux.vnet.ibm.com, xiaoguangrong@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [RFC PATCH v2 02/10] CPU hotplug: Provide APIs for "full" atomic readers to prevent CPU offline On 12/06/2012 02:27 AM, Tejun Heo wrote: > Hello, > > On Thu, Dec 06, 2012 at 02:01:35AM +0530, Srivatsa S. Bhat wrote: >> Yes, that _sounds_ sufficient, but IMHO it won't be, in practice. The >> *number* of call-sites that you need to convert from preempt_disable/enable >> to get/put_online_cpus_atomic() won't be too many, however the *frequency* >> of usage of those call-sites can potentially be very high. > > I don't think that will be the case and, even if it is, doing it this > way would make it difficult to tell. The right thing to do is > replacing stop_machine with finer grained percpu locking first. > Refining it further should happen iff that isn't enough and there > isn't an simpler solution. So, let's please do the simple conversion > first. > Hmm, OK, that sounds like a good plan. So I'll drop the "light" and "full" variants for now and work on providing a straight-forward get/put_online_cpus_atomic() APIs. Thank you! Regards, Srivatsa S. Bhat -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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