PROF(3) PROF(3)
NAME
prof - profiling device
SYNOPSIS
bind #P /prof
/prof/ctl
/prof/n/name
/prof/n/path
/prof/n/histogram
/prof/n/pctl
DESCRIPTION
The prof device serves a two-level directory structure. The
first level contains a control file ctl and zero or more
numbered directories each corresponding to a module being
profiled. Inside each of these numbered directories are fur-
ther files which describe the particular module being pro-
filed.
The write-only control file ctl provides the facilities to
profile a module. Messages written to this file initiate and
control the profiling.
module name
Add the module or the module whose path is name to
the list of modules to be profiled.
start Start profiling all modules in the above list or,
if the list is empty, start profiling all modules
loaded by the kernel. The profiling is done by
sampling.
startcp As above but do coverage profiling. All instruc-
tions executed in the wanted modules are counted.
startmp As above but do memory profiling. All heap memory
allocations are associated with a line of limbo
source and all deallocations with the line that
did the allocation.
stop Stop all profiling.
end Stop all profiling and free all memory associated
with the modules being profiled. The profiler
returns to it's initial state with no modules
under profile.
interval i
Change the sampling interval to i ms. The default
Page 1 Plan 9 (printed 12/22/24)
PROF(3) PROF(3)
sampling rate is 100 ms.
The second level directories contain information about each
module under profile.
The read-only file name contains the name of the module in
the form it appears in it's module source file.
The read-only file path contains the path of the dis file
that implements the module.
The write-only control file pctl allows finer control of the
profiling of a module. It is not used at present.
The read-only file histogram contains statistics about the
profiled module. The file contains a list of pairs of inte-
gers seperated by a space. The first number of the pair is a
program counter value representing the address of a dis
instruction. Addresses start from 0 and the list is in order
of increasing address. The second number is the frequency
with which this address was sampled. Each read of this file
returns the next pair in the list. The frequency is guaran-
teed to be non-zero.
When coverage profiling the second number of each pair is
the number of times that dis instruction was executed, when
memory profiling it's the amount of memory in bytes.
SOURCE
/emu/port/devprof.c
BUGS
The device profiles on a global basis and therefore does not
distinguish between multiple profilers running at once.
The coverage profiling can only be done on dis instructions.
The device can do only one of time, coverage or memory pro-
filing at once.
Page 2 Plan 9 (printed 12/22/24)