Andrew Morton <[EMAIL PROTECTED]> writes: > > We do have the `used_math' optimisation in there which attempts to avoid > doing the FP save/restore if the app isn't actually using math. But > <ancient recollections> there's code in glibc startup which always does a > bit of float, so that optimisation is always defeated. There was some > discussion about periodically setting tasks back into !used_math state to > try to restore the optimisation for tasks which only do a little bit of FP, > but nothing actually got done.
Actually we reset the flag on every context switch, so that works just fine. But I was considering to do it less often so that we switch the FP state non lazily for FP intensive processes and avoid the overhead of all these exceptions. -Andi P.S.: Original profile data looks a bit fishy. Normally avoiding a single function call should not make tht much difference unless you call it in a inner loop, but that is not the case here. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
