On Thu, 27 Feb 2014 13:59:59 -0800 Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> wrote: > On 02/27/2014 11:53 AM, Kirill A. Shutemov wrote: > > +#define FAULT_AROUND_ORDER 4 > > +#define FAULT_AROUND_PAGES (1UL << FAULT_AROUND_ORDER) > > +#define FAULT_AROUND_MASK ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1) > > Looking at the performance data made me think of this: do we really want > this to be static? It seems like the kind of thing that will cause a > regression _somewhere_. Yes, allowing people to tweak it at runtime would improve testability a lot. I don't think we want to let yet another tunable out into the wild unless we really need to - perhaps a not-for-mainline add-on patch, or something in debugfs so we have the option of taking it away later. > Also, the folks with larger base bage sizes probably don't want a > FAULT_AROUND_ORDER=4. That's 1MB of fault-around for ppc64, for example. Yup, we don't want the same app to trigger dramatically different kernel behaviour when it is moved from x86 to ppc. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
