On 05/17/2017 10:09 AM, Michal Hocko wrote: > From: Michal Hocko <mhocko@xxxxxxxx> > > While converting drm_[cm]alloc* helpers to kvmalloc* variants Chris > Wilson has wondered why we want to try kmalloc before vmalloc fallback > even for larger allocations requests. Let's clarify that one larger > physically contiguous block is less likely to fragment memory than many > scattered pages which can prevent more large blocks from being created. > > Suggested-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > --- > mm/util.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/util.c b/mm/util.c > index 464df3489903..87499f8119f2 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -357,7 +357,10 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node) > WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL); > > /* > - * Make sure that larger requests are not too disruptive - no OOM > + * We want to attempt a large physically contiguous block first because > + * it is less likely to fragment multiple larger blocks and therefore > + * contribute to a long term fragmentation less than vmalloc fallback. > + * However make sure that larger requests are not too disruptive - no OOM > * killer and no allocation failure warnings as we have a fallback > */ > if (size > PAGE_SIZE) { > -- 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>