Nick Piggin wrote:
Christoph Hellwig wrote:
Is that every fork/exec or just under certain cicumstances?
A 5% regression on every fork/exec is not acceptable.
Well after patch2, G5 fork is 3% and exec is 1%, I'd say the P4
numbers will be improved as well with that patch. Then if we have
specific lock/unlock bitops, I hope it should reduce that further.
OK, with the races and missing barriers fixed from the previous patch,
plus the attached one added (+patch3), numbers are better again (I'm not
sure if I have the ppc barriers correct though).
These ops could also be put to use in bit spinlocks, buffer lock, and
probably a few other places too.
2.6.21 1.49-1.51 164.6-170.8 741.8-760.3
+patch 1.71-1.73 175.2-180.8 780.5-794.2
+patch2 1.61-1.63 169.8-175.0 748.6-757.0
+patch3 1.54-1.57 165.6-170.9 748.5-757.5
So fault performance goes to under 5%, fork is in the noise, exec is
still up 1%, but maybe that's noise or cache effects again.