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

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CHAPTER 6. MICROBENCHMARKS – OTHER FUNDAMENTAL OPERATIONS 59 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 + processing optimized Figure 6.15: Stat – +processing, optimized. avg # cycles per processor 1e+06 5e+05 0e+00 6.4.2 + Processing, Optimized 2 4 6 8 10 12 # processors Stat + processing optimized Figure 6.16: Stat – +processing, optimized, magnified. avg # cycles per processor 4e+09 3e+09 2e+09 1e+09 0e+00 2 4 6 8 10 12 # processors Unoptimized Figure 6.17: Stat – +name lookup. This experiment examined the impact of implementing all optimizations. These optimizations included all the optimizations of the read experiments: 1. Padded ORS hash list headers. 2. Padded ORS and block cache entries. 3. Padded all other critical data structures in the ORS and block cache systems, such as locks and waiting I/O data structures (shown in Figure 3.4 and Figure 3.5). 4. Modified hash functions. (ORS and block cache) 5. Increased size of hash tables. (ORS and block cache) 6. Increased initial pool of block cache entries from 20 to 200. 7. Elimination of the block cache free list. 8. Use of fine grain locks in the block cache. For simplicity, the K42 padding facilities were used rather than manually padding and aligning the data structures. The results, shown in Figure 6.15 and Figure 6.16, indicate good scalability. 6.4.3 Stat with Name Lookup The purpose of the next experiment was to more accurately emulate a standard Unix stat() file system call 4 . Each operation of the test begins with a name lookup to obtain the target file token and is followed by an operation to obtain the file status. This experiment is similar to the configuration in the file lookup test (Section 6.3.1) using unoptimized HFS. Each thread performed a file look up of DiskXXX:/directory1/ directory2/directory3/directory4/lookatme.txt to obtain the file token, followed by a getAttribute() file system call and attribute processing, all repeated 1000 times, allowing for easy comparison with the 4 int stat(const char *file name, struct stat *buf)
CHAPTER 6. MICROBENCHMARKS – OTHER FUNDAMENTAL OPERATIONS 60 results in Section 6.3.1. The files were regular, random-access files 5 and the initial pool of block cache entries was set to 200 instead of the default of 20. All threads were executed in parallel and each was assigned its own processor and disk. The results, shown in Figure 6.17, are similar to the results for the file name lookup experiment in Section 6.3.1. Scalability was poor beyond 2 processors. 6.4.4 Stat with Name Lookup, All Optimizations This experiment examined the impact of implementing all optimizations in the getAttribute() with name lookup workload. This configuration included all the optimizations we used previously. The results, shown in Figure 6.18 and Figure 6.19, indicate that scalability was good but not ideal since it took twice as long for each thread to execute on 12 processors than on 1 processor. The results were very similar to the results in Section 6.3.2 that examine the optimized name lookup operation, indicating that the name lookup portion of the task was the rate limiting component where as the getAttribute() portion scaled well, as shown in Section 6.4.2. The 8 processor results exhibited the same anomaly as described in Section 5.5.7, resulting in the lower error bar in the graph. Fortunately, performance trends show that thread execution times appear to stabilize from 8 processors onwards. 6.4.5 Summary The optimizations implemented from the file read experiments were applicable to the file stat operation of the file system. File stat scalability was improved drastically. Ideal scalability was achieved in the getAttribute() portion of the task, whereas the name lookup portion performed relatively well but did not achieve ideal scalability. 6.5 Regular File Write Test This section examines the scalability of the write operation on regular, random-access-based files. Each thread sequentially writes a 4,096,000 byte regular, random-access-based file to its own disk while running on its own processor. The operation causes meta-data to accumulate in the caches. The flushing of the caches to disk was disabled to measure ideal file writing conditions. No optimizations were implemented for this initial base test. The results, shown in Figure 6.20, indicate that scalability was poor beyond 2 processors, closely mirroring the results of the unoptimized regular file read experiment in Section 5.5.1. 5 In terms of the actions taken by the file system during the getAttribute() operation, there is no difference between extentbased or regular, random-access files. Consequently, either file types can be used for the getAttribute experiments.
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Performance Analysis and Optimizati
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Acknowledgements This thesis has be
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4.6 Measurements Taken and Graph In
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List of Tables 3.1 File system inte
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6.1 Create. . . . . . . . . . . . .
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CHAPTER 1. INTRODUCTION AND MOTIVAT
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CHAPTER 1. INTRODUCTION AND MOTIVAT
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CHAPTER 2. BACKGROUND AND RELATED W
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Page 95 and 96: Bibliography [1] Gene M. Amdahl. Va
Page 97 and 98: BIBLIOGRAPHY 88 [33] David Kotz, So
Page 99: BIBLIOGRAPHY 90 [71] Keith A. Smith
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