On Tue, 2011-04-19 at 13:06 -0700, Andrew Morton wrote: > On Fri, 01 Apr 2011 14:12:59 +0200 > Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote: > > > Remove the first obstackle towards a fully preemptible mmu_gather. > > > > The current scheme assumes mmu_gather is always done with preemption > > disabled and uses per-cpu storage for the page batches. Change this to > > try and allocate a page for batching and in case of failure, use a > > small on-stack array to make some progress. > > > > Preemptible mmu_gather is desired in general and usable once > > i_mmap_lock becomes a mutex. Doing it before the mutex conversion > > saves us from having to rework the code by moving the mmu_gather > > bits inside the pte_lock. > > > > Also avoid flushing the tlb batches from under the pte lock, > > this is useful even without the i_mmap_lock conversion as it > > significantly reduces pte lock hold times. > > There doesn't seem much point in reviewing this closely, as a lot of it > gets tossed away later in the series.. That's a result of breaking patches along concept boundaries :/ > > free_pages_and_swap_cache(tlb->pages, tlb->nr); > > It seems inappropriate that this code uses > free_page[s]_and_swap_cache(). It should go direct to put_page() and > release_pages()? Please review this code's implicit decision to pass > "cold==0" into release_pages(). Well, that isn't new with this patch, however it does look to be correct. We're freeing user pages, those could indeed still be part of the swapcache. Furthermore, the PAGEVEC_SIZE split in free_pages_and_swap_cache() alone makes it worth calling that over release_pages(). As to the cold==0, I think that too is correct since we don't actually touch the pages themselves and we have no inkling as to their cache state, we're simply wiping out user pages. > > -static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) > > +static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) > > I wonder if all the inlining which remains in this code is needed and > desirable. Probably not, the big plan was to make everybody use the generic code and then move it into mm/memory.c or so. But I guess I can have asm-generic/tlb.h define HAVE_GENERIC_MMU_GATHER and make the compilation in mm/memory.c conditional on that (or generate lots of Kconfig churn). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href