Andi Kleen writes: > Andrew Haley <[EMAIL PROTECTED]> writes: > > > Howard Chu writes: > > > > > A bit of a minor mystery. Not a problem, just a curiosity. If > > > someone knew off the top of their head a reason for it, that'd be > > > cool, but otherwise no sweat. > > > > It's possible, although unlikley, that the optimized code has worse > > cache behaviour. No way to know better without doing some profiling. > > It's quite possible if he hits the conditional store "optimization" > (that actually adds unnecessary cache misses) that was recently discussed > in the load thread safety thread.
Possibly. I'm guessing that what we are actually seeing is something like an acutely timing-sensitive race condition, where making some threads faster causes pessimal cache behaviour. It's a really interesting problem. :-) Andrew. -- Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, UK Registered in England and Wales No. 3798903
