.\" Copyright (c) 2003-2008 Joseph Koshy.  All rights reserved.
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.\" $FreeBSD$
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.Dd October 4, 2008
.Dt PMC.TSC 3
.Os
.Sh NAME
.Nm pmc.tsc
.Nd measurements using the i386 timestamp counter
.Sh LIBRARY
.Lb libpmc
.Sh SYNOPSIS
.In pmc.h
.Sh DESCRIPTION
In the i386 architecture, the timestamp counter is a monotonically
non-decreasing counter that counts processor cycles.
.Pp
This counter may be selected specifying an event specifier
.Dq Li tsc
to
.Xr pmc_allocate 3 .
The TSC is a read-only counter that may only be allocated in
system-wide counting mode.
The
.Dq Li tsc
event does not support further event qualifiers.
.Pp
Multiple processes are allowed to allocate the TSC.
Once allocated, the TSC may be read using the
.Fn pmc_read
function, or by using the
.Li RDTSC
instruction.
.Ss Event Name Aliases
The alias
.Dq Li cycles
maps to the TSC.
.Sh SEE ALSO
.Xr pmc 3 ,
.Xr pmc.atom 3 ,
.Xr pmc.core 3 ,
.Xr pmc.core2 3 ,
.Xr pmc.iaf 3 ,
.Xr pmc.k7 3 ,
.Xr pmc.k8 3 ,
.Xr pmc.p4 3 ,
.Xr pmc.p5 3 ,
.Xr pmc.p6 3 ,
.Xr pmc.soft 3 ,
.Xr pmclog 3 ,
.Xr hwpmc 4
.Sh HISTORY
The
.Nm pmc
library first appeared in
.Fx 6.0 .
.Sh AUTHORS
The
.Lb libpmc
library was written by
.An Joseph Koshy Aq Mt jkoshy@FreeBSD.org .