Hi Peter, > -----Original Message----- > From: Peter Zijlstra [mailto:[email protected]] > Sent: 18 августа 2015 г. 20:52 > To: Alexey Brodkin > Cc: [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; Arnaldo Carvalho de Melo > Subject: Re: [PATCH v2 3/8] ARCv2: perf: implement "event_set_period" for > future use with interrupts > > On Wed, Aug 05, 2015 at 06:13:29PM +0300, Alexey Brodkin wrote: > > Even though this hardware implementation allows for more flexibility, > > in Linux kernel we decided to mimic behavior of other architectures this > > way: > > > > [1] Set limit value as half of counter's max value (to allow counter to > > run after reaching it limit, see below for more explanation): > > ---------->8----------- > > arc_pmu->max_period = (1ULL << counter_size) / 2 - 1ULL; > > ---------->8----------- > > > @@ -317,10 +365,11 @@ static int arc_pmu_device_probe(struct > > platform_device *pdev) > > return -ENOMEM; > > > > arc_pmu->n_counters = pct_bcr.c; > > - arc_pmu->counter_size = 32 + (pct_bcr.s << 4); > > + counter_size = 32 + (pct_bcr.s << 4); > > + arc_pmu->max_period = (1ULL << counter_size) - 1ULL; > > > > I don't see that /2 there..
Probably another good solution for that coupl be merging of 2 following patches in one: [1] [PATCH v2 3/8] ARCv2: perf: implement "event_set_period" for future use with interrupts [2] [PATCH v2 5/8] ARCv2: perf: set usable max period as a half of real max period And then comment will become valid. -Alexey -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
