Re: [PATCH v2 2/2] perf/x86/intel: force resched when TFA sysctl is modified

2019-04-15 Thread Stephane Eranian
On Mon, Apr 15, 2019 at 8:57 AM Peter Zijlstra wrote: > > On Mon, Apr 08, 2019 at 10:32:52AM -0700, Stephane Eranian wrote: > > +static ssize_t set_sysctl_tfa(struct device *cdev, > > + struct device_attribute *attr, > > + const char *buf, size_t

Re: [PATCH v2 2/2] perf/x86/intel: force resched when TFA sysctl is modified

2019-04-15 Thread Peter Zijlstra
On Mon, Apr 08, 2019 at 10:32:52AM -0700, Stephane Eranian wrote: > +static ssize_t set_sysctl_tfa(struct device *cdev, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + bool val; > + ssize_t ret; > + > + r

[PATCH v2 2/2] perf/x86/intel: force resched when TFA sysctl is modified

2019-04-08 Thread Stephane Eranian
This patch provides guarantee to the sysadmin that when TFA is disabled, no PMU event is using PMC3 when the echo command returns. Vice-Versa, when TFA is enabled, PMU can use PMC3 immediately (to eliminate possible multiplexing). $ perf stat -a -I 1000 --no-merge -e branches,branches,branches,bra