[RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2 Statistical Profiling Extension
From: Will Deacon <hidden>
Date: 2017-01-13 13:33:16
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On Wed, Jan 11, 2017 at 03:02:39PM -0600, Kim Phillips wrote:
On Wed, 11 Jan 2017 12:37:15 +0000 Will Deacon [off-list ref] wrote:quoted
On Tue, Jan 10, 2017 at 04:04:19PM -0600, Kim Phillips wrote:quoted
Also, curiously, arm_spe_pmu doesn't appear in 'perf list' (even when SPE h/w is present).Weird, it would be nice to understand why that is. The sysfs plumbing should all be there, so I'd expect to see something. On my laptop, for example, intel_pt appears as: intel_pt// [Kernel PMU event] and strace show perf doing the following: stat("/sys/bus/event_source/devices/intel_pt/format", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 open("/sys/bus/event_source/devices/intel_pt/format", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 82 open("/sys/bus/event_source/devices/intel_pt/format/psb_period", O_RDONLY) = 83 open("/sys/bus/event_source/devices/intel_pt/format/noretcomp", O_RDONLY) = 83 open("/sys/bus/event_source/devices/intel_pt/format/tsc", O_RDONLY) = 83 open("/sys/bus/event_source/devices/intel_pt/format/cyc_thresh", O_RDONLY) = 83 open("/sys/bus/event_source/devices/intel_pt/format/mtc_period", O_RDONLY) = 83 open("/sys/bus/event_source/devices/intel_pt/format/cyc", O_RDONLY) = 83 open("/sys/bus/event_source/devices/intel_pt/format/mtc", O_RDONLY) = 83 stat("/sys/bus/event_source/devices/intel_pt/events", 0x7ffe54eebb40) = -1 ENOENT (No such file or directory) stat("/sys/bus/event_source/devices/intel_pt/type", {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0 open("/sys/bus/event_source/devices/intel_pt/type", O_RDONLY) = 82 stat("/sys/bus/event_source/devices/intel_pt/cpumask", 0x7ffe54eedd60) = -1 ENOENT (No such file or directory) stat("/sys/bus/event_source/devices/intel_pt/cpus", 0x7ffe54eedd60) = -1 ENOENT (No such file or directory) stat("/sys/bus/event_source/devices/intel_pt/caps/mtc", {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0 open("/sys/bus/event_source/devices/intel_pt/caps/mtc", O_RDONLY) = 82 stat("/sys/bus/event_source/devices/intel_pt/caps/psb_cyc", {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0 open("/sys/bus/event_source/devices/intel_pt/caps/psb_cyc", O_RDONLY) = 82 What do you see for SPE?2154 newfstatat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format", {st_mode=S_IFDIR|0755, st_size=0, ...}, 0) = 0 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 58 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/branch_filter", O_RDONLY) = 59 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/ts_enable", O_RDONLY) = 59 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/pa_enable", O_RDONLY) = 59 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/event_filter", O_RDONLY) = 59 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/load_filter", O_RDONLY) = 59 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/jitter", O_RDONLY) = 59 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/store_filter", O_RDONLY) = 59 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/format/min_latency", O_RDONLY) = 59 2154 newfstatat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/events", 0xffffcd6bb078, 0) = -1 ENOENT (No such file or directory) 2154 newfstatat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/type", {st_mode=S_IFREG|0444, st_size=4096, ...}, 0) = 0 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/type", O_RDONLY) = 58 2154 newfstatat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/cpumask", {st_mode=S_IFREG|0444, st_size=4096, ...}, 0) = 0 2154 openat(AT_FDCWD, "/sys/bus/event_source/devices/arm_spe_pmu_0/cpumask", O_RDONLY) = 58 they're identical up until /.../cpumask's stat, which exists on the ARM SPE run (as opposed to the Intel run).
From a quick look at the perf tool code, it looks like you need to ensure
that pmu->selectable is set to true for SPE, since it doesn't advertise any events (the intel pt and coresight code does this already). Will