On 01/22/15 at 11:22am, Rik van Riel wrote: > On 01/22/2015 11:19 AM, Davidlohr Bueso wrote: > > On Thu, 2015-01-22 at 15:57 +0800, WANG Chao wrote: > >> Hi, Davidlohr > >> > >> On 01/21/15 at 11:46pm, Davidlohr Bueso wrote: > >>> On Thu, 2015-01-22 at 14:29 +0800, WANG Chao wrote: > >>>> Add a new kconfig option VMACACHE_SHIFT (as a power of 2) to specify the > >>>> number of slots vma cache has for each thread. Range is chosen 0-4 (1-16 > >>>> slots) to consider both overhead and performance penalty. Default is 2 > >>>> (4 slots) as it originally is, which provides good enough balance. > >>>> > >>> > >>> Nack. I don't feel comfortable making scalability features of core code > >>> configurable. > >> > >> Out of respect, is this a general rule not making scalability features > >> of core code configurable? > > > > I doubt its a rule, just common sense. Users have no business > > configuring such low level details. The optimizations need to > > transparently work for everyone. > > There may sometimes be a good reason for making this kind of > thing configurable, but since there were no performance > numbers in the changelog, I have not seen any such reason for > this particular change :) True. I didn't run any kind of benchmark, thus no numbers here. This is purely hypothetical. I'm glad to run some tests. For the sake of consistency, could you please show me a hint how do you measure at the first place? I can do hit-rate, but I don't know how you measure cpu cycles. Could you elaborate? Thanks WANG Chao -- 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>