On Fri, Mar 04, 2016 at 12:04:39PM -0800, Andrew Morton wrote: > On Thu, 3 Mar 2016 16:43:49 +0900 Joonsoo Kim <js1304@xxxxxxxxx> wrote: > > > > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > > > > > >> +config DEBUG_PAGE_REF > > >> + bool "Enable tracepoint to track down page reference manipulation" > > >> + depends on DEBUG_KERNEL > > >> + depends on TRACEPOINTS > > >> + ---help--- > > >> + This is the feature to add tracepoint for tracking down page > > >> reference > > >> + manipulation. This tracking is useful to diagnosis functional > > >> failure > > >> + due to migration failure caused by page reference mismatch. Be > > > > > > > > > OK. > > > > > >> + careful to turn on this feature because it could bloat some > > >> kernel > > >> + text. In my configuration, it bloats 30 KB. Although kernel text > > >> will > > >> + be bloated, there would be no runtime performance overhead if > > >> + tracepoint isn't enabled thanks to jump label. > > > > > > > > > I would just write something like: > > > > > > Enabling this feature adds about 30 KB to the kernel code, but runtime > > > performance overhead is virtually none until the tracepoints are actually > > > enabled. > > > > Okay, better! > > Andrew, do you want fixup patch from me or could you simply handle it? > > > > This? Yep! Thanks! > > --- a/mm/Kconfig.debug~mm-page_ref-add-tracepoint-to-track-down-page-reference-manipulation-fix-3-fix > +++ a/mm/Kconfig.debug > @@ -82,10 +82,9 @@ config DEBUG_PAGE_REF > depends on DEBUG_KERNEL > depends on TRACEPOINTS > ---help--- > - This is the feature to add tracepoint for tracking down page reference > - manipulation. This tracking is useful to diagnosis functional failure > - due to migration failure caused by page reference mismatch. Be > - careful to turn on this feature because it could bloat some kernel > - text. In my configuration, it bloats 30 KB. Although kernel text will > - be bloated, there would be no runtime performance overhead if > - tracepoint isn't enabled thanks to jump label. > + This is a feature to add tracepoint for tracking down page reference > + manipulation. This tracking is useful to diagnose functional failure > + due to migration failures caused by page reference mismatches. Be > + careful when enabling this feature because it adds about 30 KB to the > + kernel code. However the runtime performance overhead is virtually > + nil until the tracepoints are actually enabled. > _ > > -- > 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> -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
