| Message ID | 20240223103359.18669-7-yangyicong@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drivers/perf: hisi_pcie: Several updates for HiSilicon PCIe PMU driver | expand |
On Fri, 23 Feb 2024 18:33:57 +0800 Yicong Yang <yangyicong@huawei.com> wrote: > From: Junhao He <hejunhao3@huawei.com> > > If we use two events with the same filter and related event type > (see the following example), the driver check whether they are related > events and are in the same group, otherwise the function > hisi_pcie_pmu_find_related_event() return -EINVAL, then the 2nd event > cannot count but the 1st event is running, although the PCIe PMU has > other idle counters. > > In this case, The perf event scheduler will make the two events to > multiplex a counter, if the user use the formula > (1st event_value / 2nd event_value) to calculate the bandwidth, he/she > won't get the correct value, because they are not counting at the > same period. > > This patch tries to fix this by making the related events to use > different idle counters if they are not in the same event group. > > And finally, I'm going to say. The related events are best used in the > same group [1]. There are two ways to know if they are related events. > a) By event name, such as the latency events "xxx_latency, xxx_cnt" or > bandwidth events "xxx_flux, xxx_time". > b) By event type, such as "event=0xXXXX, event=0x1XXXX". > > Use group to count the related events: > [1] -e "{pmu_name/xxx_latency,port=1/,pmu_name/xxx_cnt,port=1/}" > > example: > 1st event: hisi_pcie0_core1/event=0x804,port=1 > 2nd event: hisi_pcie0_core1/event=0x10804,port=1 > > test cmd: > perf stat -e hisi_pcie0_core1/event=0x804,port=1/ \ > -e hisi_pcie0_core1/event=0x10804,port=1/ > > before patch: > 25,281 hisi_pcie0_core1/event=0x804,port=1/ (49.91%) > 470,598 hisi_pcie0_core1/event=0x10804,port=1/ (50.09%) > > after patch: > 24,147 hisi_pcie0_core1/event=0x804,port=1/ > 474,558 hisi_pcie0_core1/event=0x10804,port=1/ > > Signed-off-by: Junhao He <hejunhao3@huawei.com> > Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huwei.com> > --- > drivers/perf/hisilicon/hisi_pcie_pmu.c | 8 ++------ > 1 file changed, 2 insertions(+), 6 deletions(-) > > diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c > index b2dde7559639..5b15f3698188 100644 > --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c > +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c > @@ -409,14 +409,10 @@ static int hisi_pcie_pmu_find_related_event(struct hisi_pcie_pmu *pcie_pmu, > if (!sibling) > continue; > > - if (!hisi_pcie_pmu_cmp_event(sibling, event)) > - continue; > - > /* Related events must be used in group */ > - if (sibling->group_leader == event->group_leader) > + if (hisi_pcie_pmu_cmp_event(sibling, event) && > + sibling->group_leader == event->group_leader) > return idx; > - else > - return -EINVAL; > } > > return idx;
diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c index b2dde7559639..5b15f3698188 100644 --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c @@ -409,14 +409,10 @@ static int hisi_pcie_pmu_find_related_event(struct hisi_pcie_pmu *pcie_pmu, if (!sibling) continue; - if (!hisi_pcie_pmu_cmp_event(sibling, event)) - continue; - /* Related events must be used in group */ - if (sibling->group_leader == event->group_leader) + if (hisi_pcie_pmu_cmp_event(sibling, event) && + sibling->group_leader == event->group_leader) return idx; - else - return -EINVAL; } return idx;