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ARM1176JZ-S, cache confg: effective cache size calculation
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ARM1176JZ-S, cache confg: effective cache size calculation
deven deven
over 12 years ago
Note: This was originally posted on 22nd February 2009 at
http://forums.arm.com
Hello,
1) I am using ARM1176JZ-S core with WinCE Platform. The cache memory is configured as follows
DCache: 128 sets, 4 ways, 32 line size, 16384 size
ICache: 128 sets, 4 ways, 32 line size, 16384 size
Now I want to know the effective data cache size, I mean the total data from the main memory
could be cached and accessed without cache trashing within a function.
2) Is the cache set size(128 sets) and cache block/segment(of other processors) size are same?
Kindly reply this mail, thanks in advance
Regards,
Deven
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Peter Harris
over 12 years ago
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Note: This was originally posted on 9th March 2009 at http://forums.arm.com Assuming that your QUERY_START and QUERY_END macros are calling a system function to get the time stamp, I would think that you...
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Peter Harris
over 12 years ago
Note: This was originally posted on 22nd February 2009 at
http://forums.arm.com
> I mean the total data from the main memory
16KB for data, and 16KB for instructions are the critical numbers you will want. The rest is just noise unless you design a pathological algorithm which really abuses the cache.
Some systems also include a L2 cache which can cache more data between the L1 caches and the main memory.
> Is the cache set size(128 sets) and cache block/segment(of other processors) size are same?
It varies - basically the scheme you outline means that for any 1 address there are 4 possible places (ways) where the data may reside. 128 sets (cache lines) * 4 ways * 32-bytes per cache line = 16 KB. Four 4-way caches are pretty common as they give a good trade-off between speed and cache utilization for typical code.
For most caches on ARM systems the number of ways is fixed, but number of sets depends on the size of the cache. In this case 64 sets = 8KB cache, 128 sets = 16KB cache, etc.
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Peter Harris
over 12 years ago
Note: This was originally posted on 22nd February 2009 at
http://forums.arm.com
> I mean the total data from the main memory
16KB for data, and 16KB for instructions are the critical numbers you will want. The rest is just noise unless you design a pathological algorithm which really abuses the cache.
Some systems also include a L2 cache which can cache more data between the L1 caches and the main memory.
> Is the cache set size(128 sets) and cache block/segment(of other processors) size are same?
It varies - basically the scheme you outline means that for any 1 address there are 4 possible places (ways) where the data may reside. 128 sets (cache lines) * 4 ways * 32-bytes per cache line = 16 KB. Four 4-way caches are pretty common as they give a good trade-off between speed and cache utilization for typical code.
For most caches on ARM systems the number of ways is fixed, but number of sets depends on the size of the cache. In this case 64 sets = 8KB cache, 128 sets = 16KB cache, etc.
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