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Date: Mon, 23 Jan 2017 12:18:07 -0800 (PST) From: Shivappa Vikas <vikas.shivappa@...el.com> To: Thomas Gleixner <tglx@...utronix.de> cc: Vikas Shivappa <vikas.shivappa@...ux.intel.com>, vikas.shivappa@...el.com, linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com, mingo@...nel.org, peterz@...radead.org, ravi.v.shankar@...el.com, tony.luck@...el.com, fenghua.yu@...el.com, h.peter.anvin@...el.com Subject: Re: [PATCH 8/8] x86/intel_rdt: rmdir,umount and hotcpu updates for MBA On Mon, 16 Jan 2017, Thomas Gleixner wrote: > On Tue, 10 Jan 2017, Vikas Shivappa wrote: > >> During rmdir only reset the ctrl values for the rdtgroup's closid. This >> is done so that that next time when the closid is reused they dont >> reflect old values. > > How on earth is that related to MBA? This is not specific to MBA so i put it as x86/intel_rdt in the subject but will send this as part of seperate series which you mentioned. > >> Remove the closid update during cpuonline in cqm as its >> already in the CAT code. Since both cqm and CAT want the rmid and closid >> to be zero when cpu is online, remove the PQR MSR write to zero during >> cpuonline because the MSRs are at zero after cpu reset and also during > > Are you sure that the MSRs are zero when the cpu goes offline and then > online again? That's not a reset. Thats right - I was removing this since at the first sched_in the new CLOSID would be updated anyways. I know this prevents from having a 0 CLOSid at the time all the hot plug code is run, but we already have run the __cpu_disable and all the hotplug code when going down on the last used CLOSid. (if the kernel thread that handles the offline/online should have a 0 CLOS then thats fine probably..) So may be the right way is to actually zero the CLOS in PQR_MSR when we are going down/offline ? Thanks, Vikas > > Thanks, > > tglx >
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