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Subject[PATCH 3/3] perf/doc: Update perf_event_attr struct
Date
Update the fields in perf_event_attr as currently seen in
include/uapi/linux/perf_event.h

Remove outdated comments on the config field
The doc has not account for commit a21ca2cac582 ("perf_counter:
Separate out attr->type from attr->config").

Signed-off-by: Tom Huynh <tom.huynh@freescale.com>
---
tools/perf/design.txt | 159 +++++++++++++++++++++++++++++++++++---------------
1 file changed, 113 insertions(+), 46 deletions(-)

diff --git a/tools/perf/design.txt b/tools/perf/design.txt
index a28dca2..96bd261 100644
--- a/tools/perf/design.txt
+++ b/tools/perf/design.txt
@@ -32,60 +32,127 @@ can be used to set the blocking mode, etc.
Multiple counters can be kept open at a time, and the counters
can be poll()ed.

-When creating a new counter fd, 'perf_event_attr' is:
+When creating a new counter fd, 'perf_event_attr' is defined in
+include/linux/uapi/perf_event.h as:

struct perf_event_attr {
- /*
- * The MSB of the config word signifies if the rest contains cpu
- * specific (raw) counter configuration data, if unset, the next
- * 7 bits are an event type and the rest of the bits are the event
- * identifier.
- */
- __u64 config;
-
- __u64 irq_period;
- __u32 record_type;
- __u32 read_format;
-
- __u64 disabled : 1, /* off by default */
- inherit : 1, /* children inherit it */
- pinned : 1, /* must always be on PMU */
- exclusive : 1, /* only group on PMU */
- exclude_user : 1, /* don't count user */
- exclude_kernel : 1, /* ditto kernel */
- exclude_hv : 1, /* ditto hypervisor */
- exclude_idle : 1, /* don't count when idle */
- mmap : 1, /* include mmap data */
- munmap : 1, /* include munmap data */
- comm : 1, /* include comm data */
-
- __reserved_1 : 52;
-
- __u32 extra_config_len;
- __u32 wakeup_events; /* wakeup every n events */
-
- __u64 __reserved_2;
- __u64 __reserved_3;
-};

-The 'config' field specifies what the counter should count. It
-is divided into 3 bit-fields:
+ /*
+ * Major type: hardware/software/tracepoint/etc.
+ */
+ __u32 type;
+
+ /*
+ * Size of the attr structure, for fwd/bwd compat.
+ */
+ __u32 size;
+
+ /*
+ * Type specific configuration information.
+ */
+ __u64 config;
+
+ union {
+ __u64 sample_period;
+ __u64 sample_freq;
+ };
+
+ __u64 sample_type;
+ __u64 read_format;
+
+ __u64 disabled : 1, /* off by default */
+ inherit : 1, /* children inherit it */
+ pinned : 1, /* must always be on PMU */
+ exclusive : 1, /* only group on PMU */
+ exclude_user : 1, /* don't count user */
+ exclude_kernel : 1, /* ditto kernel */
+ exclude_hv : 1, /* ditto hypervisor */
+ exclude_idle : 1, /* don't count when idle */
+ mmap : 1, /* include mmap data */
+ comm : 1, /* include comm data */
+ freq : 1, /* use freq, not period */
+ inherit_stat : 1, /* per task counts */
+ enable_on_exec : 1, /* next exec enables */
+ task : 1, /* trace fork/exit */
+ watermark : 1, /* wakeup_watermark */
+ /*
+ * precise_ip:
+ *
+ * 0 - SAMPLE_IP can have arbitrary skid
+ * 1 - SAMPLE_IP must have constant skid
+ * 2 - SAMPLE_IP requested to have 0 skid
+ * 3 - SAMPLE_IP must have 0 skid
+ *
+ * See also PERF_RECORD_MISC_EXACT_IP
+ */
+ precise_ip : 2, /* skid constraint */
+ mmap_data : 1, /* non-exec mmap data */
+ sample_id_all : 1, /* sample_type all events */
+
+ exclude_host : 1, /* don't count in host */
+ exclude_guest : 1, /* don't count in guest */
+
+ exclude_callchain_kernel : 1, /* exclude kernel callchains */
+ exclude_callchain_user : 1, /* exclude user callchains */
+ mmap2 : 1, /* include mmap with inode data */
+ comm_exec : 1, /* flag comm events that are due to an exec */
+ __reserved_1 : 39;
+
+ union {
+ __u32 wakeup_events; /* wakeup every n events */
+ __u32 wakeup_watermark; /* bytes before wakeup */
+ };
+
+ __u32 bp_type;
+ union {
+ __u64 bp_addr;
+ __u64 config1; /* extension of config */
+ };
+ union {
+ __u64 bp_len;
+ __u64 config2; /* extension of config1 */
+ };
+ __u64 branch_sample_type; /* enum perf_branch_sample_type */
+
+ /*
+ * Defines set of user regs to dump on samples.
+ * See asm/perf_regs.h for details.
+ */
+ __u64 sample_regs_user;
+
+ /*
+ * Defines size of the user stack to dump on samples.
+ */
+ __u32 sample_stack_user;

-raw_type: 1 bit (most significant bit) 0x8000_0000_0000_0000
-type: 7 bits (next most significant) 0x7f00_0000_0000_0000
-event_id: 56 bits (least significant) 0x00ff_ffff_ffff_ffff
+ /* Align to u64. */
+ __u32 __reserved_2;
+ /*
+ * Defines set of regs to dump for each sample
+ * state captured on:
+ * - precise = 0: PMU interrupt
+ * - precise > 0: sampled instruction
+ *
+ * See asm/perf_regs.h for details.
+ */
+ __u64 sample_regs_intr;
+};

-If 'raw_type' is 1, then the counter will count a hardware event
-specified by the remaining 63 bits of event_config. The encoding is
-machine-specific.
+The 'config' field specifies what the counter should count. The counter will
+count a hardware event specified by the 64 bits of event_config. The encoding
+is machine-specific.

-If 'raw_type' is 0, then the 'type' field says what kind of counter
-this is, with the following encoding:
+The 'type' field says what kind of counter this is, with the following encoding:

enum perf_type_id {
- PERF_TYPE_HARDWARE = 0,
- PERF_TYPE_SOFTWARE = 1,
- PERF_TYPE_TRACEPOINT = 2,
+ PERF_TYPE_HARDWARE = 0,
+ PERF_TYPE_SOFTWARE = 1,
+ PERF_TYPE_TRACEPOINT = 2,
+ PERF_TYPE_HW_CACHE = 3,
+ PERF_TYPE_RAW = 4,
+ PERF_TYPE_BREAKPOINT = 5,
+
+ PERF_TYPE_MAX, /* non-ABI */
};

A counter of PERF_TYPE_HARDWARE will count the hardware event
--
1.9.1


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