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

CHAPTER 6. MICROBENCHMARKS – OTHER FUNDAMENTAL OPERATIONS 58
avg # cycles per processor
4e+07
3e+07
2e+07
1e+07
0e+00
2 4 6 8 10 12
# processors
Original read test
Original read test: perfect memory
Stat
Figure 6.12: Stat.
6.4 File Stat
avg # cycles per processor
1e+08
5e+07
0e+00
2 4 6 8 10 12
# processors
Stat + processing
Stat
Figure 6.13: Stat – +processing.
avg # cycles per processor
2e+07
1.5e+7
1e+07
5e+06
0e+00
2 4 6 8 10 12
# processors
Stat + processing
Stat
Figure 6.14: Stat – +processing.
We examined the scalability of the getAttribute() operation in the next set of experiments. As described
in Section 3.6.1 on page 24, getAttribute() returns the attributes of a target file or directory identified by a
file token. This experiment was basically a subset of the unoptimized extent-based read test in Section 5.2
since, in the file stat experiment, the file status operation is executed but file block reading and file status
updating is not performed. Each thread executed on its own processor, disk, and file. For each thread, the
getAttribute() file system operation was performed 3136 times on its own extent-based file, matching the
number of times the operation was performed on the superset of the experiment (Section 5.2), and allowing
for easy comparison of results. The results of using unoptimized HFS, shown in Figure 6.12 1 , are similar
to the extent-based read test (Section 5.3), since the experiment was simply a subset of the read test.
6.4.1 + Processing
This experimental configuration was a slightly more realistic file stat test. The configuration is similar to
Section 6.4, except that it processes the file status data into the standard Unix format before returning from
the call. More specifically, it converts the HFS format of file status to the more widely used Unix/Linux/GNU
file status format. As shown in Figure 6.13 2 and Figure 6.14 3 , the results were fairly similar to the previous
file stat experiment in Section 6.4 as might be expected. It took slightly longer for the extra processing,
however the maximum error bar range on 12 processors was much greater.
1 Error bars were removed from the unoptimized 12 processor configuration.
2 Error bars were removed from the unprocessed 12 processor configuration.
3 Error bars were removed from the 12 processor configurations.