On 05/10/2011 12:09 AM, Bob Evans wrote: > I am using 2.6.35.11-83.fc14.x86_64 (stock from Fedora Core 14). > > Did anything else change? How exactly do you do the file writes? What > block size do you use? Is there a lot of create / delete churn? > > I ask because I believe both write block size and the degree of free > space fragmentation matter. Larger block sizes and systems with more > free space fragmentation may mitigate the issue.
Right. I'd suspect fragmentation in an older volume would reduce the likelihood that you'd have very large extents. > Can you try a simple dd test? Copy from /dev/zero with (default) 512 > byte blocksize and watch the jfsCommit CPU usage as the file gets > larger. The hard part is that it matters how exactly JFS allocates > blocks so you might have to repeat this test a few times to see it > happening. You may want to compare the results of doing this on an existing volume, and a newly formatted one. I suspect the problem is a lot worse on the new one. ------------------------------------------------------------------------------ Achieve unprecedented app performance and reliability What every C/C++ and Fortran developer should know. Learn how Intel has extended the reach of its next-generation tools to help boost performance applications - inlcuding clusters. http://p.sf.net/sfu/intel-dev2devmay _______________________________________________ Jfs-discussion mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jfs-discussion
