From c1043fcda1b9e8e5144cfdaee7be262c50dbdead Mon Sep 17 00:00:00 2001 From: Hiraku Toyooka Date: Wed, 26 Dec 2012 11:53:09 +0900 Subject: tracing: Add documentation of snapshot utility This patch adds snapshot description in ftrace documentation. This description includes what the snapshot is and how to use it. Link: http://lkml.kernel.org/r/20121226025309.3252.150.stgit@liselsia Cc: Rob Landley Signed-off-by: Hiraku Toyooka Signed-off-by: Steven Rostedt --- Documentation/trace/ftrace.txt | 83 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) (limited to 'Documentation') diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 6f51fed45f2d..53d6a3c51d87 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -1842,6 +1842,89 @@ an error. # cat buffer_size_kb 85 +Snapshot +-------- +CONFIG_TRACER_SNAPSHOT makes a generic snapshot feature +available to all non latency tracers. (Latency tracers which +record max latency, such as "irqsoff" or "wakeup", can't use +this feature, since those are already using the snapshot +mechanism internally.) + +Snapshot preserves a current trace buffer at a particular point +in time without stopping tracing. Ftrace swaps the current +buffer with a spare buffer, and tracing continues in the new +current (=previous spare) buffer. + +The following debugfs files in "tracing" are related to this +feature: + + snapshot: + + This is used to take a snapshot and to read the output + of the snapshot. Echo 1 into this file to allocate a + spare buffer and to take a snapshot (swap), then read + the snapshot from this file in the same format as + "trace" (described above in the section "The File + System"). Both reads snapshot and tracing are executable + in parallel. When the spare buffer is allocated, echoing + 0 frees it, and echoing else (positive) values clear the + snapshot contents. + More details are shown in the table below. + + status\input | 0 | 1 | else | + --------------+------------+------------+------------+ + not allocated |(do nothing)| alloc+swap | EINVAL | + --------------+------------+------------+------------+ + allocated | free | swap | clear | + --------------+------------+------------+------------+ + +Here is an example of using the snapshot feature. + + # echo 1 > events/sched/enable + # echo 1 > snapshot + # cat snapshot +# tracer: nop +# +# entries-in-buffer/entries-written: 71/71 #P:8 +# +# _-----=> irqs-off +# / _----=> need-resched +# | / _---=> hardirq/softirq +# || / _--=> preempt-depth +# ||| / delay +# TASK-PID CPU# |||| TIMESTAMP FUNCTION +# | | | |||| | | + -0 [005] d... 2440.603828: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=snapshot-test-2 next_pid=2242 next_prio=120 + sleep-2242 [005] d... 2440.603846: sched_switch: prev_comm=snapshot-test-2 prev_pid=2242 prev_prio=120 prev_state=R ==> next_comm=kworker/5:1 next_pid=60 next_prio=120 +[...] + -0 [002] d... 2440.707230: sched_switch: prev_comm=swapper/2 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=snapshot-test-2 next_pid=2229 next_prio=120 + + # cat trace +# tracer: nop +# +# entries-in-buffer/entries-written: 77/77 #P:8 +# +# _-----=> irqs-off +# / _----=> need-resched +# | / _---=> hardirq/softirq +# || / _--=> preempt-depth +# ||| / delay +# TASK-PID CPU# |||| TIMESTAMP FUNCTION +# | | | |||| | | + -0 [007] d... 2440.707395: sched_switch: prev_comm=swapper/7 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=snapshot-test-2 next_pid=2243 next_prio=120 + snapshot-test-2-2229 [002] d... 2440.707438: sched_switch: prev_comm=snapshot-test-2 prev_pid=2229 prev_prio=120 prev_state=S ==> next_comm=swapper/2 next_pid=0 next_prio=120 +[...] + + +If you try to use this snapshot feature when current tracer is +one of the latency tracers, you will get the following results. + + # echo wakeup > current_tracer + # echo 1 > snapshot +bash: echo: write error: Device or resource busy + # cat snapshot +cat: snapshot: Device or resource busy + ----------- More details can be found in the source code, in the -- cgit v1.2.3 From 1c53a270724df91276d28d66f8e5a302fc6a5d74 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Tue, 22 Jan 2013 22:24:54 -0800 Subject: perf/POWER7: Make generic event translations available in sysfs Make the generic perf events in POWER7 available via sysfs. $ ls /sys/bus/event_source/devices/cpu/events branch-instructions branch-misses cache-misses cache-references cpu-cycles instructions stalled-cycles-backend stalled-cycles-frontend $ cat /sys/bus/event_source/devices/cpu/events/cache-misses event=0x400f0 This patch is based on commits that implement this functionality on x86. Eg: commit a47473939db20e3961b200eb00acf5fcf084d755 Author: Jiri Olsa Date: Wed Oct 10 14:53:11 2012 +0200 perf/x86: Make hardware event translations available in sysfs Changelog:[v2] [Jiri Osla] Drop EVENT_ID() macro since it is only used once. Signed-off-by: Sukadev Bhattiprolu Cc: Andi Kleen Cc: Anton Blanchard Cc: Ingo Molnar Cc: Jiri Olsa Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Robert Richter Cc: Stephane Eranian Cc: linuxppc-dev@ozlabs.org Link: http://lkml.kernel.org/r/20130123062454.GD13720@us.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- Documentation/ABI/stable/sysfs-devices-cpu-events | 0 arch/powerpc/include/asm/perf_event_server.h | 23 +++++++++++++++ arch/powerpc/perf/core-book3s.c | 12 ++++++++ arch/powerpc/perf/power7-pmu.c | 34 +++++++++++++++++++++++ 4 files changed, 69 insertions(+) create mode 100644 Documentation/ABI/stable/sysfs-devices-cpu-events (limited to 'Documentation') diff --git a/Documentation/ABI/stable/sysfs-devices-cpu-events b/Documentation/ABI/stable/sysfs-devices-cpu-events new file mode 100644 index 000000000000..e69de29bb2d1 diff --git a/arch/powerpc/include/asm/perf_event_server.h b/arch/powerpc/include/asm/perf_event_server.h index 9710be3a2d17..b9b6c557bd0c 100644 --- a/arch/powerpc/include/asm/perf_event_server.h +++ b/arch/powerpc/include/asm/perf_event_server.h @@ -11,6 +11,7 @@ #include #include +#include #define MAX_HWEVENTS 8 #define MAX_EVENT_ALTERNATIVES 8 @@ -35,6 +36,7 @@ struct power_pmu { void (*disable_pmc)(unsigned int pmc, unsigned long mmcr[]); int (*limited_pmc_event)(u64 event_id); u32 flags; + const struct attribute_group **attr_groups; int n_generic; int *generic_events; int (*cache_events)[PERF_COUNT_HW_CACHE_MAX] @@ -109,3 +111,24 @@ extern unsigned long perf_instruction_pointer(struct pt_regs *regs); * If an event_id is not subject to the constraint expressed by a particular * field, then it will have 0 in both the mask and value for that field. */ + +extern ssize_t power_events_sysfs_show(struct device *dev, + struct device_attribute *attr, char *page); + +/* + * EVENT_VAR() is same as PMU_EVENT_VAR with a suffix. + * + * Having a suffix allows us to have aliases in sysfs - eg: the generic + * event 'cpu-cycles' can have two entries in sysfs: 'cpu-cycles' and + * 'PM_CYC' where the latter is the name by which the event is known in + * POWER CPU specification. + */ +#define EVENT_VAR(_id, _suffix) event_attr_##_id##_suffix +#define EVENT_PTR(_id, _suffix) &EVENT_VAR(_id, _suffix) + +#define EVENT_ATTR(_name, _id, _suffix) \ + PMU_EVENT_ATTR(_name, EVENT_VAR(_id, _suffix), PME_PM_##_id, \ + power_events_sysfs_show) + +#define GENERIC_EVENT_ATTR(_name, _id) EVENT_ATTR(_name, _id, _g) +#define GENERIC_EVENT_PTR(_id) EVENT_PTR(_id, _g) diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index aa2465e21f1a..fa476d50791f 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -1305,6 +1305,16 @@ static int power_pmu_event_idx(struct perf_event *event) return event->hw.idx; } +ssize_t power_events_sysfs_show(struct device *dev, + struct device_attribute *attr, char *page) +{ + struct perf_pmu_events_attr *pmu_attr; + + pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr); + + return sprintf(page, "event=0x%02llx\n", pmu_attr->id); +} + struct pmu power_pmu = { .pmu_enable = power_pmu_enable, .pmu_disable = power_pmu_disable, @@ -1537,6 +1547,8 @@ int __cpuinit register_power_pmu(struct power_pmu *pmu) pr_info("%s performance monitor hardware support registered\n", pmu->name); + power_pmu.attr_groups = ppmu->attr_groups; + #ifdef MSR_HV /* * Use FCHV to ignore kernel events if MSR.HV is set. diff --git a/arch/powerpc/perf/power7-pmu.c b/arch/powerpc/perf/power7-pmu.c index eebb36de429f..269bf2464a36 100644 --- a/arch/powerpc/perf/power7-pmu.c +++ b/arch/powerpc/perf/power7-pmu.c @@ -374,6 +374,39 @@ static int power7_cache_events[C(MAX)][C(OP_MAX)][C(RESULT_MAX)] = { }, }; + +GENERIC_EVENT_ATTR(cpu-cycles, CYC); +GENERIC_EVENT_ATTR(stalled-cycles-frontend, GCT_NOSLOT_CYC); +GENERIC_EVENT_ATTR(stalled-cycles-backend, CMPLU_STALL); +GENERIC_EVENT_ATTR(instructions, INST_CMPL); +GENERIC_EVENT_ATTR(cache-references, LD_REF_L1); +GENERIC_EVENT_ATTR(cache-misses, LD_MISS_L1); +GENERIC_EVENT_ATTR(branch-instructions, BRU_FIN); +GENERIC_EVENT_ATTR(branch-misses, BRU_MPRED); + +static struct attribute *power7_events_attr[] = { + GENERIC_EVENT_PTR(CYC), + GENERIC_EVENT_PTR(GCT_NOSLOT_CYC), + GENERIC_EVENT_PTR(CMPLU_STALL), + GENERIC_EVENT_PTR(INST_CMPL), + GENERIC_EVENT_PTR(LD_REF_L1), + GENERIC_EVENT_PTR(LD_MISS_L1), + GENERIC_EVENT_PTR(BRU_FIN), + GENERIC_EVENT_PTR(BRU_MPRED), + NULL +}; + + +static struct attribute_group power7_pmu_events_group = { + .name = "events", + .attrs = power7_events_attr, +}; + +static const struct attribute_group *power7_pmu_attr_groups[] = { + &power7_pmu_events_group, + NULL, +}; + static struct power_pmu power7_pmu = { .name = "POWER7", .n_counter = 6, @@ -385,6 +418,7 @@ static struct power_pmu power7_pmu = { .get_alternatives = power7_get_alternatives, .disable_pmc = power7_disable_pmc, .flags = PPMU_ALT_SIPR, + .attr_groups = power7_pmu_attr_groups, .n_generic = ARRAY_SIZE(power7_generic_events), .generic_events = power7_generic_events, .cache_events = &power7_cache_events, -- cgit v1.2.3 From 2ac3634a7e1c8eedc961030c87c5c36ebd5bbf8e Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Tue, 22 Jan 2013 22:26:45 -0800 Subject: perf: Document the ABI of perf sysfs entries This patchset addes two new sets of files to sysfs for POWER architecture. - perf event config format in /sys/devices/cpu/format/event - generic and POWER-specific perf events in /sys/devices/cpu/events/ The format of the first file is already documented in: sysfs-bus-event_source-devices-format Document the format of the second set of files '/sys/devices/cpu/events/*' which would also become part of the ABI. Changelog[v4]: [Jiri Olsa]: Mention that multiple event= like terms can be specified in the 'events' file. [Jiri Olsa]: Remove the documentation for the 'config format' file as it is already documented in 'Documentation/ABI/testing/'. [Jiri Olsa]: Move ABI documentation from 'stable/' to 'testing/' Changelog[v3]: [Greg KH] Include ABI documentation. Signed-off-by: Sukadev Bhattiprolu Acked-by: Jiri Olsa Cc: Andi Kleen Cc: Anton Blanchard Cc: Ingo Molnar Cc: Jiri Olsa Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Robert Richter Cc: Stephane Eranian Cc: linuxppc-dev@ozlabs.org Link: http://lkml.kernel.org/r/20130123062645.GG13720@us.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- Documentation/ABI/stable/sysfs-devices-cpu-events | 0 .../testing/sysfs-bus-event_source-devices-events | 62 ++++++++++++++++++++++ 2 files changed, 62 insertions(+) delete mode 100644 Documentation/ABI/stable/sysfs-devices-cpu-events create mode 100644 Documentation/ABI/testing/sysfs-bus-event_source-devices-events (limited to 'Documentation') diff --git a/Documentation/ABI/stable/sysfs-devices-cpu-events b/Documentation/ABI/stable/sysfs-devices-cpu-events deleted file mode 100644 index e69de29bb2d1..000000000000 diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-events b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events new file mode 100644 index 000000000000..0adeb524c0d4 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events @@ -0,0 +1,62 @@ +What: /sys/devices/cpu/events/ + /sys/devices/cpu/events/branch-misses + /sys/devices/cpu/events/cache-references + /sys/devices/cpu/events/cache-misses + /sys/devices/cpu/events/stalled-cycles-frontend + /sys/devices/cpu/events/branch-instructions + /sys/devices/cpu/events/stalled-cycles-backend + /sys/devices/cpu/events/instructions + /sys/devices/cpu/events/cpu-cycles + +Date: 2013/01/08 + +Contact: Linux kernel mailing list + +Description: Generic performance monitoring events + + A collection of performance monitoring events that may be + supported by many/most CPUs. These events can be monitored + using the 'perf(1)' tool. + + The contents of each file would look like: + + event=0xNNNN + + where 'N' is a hex digit and the number '0xNNNN' shows the + "raw code" for the perf event identified by the file's + "basename". + + +What: /sys/devices/cpu/events/PM_LD_MISS_L1 + /sys/devices/cpu/events/PM_LD_REF_L1 + /sys/devices/cpu/events/PM_CYC + /sys/devices/cpu/events/PM_BRU_FIN + /sys/devices/cpu/events/PM_GCT_NOSLOT_CYC + /sys/devices/cpu/events/PM_BRU_MPRED + /sys/devices/cpu/events/PM_INST_CMPL + /sys/devices/cpu/events/PM_CMPLU_STALL + +Date: 2013/01/08 + +Contact: Linux kernel mailing list + Linux Powerpc mailing list + +Description: POWER-systems specific performance monitoring events + + A collection of performance monitoring events that may be + supported by the POWER CPU. These events can be monitored + using the 'perf(1)' tool. + + These events may not be supported by other CPUs. + + The contents of each file would look like: + + event=0xNNNN + + where 'N' is a hex digit and the number '0xNNNN' shows the + "raw code" for the perf event identified by the file's + "basename". + + Further, multiple terms like 'event=0xNNNN' can be specified + and separated with comma. All available terms are defined in + the /sys/bus/event_source/devices//format file. -- cgit v1.2.3