cachedev.modspec

目前最精确的磁盘模拟器的第3版

# DiskSim Storage Subsystem Simulation Environment (Version 3.0)
# Revision Authors: John Bucy, Greg Ganger
# Contributors: John Griffin, Jiri Schindler, Steve Schlosser
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MODULE cachedev
PROTO struct cache_def *disksim_cachedev_loadparams(struct lp_block *b);

PARAM Cache size		I	1 
TEST i >= 0
INIT if(result->validmap || result->dirtymap) { fprintf(stderr, "*** ignoring repeat cache size definition.\n"); } else { result->size = i; result->validmap = (bitstr_t *) DISKSIM_malloc(bitstr_size(result->size)); result->dirtymap = (bitstr_t *) DISKSIM_malloc(bitstr_size(result->size)); ASSERT ((result->validmap != NULL) && (result->dirtymap != NULL)); }

This specifies the total size of the cache in blocks.


PARAM Max request size		I	1 
TEST i >= 0
INIT result->maxreqsize = i;

This specifies the maximum request size to be served by the cache.  This
value does not actually affect the simulated cache's behavior.
Rather, higher-level system components (e.g.,~the device driver in
DiskSim) acquire this information at initialization time and break up
larger requests to accommodate it.  0~indicates that there is no
maximum request size.

PARAM Write scheme		I	1 
TEST RANGE(i,CACHE_WRITE_MIN,CACHE_WRITE_MAX)
INIT result->writescheme = i;

This specifies the policy for handling write requests.  

1~indicates that new data are always synchronously written to the
backing store before indicating completion.

2~indicates a write-through scheme where requests are immediately
initiated for writing out the new data to the backing store, but the
original write requests are considered complete as soon as the new
data is cached.

3~indicates a write-back scheme where completions are reported
immediately and dirty blocks are held in the cache for some time
before being written out to the backing store.


PARAM Flush policy		I	1 
TEST RANGE(i,CACHE_FLUSH_MIN,CACHE_FLUSH_MAX)
INIT result->flush_policy = i;

This specifies the policy for flushing dirty blocks to the backing store
(assuming a write-back scheme for handling write requests).

0~indicates that dirty blocks are written back ``on demand''
(i.e.,~only when the allocation/replacement policy needs to reclaim
them).

1~indicates write-back requests are periodically initiated for all
dirty cache blocks.

PARAM Flush period		D	1 
TEST d >= 0
INIT result->flush_period = d;

This specifies the time between periodic write-backs of all dirty cache
blocks (assuming a periodic flush policy).

PARAM Flush idle delay		D	1 
TEST (d >= 0) || (d == -1.0)
INIT result->flush_idledelay = d;

This specifies the amount of contiguous idle time that must be observed
before background write-backs of dirty cache blocks are initiated.
Any front-end request processing visible to the cache resets the idle
timer.  -1.0~indicates that idle background flushing is disabled.

# !!! Both of these devices MUST be instantiated before a cachedev
# is instantiated, otherwise, getdevbyname() will fail, etc.

PARAM Cache device		S	1 
TEST getdevbyname(s, &result->cache_devno, 0, 0)

The device used for the cache.

PARAM Cached device		S	1 
TEST getdevbyname(s, &result->real_devno, 0, 0)

The device whose data is being cached.