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Date: Wed, 05 Feb 2020 13:37:45 +0530 From: "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> To: Christophe Leroy <christophe.leroy@....fr>, "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>, Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, Nathan Lynch <nathanl@...ux.ibm.com>, Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>, Tyrel Datwyler <tyreld@...ux.ibm.com> Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org Subject: Re: [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU Christophe Leroy wrote: > > > Le 27/11/2019 à 13:01, Gautham R. Shenoy a écrit : >> From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com> >> >> On Pseries LPARs, to calculate utilization, we need to know the >> [S]PURR ticks when the CPUs were busy or idle. >> >> The total PURR and SPURR ticks are already exposed via the per-cpu >> sysfs files /sys/devices/system/cpu/cpuX/purr and >> /sys/devices/system/cpu/cpuX/spurr. >> >> This patch adds support for exposing the idle PURR and SPURR ticks via >> /sys/devices/system/cpu/cpuX/idle_purr and >> /sys/devices/system/cpu/cpuX/idle_spurr. > > Might be a candid question, but I see in arch/powerpc/kernel/time.c that > PURR/SPURR are already taken into account by the kernel to calculate > utilisation when CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is selected. > > As far as I understand, you are wanting to expose this to userland to > redo the calculation there. What is wrong with the values reported by > the kernel ? As you point out, it is only done with CONFIG_VIRT_CPU_ACCOUNTING_NATIVE, but isn't available with NO_HZ_FULL, which happens to be the distro default nowadays. - Naveen
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