Mon, 30 Jun 2008

stop_machine latency: the rewrite

Following on from my previous graphs of stop_machine latency, I have new results with my stop_machine simplification patch.

Again, it's the 18-way Power4 box; the simplied stop_machine creates all the threads and moves them into the correct CPUs before starting them. They then step through the state machine themselves, rather than having a central controller.

It's actually marginally worse than the previous:

Since these are different kernel versions, I looked at the baseline latency for both kernels:

Now I need to go back and compare the exact same kernel version, to make sure something else isn't interfering...

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