diff options
| -rw-r--r-- | share/man/man4/hwpmc.4 | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/share/man/man4/hwpmc.4 b/share/man/man4/hwpmc.4 index aaa390931081..6536ea5c1e22 100644 --- a/share/man/man4/hwpmc.4 +++ b/share/man/man4/hwpmc.4 @@ -50,8 +50,7 @@ PMCs are allocated using the request. A successful .Dv PMC_OP_PMCALLOCATE -request will return an integer handle (typically a small integer) to -the requesting process. +request will return an integer handle to the requesting process. Subsequent operations on the allocated PMC use this handle to denote the specific PMC. A process that has successfully allocated a PMC is termed an @@ -77,14 +76,14 @@ sampling: In counting modes, the PMCs count hardware events. These counts are retrievable using the .Dv PMC_OP_PMCREAD -system call on all architectures, though some architectures like the -i386 and amd64 offer faster methods of reading these counts. +system call on all architectures. +Some architectures offer faster methods of reading these counts. .It Em Sampling -In sampling modes, where PMCs are configured to sample the CPU +In sampling modes, the PMCs are configured to sample the CPU instruction pointer after a configurable number of hardware events have been observed. -These instruction pointer samples are directed to a log file for -subsequent analysis. +These instruction pointer samples are usually directed to a log file +for subsequent analysis. .El .Pp These modes of operation are orthogonal; a PMC may be configured to @@ -136,7 +135,7 @@ System-wide statistical sampling can only be enabled by a process with super-user privileges. .El .Pp -Processes are allowed to allocate as many PMCs are the hardware and +Processes are allowed to allocate as many PMCs as the hardware and current operating conditions permit. Processes may mix allocations of system-wide and process-private PMCs. @@ -225,7 +224,7 @@ and .Dv PMC_F_LOG_PROCCSW may be used in combination with modifier .Dv PMC_F_DESCENDANTS -to track the behaviour of complex pipelines of processes. +to track the behavior of complex pipelines of processes. PMCs with modifiers .Dv PMC_F_LOG_PROCEXIT and @@ -410,7 +409,7 @@ before .Nm is loaded. .Sh SECURITY CONSIDERATIONS -PMCs may be used to monitor the actual behaviour of the system on hardware. +PMCs may be used to monitor the actual behavior of the system on hardware. In situations where this constitutes an undesirable information leak, the following options are available: .Bl -enum @@ -456,7 +455,7 @@ has permitted user processes running at a processor CPL of 3 to read the TSC using the RDTSC instruction. The .Nm -driver preserves this semantics. +driver preserves this behavior. .Ss Intel P4/HTT Handling On CPUs with HTT support, Intel P4 PMCs are capable of qualifying only a subset of hardware events on a per-logical CPU basis. |