| Date | Fri, 11 Feb 2022 18:44:39 +0100 | Subject | Re: [PATCH 46/49] mm/mempolicy: replace nodes_weight with nodes_weight_eq | From | Christophe JAILLET <> |
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Le 10/02/2022 à 23:49, Yury Norov a écrit : > do_migrate_pages() calls nodes_weight() to compare the weight > of nodemask with a given number. We can do it more efficiently with > nodes_weight_eq() because conditional nodes_weight() may stop > traversing the nodemask earlier, as soon as condition is (or is not) > met. > > Signed-off-by: Yury Norov <yury.norov@gmail.com> > --- > mm/mempolicy.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 7c852793d9e8..56efd00b1b6e 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -1154,7 +1154,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from, > * [0-7] - > [3,4,5] moves only 0,1,2,6,7. > */ > > - if ((nodes_weight(*from) != nodes_weight(*to)) && > + if (!nodes_weight_eq(*from, nodes_weight(*to)) && > (node_isset(s, *to)))
Hi,
I've not looked in details, but would it make sense to hoist the "(nodes_weight(*from) != nodes_weight(*to))" test out of the for_each_node_mask() to compute it only once?
'from' and 'to' look unmodified in the loop.
Just my 2c, CJ
> continue; >
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