Messages in this thread | | | Date | Wed, 29 Oct 2008 20:24:12 +1100 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH 2/2] x86: replace BIO_VMERGE_BOUNDARY with BIOVEC_PHYS_MERGEABLE |
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Ingo Molnar wrote: > * FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote: > > >> On Mon, 27 Oct 2008 12:57:00 +0100 >> Jens Axboe <jens.axboe@oracle.com> wrote: >> >> >>> On Mon, Oct 27 2008, Jeremy Fitzhardinge wrote: >>> >>>> Jens Axboe wrote: >>>> >>>>> Pretty much baffles me as well, xen should just need to do >>>>> >>>>> #define BIOVEC_PHYS_MERGEABLE(vec1, vec2) 0 >>>>> >>>>> >>>> It needs to be a runtime switch, since we only want to do this when >>>> actually running under Xen. Also, its possible that the two pages might >>>> actually be physically contiguous, so they could be merged anyway. >>>> >>> Alright, then add a xen_biovec_phys_mergeable(vec1, vec2) in the xen >>> code that actually checks this for real. You can add your switch there >>> as well. Then put the BIOVEC_PHYS_MERGEABLE() in the xen arch includes, >>> done. >>> >>> What Tomo is saying is that this has nothing to do with virtual merging, >>> and he's right. >>> >> Yeah, overriding BIOVEC_PHYS_MERGEABLE perfectly works for Xen. And it >> is not related with BIO_VMERGE_BOUNDARY at all. >> >> Ingo, please put this patch into your tree: >> >> http://marc.info/?l=linux-kernel&m=122482703716620&w=2 >> > > does it have any dependency on: > > Subject: [PATCH 1/2] bio: define __BIOVEC_PHYS_MERGEABLE >
No, they're independent. Defining __BIOVEC_PHYS_MERGEABLE will be useful for the Xen changes I need to make in the wake of Tomo's patch.
J
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