Red Hat Bugzilla – Bug 191055
Small write and gfs_fsync performance issue
Last modified: 2010-01-11 22:11:20 EST
+++ This bug was initially created as a clone of Bug #190950 +++
Description of problem:
Customer supplies a test program that is said to well represent
their running environment. Other than 10x less bandwidth (from
application point of view) when compared with EXT3, GFS also
generates 200MB of disk I/O for 8MB of application data vs.
EXT3's 38MB of disk I/O.
The test program does the following:
1. Create an 8M of temp file and sequentially write to it.
2. Enable its own pthread mutex locks
3. Start the timer
4. Loop 8192 times that
1. "write" 1024 byte of data into random offset
2. "fdatasync", followed by "fsync" after every write
5. Close the file
6. Stop the timer
7. Calculate bandwidth and latency based on time statistics
collected between step 3 to 6.
The program is capable of doing multi-thread run (and many other
features) but we're focusing on the scenario from step 1 to 7
using one single thread.
Version-Release number of selected component (if applicable):
Each ime and every time
Steps to Reproduce: