freebsd-dev/lib/libpmc/pmc_configure_logfile.3
Fabien Thomas dceed24a7c Add a flush of the current PMC log buffer before displaying the next top.
As the underlying block is 4KB if the PMC throughput is low the measurement
will be reported on the next tick. pmcstat(8) use the modified flush API to
reclaim current buffer before displaying next top.

MFC after:	1 month
2011-10-18 15:25:43 +00:00

134 lines
3.5 KiB
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.\" Copyright (c) 2007 Joseph Koshy. All rights reserved.
.\"
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" This software is provided by Joseph Koshy ``as is'' and
.\" any express or implied warranties, including, but not limited to, the
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.\" damages (including, but not limited to, procurement of substitute goods
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.\" $FreeBSD$
.\"
.Dd November 24, 2007
.Dt PMC_CONFIGURE_LOGFILE 3
.Os
.Sh NAME
.Nm pmc_configure_logfile ,
.Nm pmc_flush_logfile ,
.Nm pmc_writelog ,
.Nm pmc_close_logfile
.Nd log file management
.Sh LIBRARY
.Lb libpmc
.Sh SYNOPSIS
.In pmc.h
.Ft int
.Fn pmc_configure_logfile "int fd"
.Ft int
.Fn pmc_flush_logfile void
.Ft int
.Fn pmc_writelog "uint32_t userdata"
.Ft int
.Fn pmc_close_logfile void
.Sh DESCRIPTION
The functions manage logging of
.Xr hwpmc 4
events.
.Pp
Function
.Fn pmc_configure_logfile
is used to turn on and turn off logging.
If argument
.Fa fd
is a valid file handle returned by a prior call to
.Xr open 2
or
.Xr socket 2
then performance events will be logged to the file corresponding
to the specified handle.
If the value of argument
.Fa fd
is -1 then logging will be stopped after any pending data is flushed.
.Pp
Function
.Fn pmc_flush_logfile
will force all log data queued inside the
.Xr hwpmc 4
driver to be written out.
.Pp
Function
.Fn pmc_writelog
will append a log entry containing the value of argument
.Fa userdata
to the log file.
.Pp
Function
.Fn pmc_close_logfile
will flush all pending log data and close
.Xr hwpmc 4 Ns Ap s
side of the stream.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
A call to
.Fn pmc_configure_logfile
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EAGAIN
The
.Xr hwpmc 4
driver was not able to create a helper process due to system limits
being reached.
.It Bq Er EBUSY
Function
.Fn pmc_configure_logfile
was called with a log file already configured.
.It Bq Er EINVAL
Function
.Fn pmc_configure_logfile
was called with an argument of -1 without a log file being previously
configured.
.It Bq Er ENOMEM
The system encountered a memory shortage when servicing this request.
.El
.Pp
A call to
.Fn pmc_flush_logfile
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
Function
.Fn pmc_flush_logfile
was called without a log file being previously configured.
.El
.Pp
A call to
.Fn pmc_writelog
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
Function
.Fn pmc_writelog
was called without a log file being previously configured.
.It Bq Er ENOMEM
The system encountered a memory shortage when servicing this
request.
.El
.Sh SEE ALSO
.Xr pmc 3 ,
.Xr hwpmc 4