From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from there (h164n1fls31o925.telia.com [213.65.254.164]) by maild.telia.com (8.11.2/8.11.0) with SMTP id f7MNoZp17510 for ; Thu, 23 Aug 2001 01:50:35 +0200 (CEST) Message-Id: <200108222350.f7MNoZp17510@maild.telia.com> Content-Type: text/plain; charset="iso-8859-1" From: Roger Larsson Subject: [PATCH NG] alloc_pages_limit & pages_min Date: Thu, 23 Aug 2001 01:46:12 +0200 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org List-ID: Hi, [Note: not tested yet... but it might be hard to trigger] After discussions with Riel and some additions... * The original code had a little bug in those cases when - kreclaimd were not allowed to run for a LONG time... Lots of kernel activity, RT tasks, or code running around for a long time allocating memory. - there were lots of inactive clean pages - pages were allocated without direct_reclaim (higher order) (networking might be one candidate) it could result in using up ALL free pages! This patch tries to prevent this situation in several ways: 1) Do not allow to alloc a free page when they are critically low. [last line of patch] 2) If direct reclaims are allowed do some additional work. reclaim & free until pages_min, alloc one page, reclaim and free until pages_low Q) Nothing is done to force execution of kreclaimd, if no process that can direct_reclaim allocs a page - what will happen then? [unlikely but...] /RogerL -- Roger Larsson Skelleftea Sweden ******************************************* Patch prepared by: roger.larsson@norran.net with comments from Riel --- linux/mm/page_alloc.c.orig Wed Aug 22 13:36:57 2001 +++ linux/mm/page_alloc.c Thu Aug 23 01:15:17 2001 @@ -253,11 +253,35 @@ if (z->free_pages + z->inactive_clean_pages >= water_mark) { struct page *page = NULL; - /* If possible, reclaim a page directly. */ - if (direct_reclaim) + + /* + * Reclaim a page from the inactive_clean list. + * If needed, refill the free list up to the + * low water mark. + */ + if (direct_reclaim) { page = reclaim_page(z); - /* If that fails, fall back to rmqueue. */ - if (!page) + + while (page && z->free_pages < z->pages_min) { + __free_page(page); + page = reclaim_page(z); + } + + if (page) { + while (z->free_pages < z->pages_low) { + struct page *extra = reclaim_page(z); + if (!extra) + break; + __free_page(extra); + } + } + + /* let kreclaimd handle up to pages_high */ + } + /* If that fails, fall back to rmqueue, but never let + * free_pages go below pages_min... + */ + if (!page && z->free_pages >= z->pages_min) page = rmqueue(z, order); if (page) return page; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/