2007-11-25 06:38:55 +00:00
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.\" Copyright (c) 2007 Joseph Koshy. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" This software is provided by Joseph Koshy ``as is'' and
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.\" any express or implied warranties, including, but not limited to, the
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.\" implied warranties of merchantability and fitness for a particular purpose
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.\" are disclaimed. in no event shall Joseph Koshy be liable
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.\" for any direct, indirect, incidental, special, exemplary, or consequential
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.\" damages (including, but not limited to, procurement of substitute goods
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.\" or services; loss of use, data, or profits; or business interruption)
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.\" however caused and on any theory of liability, whether in contract, strict
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.\" liability, or tort (including negligence or otherwise) arising in any way
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.\" out of the use of this software, even if advised of the possibility of
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.\" such damage.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 25, 2007
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.Dt PMC_READ 3
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2010-04-14 19:08:06 +00:00
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.Os
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2007-11-25 06:38:55 +00:00
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.Sh NAME
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.Nm pmc_read ,
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.Nm pmc_rw ,
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.Nm pmc_write ,
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2009-08-23 06:22:31 +00:00
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.Nd read and write hardware performance counters
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2007-11-25 06:38:55 +00:00
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.Sh LIBRARY
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.Lb libpmc
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.Sh SYNOPSIS
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.In pmc.h
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.Ft int
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.Fn pmc_read "pmc_id_t pmc" "pmc_value_t *value"
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.Ft int
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.Fn pmc_rw "pmc_id_t pmc" "pmc_value_t newvalue" "pmc_value_t *oldvaluep"
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.Ft int
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.Fn pmc_write "pmc_id_t pmc" "pmc_value_t value"
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.Sh DESCRIPTION
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These functions read and write the current value of a PMC.
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.Pp
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Function
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.Fn pmc_read
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with read the current value of the PMC specified by argument
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.Fa pmc
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and write it to the location specified by argument
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.Fa value .
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.Pp
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Function
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.Fn pmc_write
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will set the current value of the PMC specified by argument
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.Fa pmc
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to the value specified by argument
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.Fa value .
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.Pp
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Function
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.Fn pmc_rw
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combines a read and a write into a single atomic operation.
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.Pp
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2009-08-23 06:22:31 +00:00
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For write operations the PMC should be a quiescent state.
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2007-11-25 06:38:55 +00:00
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.Sh RETURN VALUES
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.Rv -std
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.Sh ERRORS
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A call to these functions may fail with the following errors:
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.Bl -tag -width Er
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.It Bq Er EBUSY
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A write operation specified a currently running PMC.
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.It Bq Er EINVAL
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Argument
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.Fa pmc
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specified a PMC not in a readable state.
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.It Bq Er EINVAL
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The PMC specified by argument
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.Fa pmc
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was not owned by the current process.
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.El
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.Sh SEE ALSO
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.Xr pmc 3 ,
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.Xr hwpmc 4
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