Messages in this thread | | | Date | Thu, 07 Feb 2002 11:51:22 -0800 | From | Dave Hansen <> | Subject | Re: [RFC] New locking primitive for 2.5 |
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Andrew Morton wrote: > Robert Love wrote: >>On Thu, 2002-02-07 at 10:38, Martin Wirth wrote: >>Some of the talk I've heard has been toward an adaptive lock. These are >>locks like Solaris's that can spin or sleep, usually depending on the >>state of the lock's holder. Another alternative, which I prefer since >>it is much less overhead, is a lock that spins-then-sleeps >>unconditionally. > I dunno. The spin-a-bit-then-sleep lock has always struck me as > i_dont_know_what_the_fuck_im_doing_lock(). Martin's approach puts > the decision in the hands of the programmer, rather than saying > "Oh gee I goofed" at runtime.
The spin-then-sleep lock could be interesting as a replacement for the BKL in places where a semaphore causes performance degredation. In quite a few places where we replaced the BKL with a more finely grained semapore (not a spinlock because we needed to sleep during the hold), instead of spinning for a bit, it would schedule instead. This was bad :). Spin-then-sleep would be great behaviour in this situation.
-- Dave Hansen haveblue@us.ibm.com
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