(A single event on its own is created with
.IR group_fd " = \-1"
and is considered to be a group with only 1 member.)
-An event group is scheduled onto the CPU as a unit: it will only
-be put onto the CPU if all of the events in the group can be put onto
+An event group is scheduled onto the CPU as a unit: it will
+be put onto the CPU ionly if all of the events in the group can be put onto
the CPU.
This means that the values of the member events can be
meaningfully compared, added, divided (to get ratios), etc., with each
must be passed as the
.I pid
parameter.
-cgroup monitoring is only available
+cgroup monitoring is available only
for system-wide events and may therefore require extra permissions.
.P
The
This counts the number of alignment faults.
These happen when unaligned memory accesses happen; the kernel
can handle these but it reduces performance.
-This only happens on some architectures (never on x86).
+This happens only on some architectures (never on x86).
.TP
.BR PERF_COUNT_SW_EMULATION_FAULTS " (Since Linux 2.6.33)"
This counts the number of emulation faults.
.I inherit
bit specifies that this counter should count events of child
tasks as well as the task specified.
-This only applies to new children, not to any existing children at
+This applies only to new children, not to any existing children at
the time the counter is created (nor to any new children of
existing children).
.I pinned
bit specifies that the counter should always be on the CPU if at all
possible.
-It only applies to hardware counters and only to group leaders.
+It applies only to hardware counters and only to group leaders.
If a pinned counter cannot be put onto the CPU (e.g., because there are
not enough hardware counters or because of a conflict with some other
event), then the counter goes into an 'error' state, where reads
.IR "inherit_stat"
This bit enables saving of event counts on context switch for
inherited tasks.
-This is only meaningful if the
+This is meaningful only if the
.I inherit
field is set.
.TP
Normally these are the same.
If more events are started
than available counter slots on the PMU, then multiplexing
-happens and events only run part of the time.
+happens and events run only part of the time.
In that case the
.I time_enabled
and
Enabling or disabling the leader of a group enables or disables the
entire group; that is, while the group leader is disabled, none of the
counters in the group will count.
-Enabling or disabling a member of a group other than the leader only
-affects that counter; disabling a non-leader
+Enabling or disabling a member of a group other than the leader
+affects only that counter; disabling a non-leader
stops that counter from counting but doesn't affect any other counter.
The ioctl argument is ignored.
.B PERF_EVENT_IOC_RESET
Reset the event count specified by the
file descriptor argumentto zero.
-This only resets the counts; there is no way to reset the
+This resets only the counts; there is no way to reset the
multiplexing
.I time_enabled
or
This applies to all counters on the current process, whether created by
this process or by another, and does not affect any counters that this
process has created on other processes.
-It only enables or disables
+It enables or disables only
the group leaders, not any other members in the groups.
.SS perf_event related configuration files
Files in
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