[PATCH V4 1/8] perf/x86/intel/uncore: customized event_read for client IMC uncore

[kan . liang]

From: Kan Liang <kan.li...@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.li...@intel.com>
---

Change since V3:
 - Use the customized read function to replace uncore_perf_event_update.
 - Move generic code change to patch 3/8.

 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 db1127c..b6d0d72 100644
--- a/arch/x86/events/intel/uncore_snb.c
+++ b/arch/x86/events/intel/uncore_snb.c
@@ -449,6 +449,35 @@ 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);
@@ -471,7 +500,7 @@ 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;
        }
 }
@@ -533,7 +562,7 @@ 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