Messages in this thread |  | | Subject | Re: [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU | From | Christophe Leroy <> | Date | Wed, 5 Feb 2020 08:08:46 +0100 |
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Le 27/11/2019 à 13:01, Gautham R. Shenoy a écrit : > From: "Gautham R. Shenoy" <ego@linux.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 ?
Christophe
> > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> > --- > arch/powerpc/kernel/sysfs.c | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c > index 80a676d..42ade55 100644 > --- a/arch/powerpc/kernel/sysfs.c > +++ b/arch/powerpc/kernel/sysfs.c > @@ -1044,6 +1044,36 @@ static ssize_t show_physical_id(struct device *dev, > } > static DEVICE_ATTR(physical_id, 0444, show_physical_id, NULL); > > +static ssize_t idle_purr_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct cpu *cpu = container_of(dev, struct cpu, dev); > + unsigned int cpuid = cpu->dev.id; > + struct lppaca *cpu_lppaca_ptr = paca_ptrs[cpuid]->lppaca_ptr; > + u64 idle_purr_cycles = be64_to_cpu(cpu_lppaca_ptr->wait_state_cycles); > + > + return sprintf(buf, "%llx\n", idle_purr_cycles); > +} > +static DEVICE_ATTR_RO(idle_purr); > + > +DECLARE_PER_CPU(u64, idle_spurr_cycles); > +static ssize_t idle_spurr_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct cpu *cpu = container_of(dev, struct cpu, dev); > + unsigned int cpuid = cpu->dev.id; > + u64 *idle_spurr_cycles_ptr = per_cpu_ptr(&idle_spurr_cycles, cpuid); > + > + return sprintf(buf, "%llx\n", *idle_spurr_cycles_ptr); > +} > +static DEVICE_ATTR_RO(idle_spurr); > + > +static void create_idle_purr_spurr_sysfs_entry(struct device *cpudev) > +{ > + device_create_file(cpudev, &dev_attr_idle_purr); > + device_create_file(cpudev, &dev_attr_idle_spurr); > +} > + > static int __init topology_init(void) > { > int cpu, r; > @@ -1067,6 +1097,8 @@ static int __init topology_init(void) > register_cpu(c, cpu); > > device_create_file(&c->dev, &dev_attr_physical_id); > + if (firmware_has_feature(FW_FEATURE_SPLPAR)) > + create_idle_purr_spurr_sysfs_entry(&c->dev); > } > } > r = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/topology:online", >
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