| Date | Sat, 23 Feb 2008 00:03:45 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH [RT] 00/14] RFC - adaptive real-time locks |
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On Thu, 21 Feb 2008 22:24:20 +0100 Ingo Molnar <mingo@elte.hu> wrote:
> regarding the concept: adaptive mutexes have been talked about in the > past, but their advantage is not at all clear, that's why we havent done > them. It's definitely not an unambigiously win-win concept.
When ext3 was converted from sleeping locks to spinlocks, dbench-on-numaq throughput went up by a factor of ten. I'd expect that what RT has done was a truly awful change for lots of workloads on lots of machines.
Yeah, there's the dont-enable-it-if-you're-doing-that option, but that adds the we-just-doubled-the-number-of-kernels-distros-need-to-ship problem.
Does -rt also make bit_spin_lock preemptible? If not, I'd have thought the change was of little benefit to ext3/jbd and it might as well go back to spinning locks.
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