kernel/tools/perf/util/smt.c, branch linux-6.2.y

perf topology: Add core_wide

2022-10-04T11:55:22Z

It is possible to optimize metrics when all SMT threads (CPUs) on a core are measuring events in system wide mode. For example, TMA metrics defines CORE_CLKS for Sandybrdige as: if SMT is disabled: CPU_CLK_UNHALTED.THREAD if SMT is enabled and recording on all SMT threads: CPU_CLK_UNHALTED.THREAD_ANY / 2 if SMT is enabled and not recording on all SMT threads: (CPU_CLK_UNHALTED.THREAD/2)* (1+CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE/CPU_CLK_UNHALTED.REF_XCLK ) That is two more events are necessary when not gathering counts on all SMT threads. To distinguish all SMT threads on a core vs system wide (all CPUs) call the new property core wide. Add a core wide test that determines the property from user requested CPUs, the topology and system wide. System wide is required as other processes running on a SMT thread will change the counts. Signed-off-by: Ian Rogers Cc: Ahmad Yasin Cc: Alexander Shishkin Cc: Andi Kleen Cc: Caleb Biggers Cc: Florian Fischer Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Kan Liang Cc: Kshipra Bopardikar Cc: Mark Rutland Cc: Miaoqian Lin Cc: Namhyung Kim Cc: Perry Taylor Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Richter Cc: Xing Zhengjun Link: https://lore.kernel.org/r/20220831174926.579643-5-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf smt: Compute SMT from topology

2022-10-04T11:55:22Z

The topology records sibling threads. Rather than computing SMT using siblings in sysfs, reuse the values in topology. This only applies when the file smt/active isn't available. Signed-off-by: Ian Rogers Cc: Ahmad Yasin Cc: Alexander Shishkin Cc: Andi Kleen Cc: Caleb Biggers Cc: Florian Fischer Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Kan Liang Cc: Kshipra Bopardikar Cc: Mark Rutland Cc: Miaoqian Lin Cc: Namhyung Kim Cc: Perry Taylor Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Richter Cc: Xing Zhengjun Link: https://lore.kernel.org/r/20220831174926.579643-4-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf smt: Tidy header guard add SPDX

2022-10-04T11:55:20Z

Make the header guard consistent with others. Signed-off-by: Ian Rogers Cc: Alexander Shishkin Cc: Andi Kleen Cc: Caleb Biggers Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Kan Liang Cc: Kshipra Bopardikar Cc: Mark Rutland Cc: Miaoqian Lin Cc: Namhyung Kim Cc: Perry Taylor Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Richter Cc: Xing Zhengjun Cc: florian fischer Link: http://lore.kernel.org/lkml/20220830164846.401143-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Probe non-deprecated sysfs path 1st

2022-01-12T17:43:34Z

Following Documentation/ABI/stable/sysfs-devices-system-cpu the /sys/devices/system/cpu/cpuX/topology/core_cpus is deprecated in favor of thread_siblings, so probe thread_siblings before falling back on core_cpus. Signed-off-by: Ian Rogers Cc: Alexander Shishkin Cc: Andi Kleen Cc: Ingo Molnar Cc: Jiri Olsa Cc: John Garry Cc: Kajol Jain Cc: Kan Liang Cc: Konstantin Khlebnikov Cc: Mark Rutland Cc: Namhyung Kim Cc: Paul Clarke Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lore.kernel.org/r/20211124001231.3277836-4-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Fix SMT fallback with large core counts

2022-01-12T17:43:22Z

strtoull can only read a 64-bit bitmap. On an AMD EPYC core_cpus may look like: 00000000,00000000,00000000,00000001,00000000,00000000,00000000,00000001 and so the sibling wasn't spotted. Fix by writing a simple hweight string parser. Signed-off-by: Ian Rogers Cc: Alexander Shishkin Cc: Andi Kleen Cc: Ingo Molnar Cc: Jiri Olsa Cc: John Garry Cc: Kajol Jain Cc: Kan Liang Cc: Konstantin Khlebnikov Cc: Mark Rutland Cc: Namhyung Kim Cc: Paul Clarke Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lore.kernel.org/r/20211124001231.3277836-3-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Fix SMT detection fast read path

2021-12-07T00:57:53Z

sysfs__read_int() returns 0 on success, and so the fast read path was always failing. Fixes: bb629484d924118e ("perf tools: Simplify checking if SMT is active.") Signed-off-by: Ian Rogers Cc: Alexander Shishkin Cc: Andi Kleen Cc: Jiri Olsa Cc: John Garry Cc: Kajol Jain Cc: Kan Liang Cc: Konstantin Khlebnikov Cc: Mark Rutland Cc: Namhyung Kim Cc: Paul Clarke Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lore.kernel.org/lkml/20211124001231.3277836-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Simplify checking if SMT is active.

2020-05-05T19:35:29Z

SMT now could be disabled via "/sys/devices/system/cpu/smt/control". Status is shown in "/sys/devices/system/cpu/smt/active" simply as "0" / "1". If this knob isn't here then fallback to checking topology as before. Signed-off-by: Konstantin Khlebnikov Cc: Andi Kleen Cc: Dmitry Monakhov Cc: Jiri Olsa Cc: Kan Liang Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/158817741394.748034.9273604089138009552.stgit@buzz Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Fix reading new topology attribute "core_cpus"

2020-05-05T19:35:29Z

Check if access("devices/system/cpu/cpu%d/topology/core_cpus", F_OK) fails, which will happen unless the current directory is "/sys". Simply try to read this file first. Fixes: 0ccdb8407a46 ("perf tools: Apply new CPU topology sysfs attributes") Signed-off-by: Konstantin Khlebnikov Cc: Andi Kleen Cc: Dmitry Monakhov Cc: Jiri Olsa Cc: Kan Liang Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/158817718710.747528.11009278875028211991.stgit@buzz Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Apply new CPU topology sysfs attributes

2019-06-10T19:20:11Z

The existing "thread_siblings" and "thread_siblings_list" attribute will be deprecated. Use the new CPU topology sysfs attributes, "core_cpus" and "core_cpus_list", which are synonymous with the deprecated attributes. Check the new name first. If not available, use the deprecated name to be compatible with old kernel. Signed-off-by: Kan Liang Reviewed-by: Jiri Olsa Cc: Andi Kleen Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1559688644-106558-5-git-send-email-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add utility function to detect SMT status

2017-08-22T15:09:04Z

Add an smt_on() function to return if SMT is enabled or disabled. Used in the next patch. Signed-off-by: Andi Kleen Acked-by: Jiri Olsa Link: http://lkml.kernel.org/r/20170811232634.30465-7-andi@firstfloor.org Signed-off-by: Arnaldo Carvalho de Melo