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ative absolute performance and more on scalability of performance as additional processors
are added. After we examine this data, we will examine the multicore performance of the Intel
Core i7 in more detail.
We show the performance for three benchmark sets: SPECintRate, SPECfpRate, and SPECjb-
b2005. The SPECRate benchmarks, which we clump together, illustrate the performance of
these multiprocessors for request-level parallelism, since it is characterized by the parallel and
overlapped execution of independent programs. In particular, nothing other than systems ser-
vices is shared. SPECjbb2005 is a scalable Java business benchmark that models a three-tier
client/server system, with the focus on the server, and is similar to the benchmark used in
SPECPower, which we examined in Chapter 1 . The benchmark exercises the implementations
of the Java Virtual Machine, just in time compiler, garbage collection, threads, and some as-
pects of the operating system; it also tests scalability of multiprocessor systems.
Figure 5.28 shows the performance of the SPECRate CPU benchmarks as core counts are
increased. Nearly linear speedup is achieved as the number of processor chips and hence the
core count is increased.
FIGURE 5.28 The performance on the SPECRate benchmarks for three multicore pro-
cessors as the number of processor chips is increased . Notice for this highly parallel
benchmark, nearly linear speedup is achieved. Both plots are on a log-log scale, so linear
speedup is a straight line.
Figure 5.29 shows similar data for the SPECjbb2005 benchmark. The trade-offs between ex-
ploiting more ILP and focusing on just TLP are complex and are highly workload depend-
ent. SPECjbb2005 is a workload that scales up as additional processors are added, holding the
time, rather than the problem size, constant. In this case, there appears to be ample parallelism
to get linear speedup through 64 cores. We will return to this topic in the concluding remarks,
but first let's take a more detailed look at the performance of the Intel Core i7 in a single-chip,
four-core mode.
 
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