On Wed, 29 May 2013 14:20:12 -0700 Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote: > > Do we have any performance testing results? They're pretty important > > for a performance-improvement patch ;) > > > > I've done a repeated brk test of 800KB (from will-it-scale test suite) > with 80 concurrent processes on a 4 socket Westmere machine with a > total of 40 cores. Without the patch, about 80% of cpu is spent on > spin-lock contention within the vm_committed_as counter. With the patch, > there's a 73x speedup on the benchmark and the lock contention drops off > almost entirely. Only a 73x speedup? I dunno what they pay you for ;) How serious is this performance problem in real-world work? For something of this magnitude we might want to backport the patch into earlier kernels (because most everyone who uses those kernels will be doing this anyway). However such an act would require a pretty clear explanation of the benefit which end-users will see. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>