Messages in this thread | | | Date | Tue, 13 Aug 2013 09:02:13 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [patch 2/2] [PATCH] mm: Save soft-dirty bits on file pages |
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On Mon, Aug 12, 2013 at 03:28:06PM -0700, Andy Lutomirski wrote: > > > > You could have #undefed _mfrob and __frob after using them, but whatever.
Sure, for some reason I forgot to do that. Will send update on top.
> > I saved this patch to wave at the x86 guys for 3.12. I plan to merge > > mm-save-soft-dirty-bits-on-file-pages.patch for 3.11. > > > >> Guys, is there a reason for "if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE" > >> test present in this pgtable-2level.h file at all? I can't imagine > >> where it can be false on x86. > > > > I doubt if "Guys" read this. x86 maintainers cc'ed.
Thanks!
> > +#define _mfrob(v,r,m,l) ((((v) >> (r)) & (m)) << (l)) > > +#define __frob(v,r,l) (((v) >> (r)) << (l)) > > + > > #ifdef CONFIG_MEM_SOFT_DIRTY > > If I'm understanding this right, the idea is to take the bits in the > range a..b of v and stick them at c..d, where a-b == c-d. Would it > make sense to change this to look something like > > #define __frob(v, inmsb, inlsb, outlsb) ((v >> inlsb) & ((1<<(inmsb - > inlsb + 1)-1) << outlsb)
There is a case when you don't need a mask completely. And because this pte conversion is on hot path and time critical I kept generated code as it was (even if that lead to slightly less clear source code).
> For extra fun, there could be an __unfrob macro that takes the same > inmsg, inlsb, outlsb parameters but undoes it so that it's (more) > clear that the operations that are supposed to be inverses are indeed > inverses.
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