Decimal GetEvenNumberRangeMode(Decimal [] A)
{
if (A == null) return 0;
Return A.EvenNumberRangeMode ();
}
Today we will continue to discuss the WRL system for trace generation. We discussed the effects of direct mapped and associative second level cache. We now review the line size in first and second level cache. When the line size was doubled or quadrupled with a 512 K second level cache, there were reductions in the Cumulative Total CPI and this was independent of the second level size. The improvement was due to decreased contribution of the instruction cache. The data cache remained constant. The improvement in doubling the line size was the same as the improvement in increasing the second level cache size eight times. The effects of doubling the length of the lines in the second level cache from 128 bytes to 256 bytes made no difference. This may be due to too much conflict for long line sizes to be beneficial.
We next review write buffer contributions. The performance of the write buffer varied from program to program. This is mainly due to the sensitivity of the write buffer to both the proportion and distribution of writes in the instructions executed. A write buffer entry is retired every six cycles. If the writes were any more frequent or bunched, it would degrade the performance. The relationship between the proportion of writes in a program and the write buffer performance is clear. The CPI contributed by the write buffer shows a corresponding jump.
There was a case where the percent of writes was frequently in the 15-20% range but the CPI write buffer is usually zero. If the writes were uniformly distributed below a threshold, the write buffer will never fill and a subsequent write will never be delayed. Above the threshold, there may be some delays. Since the second level cache is pipelined into three stages, the processing of a single miss gives the write buffer a chance to retire two entries. If enough misses are interspersed between the two writes, the write buffer may work smoothly Thus the first level data cache miss ratio is the third factor that comes into play.
Although this report doesn't study it, but the effects of entropy on the cache distribution hierarchy could be relevant. The Shannon entropy is defined as negative sum of P(x) log base 2 P(x)
{
if (A == null) return 0;
Return A.EvenNumberRangeMode ();
}
Today we will continue to discuss the WRL system for trace generation. We discussed the effects of direct mapped and associative second level cache. We now review the line size in first and second level cache. When the line size was doubled or quadrupled with a 512 K second level cache, there were reductions in the Cumulative Total CPI and this was independent of the second level size. The improvement was due to decreased contribution of the instruction cache. The data cache remained constant. The improvement in doubling the line size was the same as the improvement in increasing the second level cache size eight times. The effects of doubling the length of the lines in the second level cache from 128 bytes to 256 bytes made no difference. This may be due to too much conflict for long line sizes to be beneficial.
We next review write buffer contributions. The performance of the write buffer varied from program to program. This is mainly due to the sensitivity of the write buffer to both the proportion and distribution of writes in the instructions executed. A write buffer entry is retired every six cycles. If the writes were any more frequent or bunched, it would degrade the performance. The relationship between the proportion of writes in a program and the write buffer performance is clear. The CPI contributed by the write buffer shows a corresponding jump.
There was a case where the percent of writes was frequently in the 15-20% range but the CPI write buffer is usually zero. If the writes were uniformly distributed below a threshold, the write buffer will never fill and a subsequent write will never be delayed. Above the threshold, there may be some delays. Since the second level cache is pipelined into three stages, the processing of a single miss gives the write buffer a chance to retire two entries. If enough misses are interspersed between the two writes, the write buffer may work smoothly Thus the first level data cache miss ratio is the third factor that comes into play.
Although this report doesn't study it, but the effects of entropy on the cache distribution hierarchy could be relevant. The Shannon entropy is defined as negative sum of P(x) log base 2 P(x)
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