On Tue, Apr 21, 2009 at 02:30:55PM -0700, David Daney wrote: > This patch set (against 2.6.29.1) creates a vdso and moves the signal > trampolines to it from their previous home on the stack. > > Tested with a 64-bit kernel on a Cavium Octeon cn3860 where I have the > following results from lmbench2: > > Before: > n64 - Signal handler overhead: 14.517 microseconds > n32 - Signal handler overhead: 14.497 microseconds > o32 - Signal handler overhead: 16.637 microseconds > > After: > > n64 - Signal handler overhead: 7.935 microseconds > n32 - Signal handler overhead: 7.334 microseconds > o32 - Signal handler overhead: 8.628 microseconds Nice numbers, and something that will be even more critical as real-time features are added and used! > Comments encourged. Only one comment, which I would not want to hold up acceptance: based on some numbers sent out recently, it looks like the kernel is experiencing some performance issues with exec() and I think this change will make it slightly slower. You could avoid this by deferring installation of the trampoline to the first use of a system call that registers a signal handler. David VomLehn
