\subsection{Performance Monitor}
This object implements a performance monitor for SICS. Please note that SICS
performance is determined not only by processor speed but by a whole range
of factors:
\begin{itemize}
\item Processor speed and memory.
\item Speed of network connctions to hardware devices.
\item Number of clients connected.
\end{itemize}

 The PerfMonTask is called from the SICS task modules main loop. It will then 
 increment a  cycle counter and check if a predefined intergration time has 
 passed. If so a new 
value for cycle  per seconds will be calculated. This is also the main
output of PerfMon. PerfMon implements a callback interface in order to allow
automatical notification about system performance.

PerfMon has a little datastructure:
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$\langle$pdata {\footnotesize ?}$\rangle\equiv$
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\mbox{}\verb@@\\
\mbox{}\verb@    typedef struct __PerfMon {@\\
\mbox{}\verb@                                pObjectDescriptor pDes;@\\
\mbox{}\verb@                                pICallBack        pCall;@\\
\mbox{}\verb@                                int               iLog; /* flag for@\\
\mbox{}\verb@                                                  serverlog writing */       @\\
\mbox{}\verb@                                float fCPS; /* cycles per seconds */@\\
\mbox{}\verb@                                int iInteg; /* integration time */@\\
\mbox{}\verb@                                int iCount;@\\
\mbox{}\verb@                                time_t tLast; /* last time calculated */@\\
\mbox{}\verb@                                time_t tTarget; /* next target time */@\\
\mbox{}\verb@                                int iEnd;@\\
\mbox{}\verb@                             }PerfMon;@\\
\mbox{}\verb@@$\diamond$
\end{list}
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The interface consists of the following functions:
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\mbox{}\verb@  typedef struct __PerfMon *pPerfMon;@\\
\mbox{}\verb@/*---------------------- live and death ----------------------------------*/@\\
\mbox{}\verb@  pPerfMon CreatePerfMon(int iInteg);@\\
\mbox{}\verb@  void     DeletePerfMon(void *pData);@\\
\mbox{}\verb@/*---------------------- increment ---------------------------------------*/@\\
\mbox{}\verb@  int IncrementPerfMon(pPerfMon self);@\\
\mbox{}\verb@/*------------------------------------------------------------------------*/@\\
\mbox{}\verb@  float GetPerformance(pPerfMon self);@\\
\mbox{}\verb@/*------------------------------------------------------------------------*/@\\
\mbox{}\verb@  int PerfMonWrapper(SConnection *pCon, SicsInterp *pSics, void *pData,@\\
\mbox{}\verb@                     int argc, char *argv[]);@\\
\mbox{}\verb@/*-----------------------------------------------------------------------*/@\\
\mbox{}\verb@  int PerfMonTask(void *pPerf);@\\
\mbox{}\verb@  void PerfMonSignal(void *pPerf, int iSignal, void *pSigData);   @\\
\mbox{}\verb@@$\diamond$
\end{list}
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There is really not much to this.

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\mbox{}\verb@/*-------------------------------------------------------------------------@\\
\mbox{}\verb@                            P E R F M O N@\\
\mbox{}\verb@  A performance monitor for SICS. Maintains and calculates a value for@\\
\mbox{}\verb@  cycles per seconds. @\\
\mbox{}\verb@@\\
\mbox{}\verb@  Mark Koennecke, Juli 1997@\\
\mbox{}\verb@@\\
\mbox{}\verb@  copyright: see implementation file@\\
\mbox{}\verb@---------------------------------------------------------------------------*/@\\
\mbox{}\verb@#ifndef SICSPERFMON@\\
\mbox{}\verb@#define SICSPERFMON@\\
\mbox{}\verb@@\\
\mbox{}\verb@@$\langle$pInter {\footnotesize ?}$\rangle$\verb@@\\
\mbox{}\verb@#endif@\\
\mbox{}\verb@@$\diamond$
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\begin{list}{}{} \item
\mbox{}\verb@@\\
\mbox{}\verb@/*--------------------------------------------------------------------------@\\
\mbox{}\verb@   The             P E R F M O N           datastructure.@\\
\mbox{}\verb@@\\
\mbox{}\verb@   Mark Koennecke, Juli 1997@\\
\mbox{}\verb@---------------------------------------------------------------------------*/@\\
\mbox{}\verb@@$\langle$pdata {\footnotesize ?}$\rangle$\verb@@\\
\mbox{}\verb@@$\diamond$
\end{list}
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