Performance Analysis and Optimization of the Hurricane File System ...

CHAPTER 6. MICROBENCHMARKS – OTHER FUNDAMENTAL OPERATIONS 55
avg # cycles per processor
1e+10
8e+09
6e+09
4e+09
2e+09
0e+00
2 4 6 8 10 12
# processors
Unoptimized 20 pool
Figure 6.7: Lookup – unoptimized.
6.2.4 + 200 Entries Pool
avg # cycles per processor
1e+10
8e+09
6e+09
4e+09
2e+09
0e+00
2 4 6 8 10 12
# processors
Unoptimized 20 pool
Unoptimized 200 pool
Figure 6.8: Lookup – 200 initial
pool.
avg # cycles per processor
4e+09
3e+09
2e+09
1e+09
0e+00
2 4 6 8 10 12
# processors
Unoptimized 200 pool
Figure 6.9: Lookup – 200 initial
pool, magnified.
Influenced by the results that will be shown in Section 6.3.1 for the file name lookup workload, the initial
pool of block cache entries was increased from 20 to 200 to resolve a potential anomaly in the block cache
entry allocation algorithm. This experiment is otherwise identical in configuration to Section 6.2.3. The
results, as shown in Figure 6.6, indicate that the small initial pool of block cache entries was not the cause
of the scalability problem.
6.2.5 Summary
The optimizations implemented from file read experiments were applicable to the file creation operation.
File creation scalability was improved drastically. On 12 processors, approximately an order of magnitude
of improvement was achieved. However, ideal scalability was not achieved since threads performed 3 times
slower on a 12 processor configuration than on a uniprocessor configuration. Even worse, performance trends
indicate that thread execution time will continue to grow linearly past 12 processors. We were unable to
improve scalability any further for this particular workload
6.3 File Name Lookup
In this set of experiments, we examine the scalability of the file name lookup operation. As described in
Section 3.6.2 on page 25, the name lookup operation returns a file token identifier for a given path name.
The file token allows for easy identification of the target file by the file system and is used by clients to
identify specific files.
In the first experiment, the unoptimized HFS configuration of Section 5.2 was used. Each thread per-
formed a file look up of the same, one file: DiskXXX:/directory1/directory2/directory3/directory4/