Messages in this thread | | | Date | Wed, 22 Apr 2009 13:24:26 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH 16/22] Do not setup zonelist cache when there is only one node |
| |
On Wed, 22 Apr 2009, Mel Gorman wrote:
> There is a zonelist cache which is used to track zones that are not in > the allowed cpuset or found to be recently full. This is to reduce cache > footprint on large machines. On smaller machines, it just incurs cost > for no gain. This patch only uses the zonelist cache when there are NUMA > nodes. > > Signed-off-by: Mel Gorman <mel@csn.ul.ie> > Reviewed-by: Christoph Lameter <cl@linux-foundation.org> > --- > mm/page_alloc.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 7f45de1..e59bb80 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1467,8 +1467,11 @@ this_zone_full: > if (NUMA_BUILD) > zlc_mark_zone_full(zonelist, z);
If zonelist caching is never used for UMA machines, why should they ever call zlc_mark_zone_full()? It will always dereference zonelist->zlcache_ptr and immediately return without doing anything.
Wouldn't it better to just add
if (num_online_nodes() == 1) continue;
right before this call to zlc_mark_zone_full()? This should compile out the remainder of the loop for !CONFIG_NUMA kernels anyway.
> try_next_zone: > - if (NUMA_BUILD && !did_zlc_setup) { > - /* we do zlc_setup after the first zone is tried */ > + if (NUMA_BUILD && !did_zlc_setup && num_online_nodes() > 1) { > + /* > + * we do zlc_setup after the first zone is tried but only > + * if there are multiple nodes make it worthwhile > + */ > allowednodes = zlc_setup(zonelist, alloc_flags); > zlc_active = 1; > did_zlc_setup = 1; > -- > 1.5.6.5
| |