kernel lock contention and scalability

From: Jonathan Lahr (lahr@sequent.com)
Date: Thu Feb 15 2001 - 13:46:56 EST

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To discover possible locking limitations to scalability, I have collected
locking statistics on a 2-way, 4-way, and 8-way performing as networked
database servers. I patched the [48]-way kernels with Kravetz's multiqueue
patch in the hope that mitigating runqueue_lock contention might better
reveal other lock contention.

In the attached document, I describe my test environment and excerpt
lockstat output to show the more contentious locks for a typical run on
each of my server configurations. I'm interested in comparing these data
to other lock contention data, so information regarding previous or ongoing
lock contention work would be appreciated. I'm aware of timer scalability
work ongoing at people.redhat.com/mingo/scalable-timers, but is anyone
working on reducing sem_ids contention?

-- Jonathan Lahr IBM Linux Technology Center Beaverton, Oregon lahr@us.ibm.com 503-578-3385

text/plain attachment: note.att

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