Messages in this thread | | | Date | Mon, 6 Mar 2006 20:58:35 -0800 | From | Mark Fasheh <> | Subject | Re: Ocfs2 performance bugs of doom |
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On Tue, Mar 07, 2006 at 04:34:12AM +0100, Andi Kleen wrote: > Did you actually do some statistics how long the hash chains are? > Just increasing hash tables blindly has other bad side effects, like > increasing cache misses. Yep, the gory details are at:
http://oss.oracle.com/~mfasheh/lock_distribution.csv
This measure was taken about 18,000 locks into a kernel untar. The only change was that I switched things to only hash the last 18 characters of lock resource names.
In short things aren't so bad that a larger hash table wouldn't help. We've definitely got some peaks however. Our in-house laboratory of mathematicians (read: Bill Irwin) is checking out methods by which we can smooth things out a bit more :) --Mark
-- Mark Fasheh Senior Software Developer, Oracle mark.fasheh@oracle.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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