Commit 5d7107c7 authored May 26, 2023 by Jonathan Cameron Committed by Dan Williams Jun 25, 2023

perf: CXL Performance Monitoring Unit driver



CXL rev 3.0 introduces a standard performance monitoring hardware
block to CXL. Instances are discovered using CXL Register Locator DVSEC
entries. Each CXL component may have multiple PMUs.

This initial driver supports a subset of types of counter.
It supports counters that are either fixed or configurable, but requires
that they support the ability to freeze and write value whilst frozen.

Development done with QEMU model which will be posted shortly.

Example:

$ perf stat -a -e cxl_pmu_mem0.0/h2d_req_snpcur/ -e cxl_pmu_mem0.0/h2d_req_snpdata/ -e cxl_pmu_mem0.0/clock_ticks/ sleep 1

Performance counter stats for 'system wide':

96,757,023,244,321      cxl_pmu_mem0.0/h2d_req_snpcur/
96,757,023,244,365      cxl_pmu_mem0.0/h2d_req_snpdata/
193,514,046,488,653      cxl_pmu_mem0.0/clock_ticks/

       1.090539600 seconds time elapsed

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230526095824.16336-5-Jonathan.Cameron@huawei.com


Signed-off-by: Dan Williams <dan.j.williams@intel.com>

parent 1ad3f701

MAINTAINERS

+6 −0

Original line number	Diff line number	Diff line
		@@ -5193,6 +5193,12 @@ S: Maintained
		F: drivers/cxl/
		F: include/uapi/linux/cxl_mem.h

		COMPUTE EXPRESS LINK PMU (CPMU)
		M: Jonathan Cameron <jonathan.cameron@huawei.com>
		L: linux-cxl@vger.kernel.org
		S: Maintained
		F: drivers/perf/cxl_pmu.c

		CONEXANT ACCESSRUNNER USB DRIVER
		L: accessrunner-general@lists.sourceforge.net
		S: Orphan

drivers/cxl/Kconfig

+13 −0

Original line number	Diff line number	Diff line
		@@ -139,4 +139,17 @@ config CXL_REGION_INVALIDATION_TEST
		If unsure, or if this kernel is meant for production environments,
		say N.

		config CXL_PMU
		tristate "CXL Performance Monitoring Unit"
		default CXL_BUS
		depends on PERF_EVENTS
		help
		Support performance monitoring as defined in CXL rev 3.0
		section 13.2: Performance Monitoring. CXL components may have
		one or more CXL Performance Monitoring Units (CPMUs).

		Say 'y/m' to enable a driver that will attach to performance
		monitoring units and provide standard perf based interfaces.

		If unsure say 'm'.
		endif

drivers/perf/Kconfig

+13 −0

Original line number	Diff line number	Diff line
		@@ -213,4 +213,17 @@ source "drivers/perf/arm_cspmu/Kconfig"

		source "drivers/perf/amlogic/Kconfig"

		config CXL_PMU
		tristate "CXL Performance Monitoring Unit"
		depends on CXL_BUS
		help
		Support performance monitoring as defined in CXL rev 3.0
		section 13.2: Performance Monitoring. CXL components may have
		one or more CXL Performance Monitoring Units (CPMUs).

		Say 'y/m' to enable a driver that will attach to performance
		monitoring units and provide standard perf based interfaces.

		If unsure say 'm'.

		endmenu

drivers/perf/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -24,3 +24,4 @@ obj-$(CONFIG_APPLE_M1_CPU_PMU) += apple_m1_cpu_pmu.o
		obj-$(CONFIG_ALIBABA_UNCORE_DRW_PMU) += alibaba_uncore_drw_pmu.o
		obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += arm_cspmu/
		obj-$(CONFIG_MESON_DDR_PMU) += amlogic/
		obj-$(CONFIG_CXL_PMU) += cxl_pmu.o

drivers/perf/cxl_pmu.c

0 → 100644

+990 −0

File added.

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