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authorIngo Molnar <mingo@elte.hu>2009-09-21 06:02:48 -0400
committerIngo Molnar <mingo@elte.hu>2009-09-21 08:28:04 -0400
commitcdd6c482c9ff9c55475ee7392ec8f672eddb7be6 (patch)
tree81f98a3ab46c589792057fe2392c1e10f8ad7893 /tools/perf/design.txt
parentdfc65094d0313cc48969fa60bcf33d693aeb05a7 (diff)
perf: Do the big rename: Performance Counters -> Performance Events
Bye-bye Performance Counters, welcome Performance Events! In the past few months the perfcounters subsystem has grown out its initial role of counting hardware events, and has become (and is becoming) a much broader generic event enumeration, reporting, logging, monitoring, analysis facility. Naming its core object 'perf_counter' and naming the subsystem 'perfcounters' has become more and more of a misnomer. With pending code like hw-breakpoints support the 'counter' name is less and less appropriate. All in one, we've decided to rename the subsystem to 'performance events' and to propagate this rename through all fields, variables and API names. (in an ABI compatible fashion) The word 'event' is also a bit shorter than 'counter' - which makes it slightly more convenient to write/handle as well. Thanks goes to Stephane Eranian who first observed this misnomer and suggested a rename. User-space tooling and ABI compatibility is not affected - this patch should be function-invariant. (Also, defconfigs were not touched to keep the size down.) This patch has been generated via the following script: FILES=$(find * -type f | grep -vE 'oprofile|[^K]config') sed -i \ -e 's/PERF_EVENT_/PERF_RECORD_/g' \ -e 's/PERF_COUNTER/PERF_EVENT/g' \ -e 's/perf_counter/perf_event/g' \ -e 's/nb_counters/nb_events/g' \ -e 's/swcounter/swevent/g' \ -e 's/tpcounter_event/tp_event/g' \ $FILES for N in $(find . -name perf_counter.[ch]); do M=$(echo $N | sed 's/perf_counter/perf_event/g') mv $N $M done FILES=$(find . -name perf_event.*) sed -i \ -e 's/COUNTER_MASK/REG_MASK/g' \ -e 's/COUNTER/EVENT/g' \ -e 's/\<event\>/event_id/g' \ -e 's/counter/event/g' \ -e 's/Counter/Event/g' \ $FILES ... to keep it as correct as possible. This script can also be used by anyone who has pending perfcounters patches - it converts a Linux kernel tree over to the new naming. We tried to time this change to the point in time where the amount of pending patches is the smallest: the end of the merge window. Namespace clashes were fixed up in a preparatory patch - and some stylistic fallout will be fixed up in a subsequent patch. ( NOTE: 'counters' are still the proper terminology when we deal with hardware registers - and these sed scripts are a bit over-eager in renaming them. I've undone some of that, but in case there's something left where 'counter' would be better than 'event' we can undo that on an individual basis instead of touching an otherwise nicely automated patch. ) Suggested-by: Stephane Eranian <eranian@google.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Paul Mackerras <paulus@samba.org> Reviewed-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Howells <dhowells@redhat.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: <linux-arch@vger.kernel.org> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'tools/perf/design.txt')
-rw-r--r--tools/perf/design.txt58
1 files changed, 29 insertions, 29 deletions
diff --git a/tools/perf/design.txt b/tools/perf/design.txt
index f71e0d245cba..f1946d107b10 100644
--- a/tools/perf/design.txt
+++ b/tools/perf/design.txt
@@ -18,10 +18,10 @@ underlying hardware counters.
18Performance counters are accessed via special file descriptors. 18Performance counters are accessed via special file descriptors.
19There's one file descriptor per virtual counter used. 19There's one file descriptor per virtual counter used.
20 20
21The special file descriptor is opened via the perf_counter_open() 21The special file descriptor is opened via the perf_event_open()
22system call: 22system call:
23 23
24 int sys_perf_counter_open(struct perf_counter_hw_event *hw_event_uptr, 24 int sys_perf_event_open(struct perf_event_hw_event *hw_event_uptr,
25 pid_t pid, int cpu, int group_fd, 25 pid_t pid, int cpu, int group_fd,
26 unsigned long flags); 26 unsigned long flags);
27 27
@@ -32,9 +32,9 @@ can be used to set the blocking mode, etc.
32Multiple counters can be kept open at a time, and the counters 32Multiple counters can be kept open at a time, and the counters
33can be poll()ed. 33can be poll()ed.
34 34
35When creating a new counter fd, 'perf_counter_hw_event' is: 35When creating a new counter fd, 'perf_event_hw_event' is:
36 36
37struct perf_counter_hw_event { 37struct perf_event_hw_event {
38 /* 38 /*
39 * The MSB of the config word signifies if the rest contains cpu 39 * The MSB of the config word signifies if the rest contains cpu
40 * specific (raw) counter configuration data, if unset, the next 40 * specific (raw) counter configuration data, if unset, the next
@@ -93,7 +93,7 @@ specified by 'event_id':
93 93
94/* 94/*
95 * Generalized performance counter event types, used by the hw_event.event_id 95 * Generalized performance counter event types, used by the hw_event.event_id
96 * parameter of the sys_perf_counter_open() syscall: 96 * parameter of the sys_perf_event_open() syscall:
97 */ 97 */
98enum hw_event_ids { 98enum hw_event_ids {
99 /* 99 /*
@@ -159,7 +159,7 @@ in size.
159 * reads on the counter should return the indicated quantities, 159 * reads on the counter should return the indicated quantities,
160 * in increasing order of bit value, after the counter value. 160 * in increasing order of bit value, after the counter value.
161 */ 161 */
162enum perf_counter_read_format { 162enum perf_event_read_format {
163 PERF_FORMAT_TOTAL_TIME_ENABLED = 1, 163 PERF_FORMAT_TOTAL_TIME_ENABLED = 1,
164 PERF_FORMAT_TOTAL_TIME_RUNNING = 2, 164 PERF_FORMAT_TOTAL_TIME_RUNNING = 2,
165}; 165};
@@ -178,7 +178,7 @@ interrupt:
178 * Bits that can be set in hw_event.record_type to request information 178 * Bits that can be set in hw_event.record_type to request information
179 * in the overflow packets. 179 * in the overflow packets.
180 */ 180 */
181enum perf_counter_record_format { 181enum perf_event_record_format {
182 PERF_RECORD_IP = 1U << 0, 182 PERF_RECORD_IP = 1U << 0,
183 PERF_RECORD_TID = 1U << 1, 183 PERF_RECORD_TID = 1U << 1,
184 PERF_RECORD_TIME = 1U << 2, 184 PERF_RECORD_TIME = 1U << 2,
@@ -228,7 +228,7 @@ these events are recorded in the ring-buffer (see below).
228The 'comm' bit allows tracking of process comm data on process creation. 228The 'comm' bit allows tracking of process comm data on process creation.
229This too is recorded in the ring-buffer (see below). 229This too is recorded in the ring-buffer (see below).
230 230
231The 'pid' parameter to the perf_counter_open() system call allows the 231The 'pid' parameter to the perf_event_open() system call allows the
232counter to be specific to a task: 232counter to be specific to a task:
233 233
234 pid == 0: if the pid parameter is zero, the counter is attached to the 234 pid == 0: if the pid parameter is zero, the counter is attached to the
@@ -258,7 +258,7 @@ The 'flags' parameter is currently unused and must be zero.
258 258
259The 'group_fd' parameter allows counter "groups" to be set up. A 259The 'group_fd' parameter allows counter "groups" to be set up. A
260counter group has one counter which is the group "leader". The leader 260counter group has one counter which is the group "leader". The leader
261is created first, with group_fd = -1 in the perf_counter_open call 261is created first, with group_fd = -1 in the perf_event_open call
262that creates it. The rest of the group members are created 262that creates it. The rest of the group members are created
263subsequently, with group_fd giving the fd of the group leader. 263subsequently, with group_fd giving the fd of the group leader.
264(A single counter on its own is created with group_fd = -1 and is 264(A single counter on its own is created with group_fd = -1 and is
@@ -277,13 +277,13 @@ tracking are logged into a ring-buffer. This ring-buffer is created and
277accessed through mmap(). 277accessed through mmap().
278 278
279The mmap size should be 1+2^n pages, where the first page is a meta-data page 279The mmap size should be 1+2^n pages, where the first page is a meta-data page
280(struct perf_counter_mmap_page) that contains various bits of information such 280(struct perf_event_mmap_page) that contains various bits of information such
281as where the ring-buffer head is. 281as where the ring-buffer head is.
282 282
283/* 283/*
284 * Structure of the page that can be mapped via mmap 284 * Structure of the page that can be mapped via mmap
285 */ 285 */
286struct perf_counter_mmap_page { 286struct perf_event_mmap_page {
287 __u32 version; /* version number of this structure */ 287 __u32 version; /* version number of this structure */
288 __u32 compat_version; /* lowest version this is compat with */ 288 __u32 compat_version; /* lowest version this is compat with */
289 289
@@ -317,7 +317,7 @@ struct perf_counter_mmap_page {
317 * Control data for the mmap() data buffer. 317 * Control data for the mmap() data buffer.
318 * 318 *
319 * User-space reading this value should issue an rmb(), on SMP capable 319 * User-space reading this value should issue an rmb(), on SMP capable
320 * platforms, after reading this value -- see perf_counter_wakeup(). 320 * platforms, after reading this value -- see perf_event_wakeup().
321 */ 321 */
322 __u32 data_head; /* head in the data section */ 322 __u32 data_head; /* head in the data section */
323}; 323};
@@ -327,9 +327,9 @@ NOTE: the hw-counter userspace bits are arch specific and are currently only
327 327
328The following 2^n pages are the ring-buffer which contains events of the form: 328The following 2^n pages are the ring-buffer which contains events of the form:
329 329
330#define PERF_EVENT_MISC_KERNEL (1 << 0) 330#define PERF_RECORD_MISC_KERNEL (1 << 0)
331#define PERF_EVENT_MISC_USER (1 << 1) 331#define PERF_RECORD_MISC_USER (1 << 1)
332#define PERF_EVENT_MISC_OVERFLOW (1 << 2) 332#define PERF_RECORD_MISC_OVERFLOW (1 << 2)
333 333
334struct perf_event_header { 334struct perf_event_header {
335 __u32 type; 335 __u32 type;
@@ -353,8 +353,8 @@ enum perf_event_type {
353 * char filename[]; 353 * char filename[];
354 * }; 354 * };
355 */ 355 */
356 PERF_EVENT_MMAP = 1, 356 PERF_RECORD_MMAP = 1,
357 PERF_EVENT_MUNMAP = 2, 357 PERF_RECORD_MUNMAP = 2,
358 358
359 /* 359 /*
360 * struct { 360 * struct {
@@ -364,10 +364,10 @@ enum perf_event_type {
364 * char comm[]; 364 * char comm[];
365 * }; 365 * };
366 */ 366 */
367 PERF_EVENT_COMM = 3, 367 PERF_RECORD_COMM = 3,
368 368
369 /* 369 /*
370 * When header.misc & PERF_EVENT_MISC_OVERFLOW the event_type field 370 * When header.misc & PERF_RECORD_MISC_OVERFLOW the event_type field
371 * will be PERF_RECORD_* 371 * will be PERF_RECORD_*
372 * 372 *
373 * struct { 373 * struct {
@@ -397,7 +397,7 @@ Notification of new events is possible through poll()/select()/epoll() and
397fcntl() managing signals. 397fcntl() managing signals.
398 398
399Normally a notification is generated for every page filled, however one can 399Normally a notification is generated for every page filled, however one can
400additionally set perf_counter_hw_event.wakeup_events to generate one every 400additionally set perf_event_hw_event.wakeup_events to generate one every
401so many counter overflow events. 401so many counter overflow events.
402 402
403Future work will include a splice() interface to the ring-buffer. 403Future work will include a splice() interface to the ring-buffer.
@@ -409,11 +409,11 @@ events but does continue to exist and maintain its count value.
409 409
410An individual counter or counter group can be enabled with 410An individual counter or counter group can be enabled with
411 411
412 ioctl(fd, PERF_COUNTER_IOC_ENABLE); 412 ioctl(fd, PERF_EVENT_IOC_ENABLE);
413 413
414or disabled with 414or disabled with
415 415
416 ioctl(fd, PERF_COUNTER_IOC_DISABLE); 416 ioctl(fd, PERF_EVENT_IOC_DISABLE);
417 417
418Enabling or disabling the leader of a group enables or disables the 418Enabling or disabling the leader of a group enables or disables the
419whole group; that is, while the group leader is disabled, none of the 419whole group; that is, while the group leader is disabled, none of the
@@ -424,16 +424,16 @@ other counter.
424 424
425Additionally, non-inherited overflow counters can use 425Additionally, non-inherited overflow counters can use
426 426
427 ioctl(fd, PERF_COUNTER_IOC_REFRESH, nr); 427 ioctl(fd, PERF_EVENT_IOC_REFRESH, nr);
428 428
429to enable a counter for 'nr' events, after which it gets disabled again. 429to enable a counter for 'nr' events, after which it gets disabled again.
430 430
431A process can enable or disable all the counter groups that are 431A process can enable or disable all the counter groups that are
432attached to it, using prctl: 432attached to it, using prctl:
433 433
434 prctl(PR_TASK_PERF_COUNTERS_ENABLE); 434 prctl(PR_TASK_PERF_EVENTS_ENABLE);
435 435
436 prctl(PR_TASK_PERF_COUNTERS_DISABLE); 436 prctl(PR_TASK_PERF_EVENTS_DISABLE);
437 437
438This applies to all counters on the current process, whether created 438This applies to all counters on the current process, whether created
439by this process or by another, and doesn't affect any counters that 439by this process or by another, and doesn't affect any counters that
@@ -447,11 +447,11 @@ Arch requirements
447If your architecture does not have hardware performance metrics, you can 447If your architecture does not have hardware performance metrics, you can
448still use the generic software counters based on hrtimers for sampling. 448still use the generic software counters based on hrtimers for sampling.
449 449
450So to start with, in order to add HAVE_PERF_COUNTERS to your Kconfig, you 450So to start with, in order to add HAVE_PERF_EVENTS to your Kconfig, you
451will need at least this: 451will need at least this:
452 - asm/perf_counter.h - a basic stub will suffice at first 452 - asm/perf_event.h - a basic stub will suffice at first
453 - support for atomic64 types (and associated helper functions) 453 - support for atomic64 types (and associated helper functions)
454 - set_perf_counter_pending() implemented 454 - set_perf_event_pending() implemented
455 455
456If your architecture does have hardware capabilities, you can override the 456If your architecture does have hardware capabilities, you can override the
457weak stub hw_perf_counter_init() to register hardware counters. 457weak stub hw_perf_event_init() to register hardware counters.