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Subject[PATCH V5 1/8] perf/x86/intel/uncore: customized event_read for client IMC uncore
Date
From: Kan Liang <Kan.liang@intel.com>

There are two free running counters for client IMC uncore. The custom
event_init() function hardcode their index to 'UNCORE_PMC_IDX_FIXED' and
'UNCORE_PMC_IDX_FIXED + 1'. To support the 'UNCORE_PMC_IDX_FIXED + 1'
case, the generic uncore_perf_event_update is obscurely hacked.
The code quality issue will bring problem when new counter index is
introduced into generic code. For example, free running counter index.

Introduce customized event_read function for client IMC uncore.
The customized function is exactly copied from previous generic
uncore_pmu_event_read.
The 'UNCORE_PMC_IDX_FIXED + 1' case will be isolated for client IMC
uncore only.

Signed-off-by: Kan Liang <Kan.liang@intel.com>
---

No changes since V4

arch/x86/events/intel/uncore_snb.c | 33 +++++++++++++++++++++++++++++++--
1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/uncore_snb.c b/arch/x86/events/intel/uncore_snb.c
index aee5e84..df53521 100644
--- a/arch/x86/events/intel/uncore_snb.c
+++ b/arch/x86/events/intel/uncore_snb.c
@@ -450,6 +450,35 @@ static void snb_uncore_imc_event_start(struct perf_event *event, int flags)
uncore_pmu_start_hrtimer(box);
}

+static void snb_uncore_imc_event_read(struct perf_event *event)
+{
+ struct intel_uncore_box *box = uncore_event_to_box(event);
+ u64 prev_count, new_count, delta;
+ int shift;
+
+ /*
+ * There are two free running counters in IMC.
+ * The index for the second one is hardcoded to
+ * UNCORE_PMC_IDX_FIXED + 1.
+ */
+ if (event->hw.idx >= UNCORE_PMC_IDX_FIXED)
+ shift = 64 - uncore_fixed_ctr_bits(box);
+ else
+ shift = 64 - uncore_perf_ctr_bits(box);
+
+ /* the hrtimer might modify the previous event value */
+again:
+ prev_count = local64_read(&event->hw.prev_count);
+ new_count = uncore_read_counter(box, event);
+ if (local64_xchg(&event->hw.prev_count, new_count) != prev_count)
+ goto again;
+
+ delta = (new_count << shift) - (prev_count << shift);
+ delta >>= shift;
+
+ local64_add(delta, &event->count);
+}
+
static void snb_uncore_imc_event_stop(struct perf_event *event, int flags)
{
struct intel_uncore_box *box = uncore_event_to_box(event);
@@ -472,7 +501,7 @@ static void snb_uncore_imc_event_stop(struct perf_event *event, int flags)
* Drain the remaining delta count out of a event
* that we are disabling:
*/
- uncore_perf_event_update(box, event);
+ snb_uncore_imc_event_read(event);
hwc->state |= PERF_HES_UPTODATE;
}
}
@@ -534,7 +563,7 @@ static struct pmu snb_uncore_imc_pmu = {
.del = snb_uncore_imc_event_del,
.start = snb_uncore_imc_event_start,
.stop = snb_uncore_imc_event_stop,
- .read = uncore_pmu_event_read,
+ .read = snb_uncore_imc_event_read,
};

static struct intel_uncore_ops snb_uncore_imc_ops = {
--
2.7.4
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