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Date: Mon, 15 Apr 2019 10:20:57 -0700 From: Stephane Eranian <eranian@...gle.com> To: Peter Zijlstra <peterz@...radead.org> Cc: LKML <linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>, Andi Kleen <ak@...ux.intel.com>, "Liang, Kan" <kan.liang@...el.com>, mingo@...e.hu, nelson.dsouza@...el.com, Jiri Olsa <jolsa@...hat.com>, tonyj@...e.com Subject: Re: [PATCH v2 2/2] perf/x86/intel: force resched when TFA sysctl is modified On Mon, Apr 15, 2019 at 8:57 AM Peter Zijlstra <peterz@...radead.org> 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 count) > > +{ > > + bool val; > > + ssize_t ret; > > + > > + ret = kstrtobool(buf, &val); > > + if (ret) > > + return ret; > > + > > + /* no change */ > > + if (val == allow_tsx_force_abort) > > + return count; > > + > > + allow_tsx_force_abort = val; > > + > > + get_online_cpus(); > > + on_each_cpu(update_tfa_sched, NULL, 1); > > + put_online_cpus(); > > + > > + return count; > > +} > > So we care about concurrent writing to that file? Not likely but we care about seeing the effects on event scheduling before the sysctl returns.
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