Messages in this thread |  | | Date | Thu, 05 Dec 2019 22:23:58 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU |
| |
Gautham R. Shenoy wrote: > 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. > > 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);
Is it possible for a user to read stale values if a particular cpu is in an extended cede? Is it possible to use smp_call_function_single() to force the cpu out of idle?
- Naveen
|  |