9b5e82f535
MFC after: 1 week
748 lines
22 KiB
Groff
748 lines
22 KiB
Groff
.\" Copyright (c) 2003-2005 Joseph Koshy
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd September 28, 2005
|
|
.Dt HWPMC 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm hwpmc
|
|
.Nd "Hardware Performance Monitoring Counter support"
|
|
.Sh SYNOPSIS
|
|
.Cd "options HWPMC_HOOKS"
|
|
.Cd "device hwpmc"
|
|
.Pp
|
|
Additionally, for i386 systems:
|
|
.Cd "device apic"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
driver virtualizes the hardware performance monitoring facilities in
|
|
modern CPUs and provides support for using these facilities from
|
|
user level processes.
|
|
.Pp
|
|
The driver supports multi-processor systems.
|
|
.Pp
|
|
PMCs are allocated using the
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
request.
|
|
A successful
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
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
|
|
.Dq "owner process" .
|
|
.Pp
|
|
PMCs may be allocated to operate in process-private or in system-wide
|
|
modes.
|
|
.Bl -tag -width ".Em Process-private"
|
|
.It Em Process-private
|
|
In process-private mode, a PMC is active only when a thread belonging
|
|
to a process it is attached to is scheduled on a CPU.
|
|
.It Em System-wide
|
|
In system-wide mode, a PMC operates independently of processes and
|
|
measures hardware events for the system as a whole.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Nm
|
|
driver supports the use of hardware PMCs for counting or for
|
|
sampling:
|
|
.Bl -tag -width ".Em Counting"
|
|
.It Em Counting
|
|
In counting modes, the PMCs count hardware events.
|
|
These counts are retrievable using the
|
|
.Dv PMC_OP_PMCREAD
|
|
system call on all architectures.
|
|
Some architectures offer faster methods of reading these counts.
|
|
.It Em Sampling
|
|
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 usually directed to a log file
|
|
for subsequent analysis.
|
|
.El
|
|
.Pp
|
|
These modes of operation are orthogonal; a PMC may be configured to
|
|
operate in one of four modes:
|
|
.Bl -tag -width indent
|
|
.It Process-private, counting
|
|
These PMCs count hardware events whenever a thread in their attached process is
|
|
scheduled on a CPU.
|
|
These PMCs normally count from zero, but the initial count may be
|
|
set using the
|
|
.Dv PMC_OP_SETCOUNT
|
|
operation.
|
|
Applications can read the value of the PMC anytime using the
|
|
.Dv PMC_OP_PMCRW
|
|
operation.
|
|
.It Process-private, sampling
|
|
These PMCs sample the target processes instruction pointer after they
|
|
have seen the configured number of hardware events.
|
|
The PMCs only count events when a thread belonging to their attached
|
|
process is active.
|
|
The desired frequency of sampling is set using the
|
|
.Dv PMC_OP_SETCOUNT
|
|
operation prior to starting the PMC.
|
|
Log files are configured using the
|
|
.Dv PMC_OP_CONFIGURELOG
|
|
operation.
|
|
.It System-wide, counting
|
|
These PMCs count hardware events seen by them independent of the
|
|
processes that are executing.
|
|
The current count on these PMCs can be read using the
|
|
.Dv PMC_OP_PMCRW
|
|
request.
|
|
These PMCs normally count from zero, but the initial count may be
|
|
set using the
|
|
.Dv PMC_OP_SETCOUNT
|
|
operation.
|
|
.It System-wide, sampling
|
|
These PMCs will periodically sample the instruction pointer of the CPU
|
|
they are allocated on, and will write the sample to a log for further
|
|
processing.
|
|
The desired frequency of sampling is set using the
|
|
.Dv PMC_OP_SETCOUNT
|
|
operation prior to starting the PMC.
|
|
Log files are configured using the
|
|
.Dv PMC_OP_CONFIGURELOG
|
|
operation.
|
|
.Pp
|
|
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 as the hardware and
|
|
current operating conditions permit.
|
|
Processes may mix allocations of system-wide and process-private
|
|
PMCs.
|
|
Multiple processes are allowed to be concurrently using the facilities
|
|
of the
|
|
.Nm
|
|
driver.
|
|
.Pp
|
|
Allocated PMCs are started using the
|
|
.Dv PMC_OP_PMCSTART
|
|
operation, and stopped using the
|
|
.Dv PMC_OP_PMCSTOP
|
|
operation.
|
|
Stopping and starting a PMC is permitted at any time the owner process
|
|
has a valid handle to the PMC.
|
|
.Pp
|
|
Process-private PMCs need to be attached to a target process before
|
|
they can be used.
|
|
Attaching a process to a PMC is done using the
|
|
.Dv PMC_OP_PMCATTACH
|
|
operation.
|
|
An already attached PMC may be detached from its target process
|
|
using the converse
|
|
.Dv PMC_OP_PMCDETACH
|
|
operation.
|
|
Issuing a
|
|
.Dv PMC_OP_PMCSTART
|
|
operation on an as yet unattached PMC will cause it to be attached
|
|
to its owner process.
|
|
The following rules determine whether a given process may attach
|
|
a PMC to another target process:
|
|
.Bl -bullet -compact
|
|
.It
|
|
A non-jailed process with super-user privileges is allowed to attach
|
|
to any other process in the system.
|
|
.It
|
|
Other processes are only allowed to attach to targets that they would
|
|
be able to attach to for debugging (as determined by
|
|
.Xr p_candebug 9 ) .
|
|
.El
|
|
.Pp
|
|
PMCs are released using
|
|
.Dv PMC_OP_PMCRELEASE .
|
|
After a successful
|
|
.Dv PMC_OP_PMCRELEASE
|
|
operation the handle to the PMC will become invalid.
|
|
.Ss Modifier Flags
|
|
The
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
operation supports the following flags that modify the behavior
|
|
of an allocated PMC:
|
|
.Bl -tag -width indent
|
|
.It Dv PMC_F_DESCENDANTS
|
|
This modifier is valid only for a PMC being allocated in process-private
|
|
mode.
|
|
It signifies that the PMC will track hardware events for its
|
|
target process and the target's current and future descendants.
|
|
.It Dv PMC_F_KGMON
|
|
This modifier is valid only for a PMC being allocated in system-wide
|
|
sampling mode.
|
|
It signifies that the PMC's sampling interrupt is to be used to drive
|
|
kernel profiling via
|
|
.Xr kgmon 8 .
|
|
.It Dv PMC_F_LOG_PROCCSW
|
|
This modifier is valid only for a PMC being allocated in process-private
|
|
mode.
|
|
When this modifier is present, at every context switch,
|
|
.Nm
|
|
will log a record containing the number of hardware events
|
|
seen by the target process when it was scheduled on the CPU.
|
|
.It Dv PMC_F_LOG_PROCEXIT
|
|
This modifier is valid only for a PMC being allocated in process-private
|
|
mode.
|
|
With this modifier present,
|
|
.Nm
|
|
will maintain per-process counts for each target process attached to
|
|
a PMC.
|
|
At process exit time, a record containing the target process' PID and
|
|
the accumulated per-process count for that process will be written to the
|
|
configured log file.
|
|
.El
|
|
.Pp
|
|
Modifiers
|
|
.Dv PMC_F_LOG_PROCEXIT
|
|
and
|
|
.Dv PMC_F_LOG_PROCCSW
|
|
may be used in combination with modifier
|
|
.Dv PMC_F_DESCENDANTS
|
|
to track the behavior of complex pipelines of processes.
|
|
PMCs with modifiers
|
|
.Dv PMC_F_LOG_PROCEXIT
|
|
and
|
|
.Dv PMC_F_LOG_PROCCSW
|
|
cannot be started until their owner process has configured a log file.
|
|
.Ss Signals
|
|
The
|
|
.Nm
|
|
driver may deliver signals to processes that have allocated PMCs:
|
|
.Bl -tag -width ".Dv SIGBUS"
|
|
.It Dv SIGIO
|
|
A
|
|
.Dv PMC_OP_PMCRW
|
|
operation was attempted on a process-private PMC that does not have
|
|
attached target processes.
|
|
.It Dv SIGBUS
|
|
The
|
|
.Nm
|
|
driver is being unloaded from the kernel.
|
|
.El
|
|
.Sh PROGRAMMING API
|
|
The recommended way for application programs to use the facilities of
|
|
the
|
|
.Nm
|
|
driver is using the API provided by the
|
|
.Xr pmc 3
|
|
library.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
driver operates using a system call number that is dynamically
|
|
allotted to it when it is loaded into the kernel.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
driver supports the following operations:
|
|
.Bl -tag -width indent
|
|
.It Dv PMC_OP_CONFIGURELOG
|
|
Configure a log file for sampling mode PMCs.
|
|
.It Dv PMC_OP_FLUSHLOG
|
|
Transfer buffered log data inside
|
|
.Nm
|
|
to a configured output file.
|
|
This operation returns to the caller after the write operation
|
|
has returned.
|
|
.It Dv PMC_OP_GETCPUINFO
|
|
Retrieve information about the number of CPUs on the system and
|
|
the number of hardware performance monitoring counters available per-CPU.
|
|
.It Dv PMC_OP_GETDRIVERSTATS
|
|
Retrieve module statistics (for analyzing the behavior of
|
|
.Nm
|
|
itself).
|
|
.It Dv PMC_OP_GETMODULEVERSION
|
|
Retrieve the version number of API.
|
|
.It Dv PMC_OP_GETPMCINFO
|
|
Retrieve information about the current state of the PMCs on a
|
|
given CPU.
|
|
.It Dv PMC_OP_PMCADMIN
|
|
Set the administrative state (i.e., whether enabled or disabled) for
|
|
the hardware PMCs managed by the
|
|
.Nm
|
|
driver.
|
|
.It Dv PMC_OP_PMCALLOCATE
|
|
Allocate and configure a PMC.
|
|
On successful allocation, a handle to the PMC (a small integer)
|
|
is returned.
|
|
.It Dv PMC_OP_PMCATTACH
|
|
Attach a process mode PMC to a target process.
|
|
The PMC will be active whenever a thread in the target process is
|
|
scheduled on a CPU.
|
|
.Pp
|
|
If the
|
|
.Dv PMC_F_DESCENDANTS
|
|
flag had been specified at PMC allocation time, then the PMC is
|
|
attached to all current and future descendants of the target process.
|
|
.It Dv PMC_OP_PMCDETACH
|
|
Detach a PMC from its target process.
|
|
.It Dv PMC_OP_PMCRELEASE
|
|
Release a PMC.
|
|
.It Dv PMC_OP_PMCRW
|
|
Read and write a PMC.
|
|
This operation is valid only for PMCs configured in counting modes.
|
|
.It Dv PMC_OP_SETCOUNT
|
|
Set the initial count (for counting mode PMCs) or the desired sampling
|
|
rate (for sampling mode PMCs).
|
|
.It Dv PMC_OP_PMCSTART
|
|
Start a PMC.
|
|
.It Dv PMC_OP_PMCSTOP
|
|
Stop a PMC.
|
|
.It Dv PMC_OP_WRITELOG
|
|
Insert a timestamped user record into the log file.
|
|
.El
|
|
.Ss i386 Specific API
|
|
Some i386 family CPUs support the RDPMC instruction which allows a
|
|
user process to read a PMC value without needing to invoke a
|
|
.Dv PMC_OP_PMCRW
|
|
operation.
|
|
On such CPUs, the machine address associated with an allocated PMC is
|
|
retrievable using the
|
|
.Dv PMC_OP_PMCX86GETMSR
|
|
system call.
|
|
.Bl -tag -width indent
|
|
.It Dv PMC_OP_PMCX86GETMSR
|
|
Retrieve the MSR (machine specific register) number associated with
|
|
the given PMC handle.
|
|
.Pp
|
|
The PMC needs to be in process-private mode and allocated without the
|
|
.Dv PMC_F_DESCENDANTS
|
|
modifier flag, and should be attached only to its owner process at the
|
|
time of the call.
|
|
.El
|
|
.Ss amd64 Specific API
|
|
AMD64 CPUs support the RDPMC instruction which allows a
|
|
user process to read a PMC value without needing to invoke a
|
|
.Dv PMC_OP_PMCRW
|
|
operation.
|
|
The machine address associated with an allocated PMC is
|
|
retrievable using the
|
|
.Dv PMC_OP_PMCX86GETMSR
|
|
system call.
|
|
.Bl -tag -width indent
|
|
.It Dv PMC_OP_PMCX86GETMSR
|
|
Retrieve the MSR (machine specific register) number associated with
|
|
the given PMC handle.
|
|
.Pp
|
|
The PMC needs to be in process-private mode and allocated without the
|
|
.Dv PMC_F_DESCENDANTS
|
|
modifier flag, and should be attached only to its owner process at the
|
|
time of the call.
|
|
.El
|
|
.Sh SYSCTL VARIABLES AND LOADER TUNABLES
|
|
The behavior of
|
|
.Nm
|
|
is influenced by the following
|
|
.Xr sysctl 8
|
|
and
|
|
.Xr loader 8
|
|
tunables:
|
|
.Bl -tag -width indent
|
|
.It Va kern.hwpmc.debugflags Pq string, read-write
|
|
(Only available if the
|
|
.Nm
|
|
driver was compiled with
|
|
.Fl DDEBUG . )
|
|
Control the verbosity of debug messages from the
|
|
.Nm
|
|
driver.
|
|
.It Va kern.hwpmc.hashsize Pq integer, read-only
|
|
The number of rows in the hash tables used to keep track of owner and
|
|
target processes.
|
|
The default is 16.
|
|
.It Va kern.hwpmc.logbuffersize Pq integer, read-only
|
|
The size in kilobytes of each log buffer used by
|
|
.Nm Ns 's
|
|
logging function.
|
|
The default buffer size is 4KB.
|
|
.It Va kern.hwpmc.mtxpoolsize Pq integer, read-only
|
|
The size of the spin mutex pool used by the PMC driver.
|
|
The default is 32.
|
|
.It Va kern.hwpmc.nbuffers Pq integer, read-only
|
|
The number of log buffers used by
|
|
.Nm
|
|
for logging.
|
|
The default is 16.
|
|
.It Va kern.hwpmc.nsamples Pq integer, read-only
|
|
The number of entries in the per-CPU ring buffer used during sampling.
|
|
The default is 16.
|
|
.It Va security.bsd.unprivileged_syspmcs Pq boolean, read-write
|
|
If set to non-zero, allow unprivileged processes to allocate system-wide
|
|
PMCs.
|
|
The default value is 0.
|
|
.It Va security.bsd.unprivileged_proc_debug Pq boolean, read-write
|
|
If set to 0, the
|
|
.Nm
|
|
driver will only allow privileged processes to attach PMCs to other
|
|
processes.
|
|
.El
|
|
.Pp
|
|
These variables may be set in the kernel environment using
|
|
.Xr kenv 1
|
|
before
|
|
.Nm
|
|
is loaded.
|
|
.Sh SECURITY CONSIDERATIONS
|
|
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
|
|
.It
|
|
Set the
|
|
.Xr sysctl 8
|
|
tunable
|
|
.Va security.bsd.unprivileged_syspmcs
|
|
to 0.
|
|
This ensures that unprivileged processes cannot allocate system-wide
|
|
PMCs and thus cannot observe the hardware behavior of the system
|
|
as a whole.
|
|
This tunable may also be set at boot time using
|
|
.Xr loader 8 ,
|
|
or with
|
|
.Xr kenv 1
|
|
prior to loading the
|
|
.Nm
|
|
driver into the kernel.
|
|
.It
|
|
Set the
|
|
.Xr sysctl 8
|
|
tunable
|
|
.Va security.bsd.unprivileged_proc_debug
|
|
to 0.
|
|
This will ensure that an unprivileged process cannot attach a PMC
|
|
to any process other than itself and thus cannot observe the hardware
|
|
behavior of other processes with the same credentials.
|
|
.El
|
|
.Pp
|
|
System administrators should note that on IA-32 platforms
|
|
.Fx
|
|
makes the content of the IA-32 TSC counter available to all processes
|
|
via the RDTSC instruction.
|
|
.Sh IMPLEMENTATION NOTES
|
|
.Ss SMP Symmetry
|
|
The kernel driver requires all physical CPUs in an SMP system to have
|
|
identical performance monitoring counter hardware.
|
|
.Ss x86 TSC Handling
|
|
Historically, on the x86 architecture,
|
|
.Fx
|
|
has permitted user processes running at a processor CPL of 3 to
|
|
read the TSC using the RDTSC instruction.
|
|
The
|
|
.Nm
|
|
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.
|
|
Consequently, if HTT is enabled on a system with Intel Pentium P4
|
|
PMCs, then the
|
|
.Nm
|
|
driver will reject allocation requests for process-private PMCs that
|
|
request counting of hardware events that cannot be counted separately
|
|
for each logical CPU.
|
|
.Ss Intel Pentium-Pro Handling
|
|
Writing a value to the PMC MSRs found in Intel Pentium-Pro style PMCs
|
|
(found in
|
|
.Tn "Intel Pentium Pro" ,
|
|
.Tn "Pentium II" ,
|
|
.Tn "Pentium III" ,
|
|
.Tn "Pentium M"
|
|
and
|
|
.Tn "Celeron"
|
|
processors) will replicate bit 31 of the
|
|
value being written into the upper 8 bits of the MSR,
|
|
bringing down the usable width of these PMCs to 31 bits.
|
|
For process-virtual PMCs, the
|
|
.Nm
|
|
driver implements a workaround in software and makes the corrected 64
|
|
bit count available via the
|
|
.Dv PMC_OP_RW
|
|
operation.
|
|
Processes that intend to use RDPMC instructions directly or
|
|
that intend to write values larger than 2^31 into these PMCs with
|
|
.Dv PMC_OP_RW
|
|
need to be aware of this hardware limitation.
|
|
.Sh DIAGNOSTICS
|
|
.Bl -diag
|
|
.It "hwpmc: [class/npmc/capabilities]..."
|
|
Announce the presence of
|
|
.Va npmc
|
|
PMCs of class
|
|
.Va class ,
|
|
with capabilities described by bit string
|
|
.Va capabilities .
|
|
.It "hwpmc: kernel version (0x%x) does not match module version (0x%x)."
|
|
The module loading process failed because a version mismatch was detected
|
|
between the currently executing kernel and the module being loaded.
|
|
.It "hwpmc: this kernel has not been compiled with 'options HWPMC_HOOKS'."
|
|
The module loading process failed because the currently executing kernel
|
|
was not configured with the required configuration option
|
|
.Dv HWPMC_HOOKS .
|
|
.It "hwpmc: tunable hashsize=%d must be greater than zero."
|
|
A negative value was supplied for tunable
|
|
.Va kern.hwpmc.hashsize .
|
|
.It "hwpmc: tunable logbuffersize=%d must be greater than zero."
|
|
A negative value was supplied for tunable
|
|
.Va kern.hwpmc.logbuffersize .
|
|
.It "hwpmc: tunable nlogbuffers=%d must be greater than zero."
|
|
A negative value was supplied for tunable
|
|
.Va kern.hwpmc.nlogbuffers .
|
|
.It "hwpmc: tunable nsamples=%d out of range."
|
|
The value for tunable
|
|
.Va kern.hwpmc.nsamples
|
|
was negative or greater than 65535.
|
|
.El
|
|
.Sh COMPATIBILITY
|
|
The
|
|
.Nm
|
|
driver is
|
|
.Ud
|
|
The API and ABI documented in this manual page may change in
|
|
the future.
|
|
The recommended method of accessing this driver is using the
|
|
.Xr pmc 3
|
|
API.
|
|
.Sh ERRORS
|
|
A command issued to the
|
|
.Nm
|
|
driver may fail with the following errors:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBUSY
|
|
A
|
|
.Dv PMC_OP_CONFIGURELOG
|
|
operation was requested while an existing log was active.
|
|
.It Bq Er EBUSY
|
|
A DISABLE operation was requested using the
|
|
.Dv PMC_OP_PMCADMIN
|
|
request for a set of hardware resources currently in use for
|
|
process-private PMCs.
|
|
.It Bq Er EBUSY
|
|
A
|
|
.Dv PMC_OP_PMCADMIN
|
|
operation was requested on an active system mode PMC.
|
|
.It Bq Er EBUSY
|
|
A
|
|
.Dv PMC_OP_PMCATTACH
|
|
operation was requested for a target process that already had another
|
|
PMC using the same hardware resources attached to it.
|
|
.It Bq Er EBUSY
|
|
A
|
|
.Dv PMC_OP_PMCRW
|
|
request writing a new value was issued on a PMC that was active.
|
|
.It Bq Er EBUSY
|
|
A
|
|
.Dv PMC_OP_PMCSETCOUNT
|
|
request was issued on a PMC that was active.
|
|
.It Bq Er EDOOFUS
|
|
A
|
|
.Dv PMC_OP_PMCSTART
|
|
operation was requested without a log file being configured for a
|
|
PMC allocated with
|
|
.Dv PMC_F_LOG_PROCCSW
|
|
and
|
|
.Dv PMC_F_LOG_PROCEXIT
|
|
modifiers.
|
|
.It Bq Er EEXIST
|
|
A
|
|
.Dv PMC_OP_PMCATTACH
|
|
request was reissued for a target process that already is the target
|
|
of this PMC.
|
|
.It Bq Er EFAULT
|
|
A bad address was passed in to the driver.
|
|
.It Bq Er EINVAL
|
|
A process specified an invalid PMC handle.
|
|
.It Bq Er EINVAL
|
|
An invalid CPU number was passed in for a
|
|
.Dv PMC_OP_GETPMCINFO
|
|
operation.
|
|
.It Bq Er EINVAL
|
|
An invalid CPU number was passed in for a
|
|
.Dv PMC_OP_PMCADMIN
|
|
operation.
|
|
.It Bq Er EINVAL
|
|
An invalid operation request was passed in for a
|
|
.Dv PMC_OP_PMCADMIN
|
|
operation.
|
|
.It Bq Er EINVAL
|
|
An invalid PMC ID was passed in for a
|
|
.Dv PMC_OP_PMCADMIN
|
|
operation.
|
|
.It Bq Er EINVAL
|
|
A suitable PMC matching the parameters passed in to a
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
request could not be allocated.
|
|
.It Bq Er EINVAL
|
|
An invalid PMC mode was requested during a
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
request.
|
|
.It Bq Er EINVAL
|
|
An invalid CPU number was specified during a
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
request.
|
|
.It Bq Er EINVAL
|
|
A CPU other than
|
|
.Dv PMC_CPU_ANY
|
|
was specified in a
|
|
.Dv PMC_OP_ALLOCATE
|
|
request for a process-private PMC.
|
|
.It Bq Er EINVAL
|
|
A CPU number of
|
|
.Dv PMC_CPU_ANY
|
|
was specified in a
|
|
.Dv PMC_OP_ALLOCATE
|
|
request for a system-wide PMC.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Ar pm_flags
|
|
argument to an
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
request contained unknown flags.
|
|
.It Bq Er EINVAL
|
|
A PMC allocated for system-wide operation was specified with a
|
|
.Dv PMC_OP_PMCATTACH
|
|
request.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Ar pm_pid
|
|
argument to a
|
|
.Dv PMC_OP_PMCATTACH
|
|
request specified an illegal process ID.
|
|
.It Bq Er EINVAL
|
|
A
|
|
.Dv PMC_OP_PMCDETACH
|
|
request was issued for a PMC not attached to the target process.
|
|
.It Bq Er EINVAL
|
|
Argument
|
|
.Ar pm_flags
|
|
to a
|
|
.Dv PMC_OP_PMCRW
|
|
request contained illegal flags.
|
|
.It Bq Er EINVAL
|
|
A
|
|
.Dv PMC_OP_PMCX86GETMSR
|
|
operation was requested for a PMC not in process-virtual mode, or
|
|
for a PMC that is not solely attached to its owner process, or for
|
|
a PMC that was allocated with flag
|
|
.Dv PMC_F_DESCENDANTS .
|
|
.It Bq Er EINVAL
|
|
(On Intel Pentium 4 CPUs with HTT support)
|
|
An allocation request for
|
|
a process-private PMC was issued for an event that does not support
|
|
counting on a per-logical CPU basis.
|
|
.It Bq Er ENOMEM
|
|
The system was not able to allocate kernel memory.
|
|
.It Bq Er ENOSYS
|
|
(i386 architectures)
|
|
A
|
|
.Dv PMC_OP_PMCX86GETMSR
|
|
operation was requested for hardware that does not support reading
|
|
PMCs directly with the RDPMC instruction.
|
|
.It Bq Er ENXIO
|
|
A
|
|
.Dv PMC_OP_GETPMCINFO
|
|
operation was requested for a disabled CPU.
|
|
.It Bq Er ENXIO
|
|
A system-wide PMC on a disabled CPU was requested to be allocated with
|
|
.Dv PMC_OP_PMCALLOCATE .
|
|
.It Bq Er ENXIO
|
|
A
|
|
.Dv PMC_OP_PMCSTART
|
|
or
|
|
.Dv PMC_OP_PMCSTOP
|
|
request was issued for a system-wide PMC that was allocated on a
|
|
currently disabled CPU.
|
|
.It Bq Er EOPNOTSUPP
|
|
A
|
|
.Dv PMC_OP_PMCALLOCATE
|
|
request was issued for PMC capabilities not supported
|
|
by the specified PMC class.
|
|
.It Bq Er EOPNOTSUPP
|
|
(i386 architectures)
|
|
A sampling mode PMC was requested on a CPU lacking an APIC.
|
|
.It Bq Er EPERM
|
|
A
|
|
.Dv PMC_OP_PMCADMIN
|
|
request was issued by a process without super-user
|
|
privilege or by a jailed super-user process.
|
|
.It Bq Er EPERM
|
|
A
|
|
.Dv PMC_OP_PMCATTACH
|
|
operation was issued for a target process that the current process
|
|
does not have permission to attach to.
|
|
.It Bq Er EPERM
|
|
(i386 and amd64 architectures)
|
|
A
|
|
.Dv PMC_OP_PMCATTACH
|
|
operation was issued on a PMC whose MSR has been retrieved using
|
|
.Dv PMC_OP_PMCX86GETMSR .
|
|
.It Bq Er ESRCH
|
|
A process issued a PMC operation request without having allocated any
|
|
PMCs.
|
|
.It Bq Er ESRCH
|
|
A process issued a PMC operation request after the PMC was detached
|
|
from all of its target processes.
|
|
.It Bq Er ESRCH
|
|
A
|
|
.Dv PMC_OP_PMCATTACH
|
|
request specified a non-existent process ID.
|
|
.It Bq Er ESRCH
|
|
The target process for a
|
|
.Dv PMC_OP_PMCDETACH
|
|
operation is not being monitored by the
|
|
.Nm
|
|
driver.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr kenv 1 ,
|
|
.Xr pmc 3 ,
|
|
.Xr pmclog 3 ,
|
|
.Xr kgmon 8 ,
|
|
.Xr kldload 8 ,
|
|
.Xr pmccontrol 8 ,
|
|
.Xr pmcstat 8 ,
|
|
.Xr sysctl 8 ,
|
|
.Xr p_candebug 9
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
driver first appeared in
|
|
.Fx 6.0 .
|
|
.Sh BUGS
|
|
The driver samples the state of the kernel's logical processor support
|
|
at the time of initialization (i.e., at module load time).
|
|
On CPUs supporting logical processors, the driver could misbehave if
|
|
logical processors are subsequently enabled or disabled while the
|
|
driver is active.
|
|
.Pp
|
|
On the i386 architecture, the driver requires that the local APIC on the
|
|
CPU be enabled for sampling mode to be supported.
|
|
Many single-processor motherboards keep the APIC disabled in BIOS; on
|
|
such systems
|
|
.Nm
|
|
will not support sampling PMCs.
|