Patch "perf/x86/amd: Make HW_CACHE_REFERENCES and HW_CACHE_MISSES measure L2" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

perf/x86/amd: Make HW_CACHE_REFERENCES and HW_CACHE_MISSES measure L2

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
perf-x86-amd-make-hw_cache_references-and-hw_cache_misses-measure-l2.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Matt Fleming <[email protected]>
Date: Wed, 24 Aug 2016 14:12:08 +0100
Subject: perf/x86/amd: Make HW_CACHE_REFERENCES and HW_CACHE_MISSES measure L2

From: Matt Fleming <[email protected]>

commit 080fe0b790ad438fc1b61621dac37c1964ce7f35 upstream.

While the Intel PMU monitors the LLC when perf enables the HW_CACHE_REFERENCES and HW_CACHE_MISSES events, these events monitor L1 instruction cache fetches (0x0080) and instruction cache misses (0x0081) on the AMD PMU.

This is extremely confusing when monitoring the same workload across Intel and AMD machines, since parameters like,

  $ perf stat -e cache-references,cache-misses

measure completely different things.

Instead, make the AMD PMU measure instruction/data cache and TLB fill requests to the L2 and instruction/data cache and TLB misses in the L2 when HW_CACHE_REFERENCES and HW_CACHE_MISSES are enabled, respectively. That way the events measure unified caches on both platforms.

---
 arch/x86/events/amd/core.c |    4 ++--
 arch/x86/kvm/pmu_amd.c     |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

@@ -119,8 +119,8 @@ static const u64 amd_perfmon_event_map[P
 {
   [PERF_COUNT_HW_CPU_CYCLES]			= 0x0076,
   [PERF_COUNT_HW_INSTRUCTIONS]			= 0x00c0,
-  [PERF_COUNT_HW_CACHE_REFERENCES]		= 0x0080,
-  [PERF_COUNT_HW_CACHE_MISSES]			= 0x0081,
+  [PERF_COUNT_HW_CACHE_REFERENCES]		= 0x077d,
+  [PERF_COUNT_HW_CACHE_MISSES]			= 0x077e,
   [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]		= 0x00c2,
   [PERF_COUNT_HW_BRANCH_MISSES]			= 0x00c3,
   [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= 0x00d0, /* "Decoder empty" event */

@@ -23,8 +23,8 @@
 static struct kvm_event_hw_type_mapping amd_event_mapping[] = {
 	[0] = { 0x76, 0x00, PERF_COUNT_HW_CPU_CYCLES },
 	[1] = { 0xc0, 0x00, PERF_COUNT_HW_INSTRUCTIONS },
-	[2] = { 0x80, 0x00, PERF_COUNT_HW_CACHE_REFERENCES },
-	[3] = { 0x81, 0x00, PERF_COUNT_HW_CACHE_MISSES },
+	[2] = { 0x7d, 0x07, PERF_COUNT_HW_CACHE_REFERENCES },
+	[3] = { 0x7e, 0x07, PERF_COUNT_HW_CACHE_MISSES },
 	[4] = { 0xc2, 0x00, PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
 	[5] = { 0xc3, 0x00, PERF_COUNT_HW_BRANCH_MISSES },
 	[6] = { 0xd0, 0x00, PERF_COUNT_HW_STALLED_CYCLES_FRONTEND },

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/efi-libstub-allocate-headspace-in-efi_get_memory_map.patch queue-4.7/x86-efi-use-efi_exit_boot_services.patch queue-4.7/efi-libstub-introduce-exitbootservices-helper.patch queue-4.7/efi-libstub-use-efi_exit_boot_services-in-fdt.patch queue-4.7/perf-x86-amd-make-hw_cache_references-and-hw_cache_misses-measure-l2.patch queue-4.7/efi-make-for_each_efi_memory_desc_in_map-cope-with-running-on-xen.patch