Stephane Eranian 11745ecfe8 perf/x86/intel/uncore: Fix broken read_counter() for SNB IMC PMU ... Existing code was generating bogus counts for the SNB IMC bandwidth counters: $ perf stat -a -I 1000 -e uncore_imc/data_reads/,uncore_imc/data_writes/ 1.000327813 1,024.03 MiB uncore_imc/data_reads/ 1.000327813 20.73 MiB uncore_imc/data_writes/ 2.000580153 261,120.00 MiB uncore_imc/data_reads/ 2.000580153 23.28 MiB uncore_imc/data_writes/ The problem was introduced by commit: 07ce734dd8 ("perf/x86/intel/uncore: Clean up client IMC") Where the read_counter callback was replace to point to the generic uncore_mmio_read_counter() function. The SNB IMC counters are freerunnig 32-bit counters laid out contiguously in MMIO. But uncore_mmio_read_counter() is using a readq() call to read from MMIO therefore reading 64-bit from MMIO. Although this is okay for the uncore_perf_event_update() function because it is shifting the value based on the actual counter width to compute a delta, it is not okay for the uncore_pmu_event_start() which is simply reading the counter and therefore priming the event->prev_count with a bogus value which is responsible for causing bogus deltas in the perf stat command above. The fix is to reintroduce the custom callback for read_counter for the SNB IMC PMU and use readl() instead of readq(). With the change the output of perf stat is back to normal: $ perf stat -a -I 1000 -e uncore_imc/data_reads/,uncore_imc/data_writes/ 1.000120987 296.94 MiB uncore_imc/data_reads/ 1.000120987 138.42 MiB uncore_imc/data_writes/ 2.000403144 175.91 MiB uncore_imc/data_reads/ 2.000403144 68.50 MiB uncore_imc/data_writes/ Fixes: 07ce734dd8 ("perf/x86/intel/uncore: Clean up client IMC") Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20220803160031.1379788-1-eranian@google.com		2022-08-27 00:05:38 +02:00
..
bts.c	perf/x86: Add compiler barrier after updating BTS	2021-09-17 15:08:38 +02:00
core.c	perf/x86/core: Set pebs_capable and PMU_FL_PEBS_ALL for the Baseline	2022-08-19 19:47:31 +02:00
cstate.c	perf/x86/cstate: Add new Alder Lake and Raptor Lake support	2022-05-11 16:27:08 +02:00
ds.c	perf/x86/intel: Fix pebs event constraints for ADL	2022-08-19 19:47:31 +02:00
knc.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
lbr.c	perf/x86/lbr: Enable the branch type for the Arch LBR by default	2022-08-19 19:47:30 +02:00
Makefile	perf/x86/intel/uncore: Parse uncore discovery tables	2021-04-02 10:04:54 +02:00
p4.c	Perf events changes in this cycle were:	2021-04-28 13:03:44 -07:00
p6.c	x86/cpu: Rename cpu_data.x86_mask to cpu_data.x86_stepping	2018-02-15 01:15:52 +01:00
pt.c	Changes for this cycle were:	2022-03-22 13:06:49 -07:00
pt.h	perf/x86/intel/pt: Prevent redundant WRMSRs	2019-11-13 11:06:18 +01:00
uncore_discovery.c	perf/x86/intel/uncore: Fix the build on !CONFIG_PHYS_ADDR_T_64BIT	2022-03-03 08:58:22 +01:00
uncore_discovery.h	perf/x86/intel/uncore: Make uncore_discovery clean for 64 bit addresses	2022-03-01 16:19:01 +01:00
uncore_nhmex.c	perf/x86/intel/uncore: Correct fixed counter index check for NHM	2018-05-31 12:36:28 +02:00
uncore_snb.c	perf/x86/intel/uncore: Fix broken read_counter() for SNB IMC PMU	2022-08-27 00:05:38 +02:00
uncore_snbep.c	perf/x86/intel/uncore: Fix CAS_COUNT_WRITE issue for ICX	2022-01-18 12:09:48 +01:00
uncore.c	perf/x86/uncore: Add new Alder Lake and Raptor Lake support	2022-05-11 16:27:09 +02:00
uncore.h	perf/x86/intel/uncore: Add IMC uncore support for ADL	2022-01-18 12:09:49 +01:00