On Fri, 2005-08-05 at 10:53, Andi Kleen wrote: > On Fri, Aug 05, 2005 at 10:21:38AM -0500, Adam Litke wrote: > > Below is a patch to implement demand faulting for huge pages. The main > > motivation for changing from prefaulting to demand faulting is so that > > huge page allocations can follow the NUMA API. Currently, huge pages > > are allocated round-robin from all NUMA nodes. > > I think matching DEFAULT is better than having a different default for > huge pages than for small pages.
I am not exactly sure what the above means. Is 'DEFAULT' a system default numa allocation policy? > In general more programs are happy with local memory than remote memory. I totally agree. > Also it makes it consistent. > > > > > The default behavior in SLES9 for i386 is to use demand faulting with > > NUMA policy-aware allocations. To my knowledge, this continues to work > > Not sure what you're trying to say here. All allocations are NUMA policy > aware. Sorry, I really wasn't clear. That statement referred to huge pages specifically. I was trying to point out that numa policy-aware huge page allocation combined with demand faulting in SLES9/i386 has been a success. > > well in practice. Thanks to consolidated hugetlb code, switching the > > behavior requires changing only one fault handler. The bulk of the > > patch just moves the logic from hugelb_prefault() to > > hugetlb_pte_fault(). > > Are you sure you fixed get_user_pages to handle this properly? It doesn't > like it. Unless I am missing something, the call to follow_hugetlb_page() in get_user_pages() is just an optimization. Removing it means follow_page() will be called individually for each PAGE_SIZE page in the huge page. We can probably do better but I didn't want to cloud this patch with that logic. -- Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/