mech_g1.modspec

目前最精确的磁盘模拟器的第3版

# diskmodel (version 1.0)
# Authors: John Bucy, Greg Ganger
# Contributors: John Griffin, Jiri Schindler, Steve Schlosser
#
# Copyright (c) of Carnegie Mellon University, 2001, 2002, 2003.
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MODULE mech_g1
PROTO struct dm_mech_if *dm_mech_g1_loadparams(struct lp_block *b, int *num);


PARAM Access time type			S	1 
INIT if(!strcmp(s, "constant")) { } 
INIT else if(!strcmp(s, "averageRotation")) { 
INIT   result->acctime = AVGROTATE; 
INIT } 
INIT else if(!strcmp(s, "trackSwitchPlusRotation")) { 
INIT   result->acctime = SKEWED_FOR_TRACK_SWITCH; 
INIT } 
INIT else { 
INIT   fprintf(stderr, "*** error: Unknown access time type: %s\n", s); 
INIT   return 0; 
INIT }

This specifies the method for computing mechanical delays.  Legal values
are \texttt{constant} which indicates a fixed per-request access time
(i.e.,~actual mechanical activity is not modeled),
\texttt{averageRotation} which indicates that seek activity should be
modeled but rotational latency is assumed to be equal to one half of
a rotation (the statistical mean for random disk access) and
\texttt{trackSwitchPlusRotation} which indicates that both seek and
rotational activity should be modeled.


PARAM Constant access time		D	0 
TEST d >= 0.0
INIT result->acctime = d;

Provides the constant access time to be used if the access time type
is set to constant.


PARAM Seek type				S	1 
INIT if(!strcmp(s, "constant")) {
INIT   result->seektime = SEEK_CONST;
INIT }
INIT else if(!strcmp(s, "linear")) {
INIT   result->seektime = SEEK_3PT_LINE;
INIT }
INIT else if(!strcmp(s, "curve")) { 
INIT   result->seektime = SEEK_3PT_CURVE;
INIT }
INIT else if(!strcmp(s, "hpl")) {
INIT   result->seektime = SEEK_HPL;
INIT }
INIT else if(!strcmp(s, "hplplus10")) {
INIT   result->seektime = SEEK_1ST10_PLUS_HPL;
INIT }
INIT else if(!strcmp(s, "extracted")) {
INIT   result->seektime = SEEK_EXTRACTED;
INIT }
INIT else {
INIT   fprintf(stderr, "*** error: Unknown seek type: %s\n", s);
INIT   return 0;
INIT }
INIT result->seekfn   = dm_mech_g1_seekfns[result->seektime];


This specifies the method for computing seek delays.  
Legal values are the following:

\texttt{linear} indicates that the single-cylinder seek time, the average
seek time, and the full-strobe seek time parameters should be used to
compute the seek time via linear interpolation.

\texttt{curve} indicates that the same three parameters should be used
with the seek equation described in \cite{Lee93} (see Section
\ref{seek.lee}).


\texttt{constant} indicates a fixed per-request seek time.  The
\texttt{Constant seek time} parameter must be provided.

\texttt{hpl} indicates that the six-value \texttt{HPL seek equation values}
parameter (see below) should be used with the seek equation described
in \cite{Ruemmler94} (see below).

\texttt{hplplus10} indicates that the six-value \texttt{HPL seek
equation values} parameter (see below) should be used with the seek
equation described in \cite{Ruemmler94} for all seeks greater than
10~cylinders in length.  For smaller seeks, use the 10-value
\texttt{First ten seek times} parameter (see below) as in
\cite{Worthington94}.

\texttt{extracted} indicates that a more complete seek curve (provided
in a separate file) should be used, with linear interpolation used to
compute the seek time for unspecified distances.  If
\texttt{extracted} layout is used, the parameter \texttt{Full seek curve}
(below) must be provided.


PARAM Average seek time			D	0 
TEST d >= 0.0
INIT result->seekavg = d;

The mean time necessary to perform a random seek

PARAM Constant seek time		D	0 
TEST d >= 0.0
INIT result->seektime = d;

For the ``constant'' seek type (above).

PARAM Single cylinder seek time		D	0 
TEST d >= 0.0
INIT result->seekone = d;

This specifies the time necessary to seek to an adjacent cylinder.


PARAM Full strobe seek time		D	0 
TEST d >= 0.0
INIT result->seekfull = d;

This specifies the full-strobe seek time (i.e.,~the time to seek from the
innermost cylinder to the outermost cylinder).

# filename for now (dm_mech_g1_read_extracted_seek_curve()) 
# eventually list of (distance : I, time : D) pairs 

PARAM Full seek curve			S	0 
DEPEND Seek type
INIT result->seektime = SEEK_EXTRACTED;
INIT dm_mech_g1_read_extracted_seek_curve(s, 
INIT				    &result->xseekcnt, 
INIT			            &result->xseekdists,  
INIT				    &result->xseektimes); 
INIT

The name of the input file containing the seek curve data.
The format of this file is described below.


PARAM Add. write settling delay		D	1 
INIT result->seekwritedelta = dm_time_dtoi(d);

This specifies the additional time required to precisely settle the
read/write head for writing (after a seek or head switch).  As this
parameter implies, the seek times computed using the above parameter
values are for read access.

PARAM Head switch time			D	1 
TEST d >= 0.0 
INIT result->headswitch = dm_time_dtoi(d);

This specifies the time required for a head switch (i.e.,~activating a
different read/write head in order to access a different media
surface).

PARAM Rotation speed (in rpms)		I	1 
TEST i > 0
INIT result->rpm = i;
This specifies the rotation speed of the disk platters in rpms.

PARAM Percent error in rpms		D	1 
TEST RANGE(d, 0.0, 100.0)
INIT result->rpmerr = d;

This specifies the maximum deviation in the rotation speed specified
above.  During initialization, the rotation speed for each
disk is randomly chosen from a uniform distribution of the specified
rotation speed $\pm$ the maximum allowed error.  

%(as computed from this parameter's value).

This feature may be deprecated and should be avoided.


PARAM First ten seek times		LIST	0 
DEPEND Seek type
TEST !do_1st10_seeks(result,l)

This is a list of ten floating-point numbers specifying the seek time for seek
distances of 1~through 10~cylinders.

PARAM HPL seek equation values		LIST	0  
DEPEND Seek type
TEST !do_hpl_seek(result,l)

This is a list containing six numbers specifying the variables 
$V_1$ through $V_6$ of the seek equation described in \cite{Ruemmler94}
(see below).