Messages in this thread | | | Date | Mon, 27 Mar 2023 15:10:55 +0100 | From | Will Deacon <> | Subject | Re: [PATCH 2/3] perf/amlogic: Fix large number of counter issue |
| |
On Thu, Feb 09, 2023 at 07:54:02PM +0800, Jiucheng Xu wrote: > When use 1ms interval, very large number of counter happens > once in a while as below: > > 25.968654513 281474976710655.84 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/ > 26.118657346 281474976710655.88 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/ > 26.180137180 281474976710655.66 MB meson_ddr_bw/chan_1_rw_bytes,arm=1/ > > Root cause is the race between irq handler > and pmu.read callback. Use spin lock to protect the sw&hw > counters. > > Signed-off-by: Jiucheng Xu <jiucheng.xu@amlogic.com> > --- > drivers/perf/amlogic/meson_ddr_pmu_core.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/perf/amlogic/meson_ddr_pmu_core.c b/drivers/perf/amlogic/meson_ddr_pmu_core.c > index 0b24dee1ed3c..9b2e5d5c0626 100644 > --- a/drivers/perf/amlogic/meson_ddr_pmu_core.c > +++ b/drivers/perf/amlogic/meson_ddr_pmu_core.c > @@ -14,6 +14,7 @@ > #include <linux/perf_event.h> > #include <linux/platform_device.h> > #include <linux/printk.h> > +#include <linux/spinlock.h> > #include <linux/sysfs.h> > #include <linux/types.h> > > @@ -23,6 +24,7 @@ struct ddr_pmu { > struct pmu pmu; > struct dmc_info info; > struct dmc_counter counters; /* save counters from hw */ > + spinlock_t lock; /* protect hw/sw counter */ > bool pmu_enabled; > struct device *dev; > char *name; > @@ -92,10 +94,12 @@ static void meson_ddr_perf_event_update(struct perf_event *event) > int idx; > int chann_nr = pmu->info.hw_info->chann_nr; > > + spin_lock(&pmu->lock);
Why doesn't this need the _irqsave() variant if we're racing with the irq handler?
Will
| |