Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932249Ab3GOO1s (ORCPT ); Mon, 15 Jul 2013 10:27:48 -0400 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:40051 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932090Ab3GOO1q (ORCPT ); Mon, 15 Jul 2013 10:27:46 -0400 From: "Aneesh Kumar K.V" To: Joonsoo Kim , Andrew Morton Cc: Rik van Riel , Mel Gorman , Michal Hocko , KAMEZAWA Hiroyuki , Hugh Dickins , Davidlohr Bueso , David Gibson , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Joonsoo Kim Subject: Re: [PATCH 4/9] mm, hugetlb: fix and clean-up node iteration code to alloc or free In-Reply-To: <1373881967-16153-5-git-send-email-iamjoonsoo.kim@lge.com> References: <1373881967-16153-1-git-send-email-iamjoonsoo.kim@lge.com> <1373881967-16153-5-git-send-email-iamjoonsoo.kim@lge.com> User-Agent: Notmuch/0.15.2+167~g5306b2b (http://notmuchmail.org) Emacs/24.3.50.1 (x86_64-unknown-linux-gnu) Date: Mon, 15 Jul 2013 19:57:37 +0530 Message-ID: <87y597j3ty.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13071514-2674-0000-0000-000009CE3069 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3246 Lines: 113 Joonsoo Kim writes: > Current node iteration code have a minor problem which do one more > node rotation if we can't succeed to allocate. For example, > if we start to allocate at node 0, we stop to iterate at node 0. > Then we start to allocate at node 1 for next allocation. Can you explain the problem in a bit more detail > > I introduce new macros "for_each_node_mask_to_[alloc|free]" and > fix and clean-up node iteration code to alloc or free. > This makes code more understandable. > I found the existing code more readable. Obviously I haven't yet figured out the problem you have observed with the code. > Signed-off-by: Joonsoo Kim > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 0067cf4..a838e6b 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -752,33 +752,6 @@ static int hstate_next_node_to_alloc(struct hstate *h, > return nid; > } > > -static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) > -{ > - struct page *page; > - int start_nid; > - int next_nid; > - int ret = 0; > - > - start_nid = hstate_next_node_to_alloc(h, nodes_allowed); > - next_nid = start_nid; > - > - do { > - page = alloc_fresh_huge_page_node(h, next_nid); > - if (page) { > - ret = 1; > - break; > - } > - next_nid = hstate_next_node_to_alloc(h, nodes_allowed); > - } while (next_nid != start_nid); > - > - if (ret) > - count_vm_event(HTLB_BUDDY_PGALLOC); > - else > - count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); > - > - return ret; > -} > - > /* > * helper for free_pool_huge_page() - return the previously saved > * node ["this node"] from which to free a huge page. Advance the > @@ -797,6 +770,42 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) > return nid; > } > > +#define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \ > + for (nr_nodes = nodes_weight(*mask), \ > + node = hstate_next_node_to_alloc(hs, mask); \ > + nr_nodes > 0 && \ > + ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \ > + nr_nodes--) > + > +#define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \ > + for (nr_nodes = nodes_weight(*mask), \ > + node = hstate_next_node_to_free(hs, mask); \ > + nr_nodes > 0 && \ > + ((node = hstate_next_node_to_free(hs, mask)) || 1); \ > + nr_nodes--) > + > +static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) > +{ > + struct page *page; > + int nr_nodes, node; > + int ret = 0; > + > + for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { This check for nodes_weight and fail right ? (nr_nodes == 0). That is not the case with the existing code. It will allocate from h->next_nid_to_alloc. Is that ok ? > + page = alloc_fresh_huge_page_node(h, node); > + if (page) { > + ret = 1; > + break; > + } > + } > + > + if (ret) > + count_vm_event(HTLB_BUDDY_PGALLOC); > + else > + count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); > + > + return ret; > +} > + -aneesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/