From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 01/11] mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations Date: Mon, 13 Jan 2020 16:29:04 -0800 Message-ID: <20200114002904.h9bSo%akpm__21904.1851743654$1578961831$gmane$org@linux-foundation.org> References: <20200113162831.f7d69e11e9e673c40005c9b0@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:44818 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726536AbgANA3F (ORCPT ); Mon, 13 Jan 2020 19:29:05 -0500 In-Reply-To: <20200113162831.f7d69e11e9e673c40005c9b0@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: rientjes@google.com, mhocko@suse.com, mgorman@suse.de, kirill@shutemov.name, aarcange@redhat.com, vbabka@suse.cz, akpm@linux-foundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org From: Vlastimil Babka Subject: mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations THP page faults now attempt a __GFP_THISNODE allocation first, which should only compact existing free memory, followed by another attempt that can allocate from any node using reclaim/compaction effort specified by global defrag setting and madvise. This patch makes the following changes to the scheme: - before the patch, the first allocation relies on a check for pageblock order and __GFP_IO to prevent excessive reclaim. This however affects also the second attempt, which is not limited to single node. Instead of that, reuse the existing check for costly order __GFP_NORETRY allocations, and make sure the first THP attempt uses __GFP_NORETRY. As a side-effect, all costly order __GFP_NORETRY allocations will bail out if compaction needs reclaim, while previously they only bailed out when compaction was deferred due to previous failures. This should be still acceptable within the __GFP_NORETRY semantics. - before the patch, the second allocation attempt (on all nodes) was passing __GFP_NORETRY. This is redundant as the check for pageblock order (discussed above) was stronger. It's also contrary to madvise(MADV_HUGEPAGE) which means some effort to allocate THP is requested. After this patch, the second attempt doesn't pass __GFP_THISNODE nor __GFP_NORETRY. To sum up, THP page faults now try the following attempts: 1. local node only THP allocation with no reclaim, just compaction. 2. for madvised VMA's or when synchronous compaction is enabled always - THP allocation from any node with effort determined by global defrag setting and VMA madvise 3. fallback to base pages on any node Link: http://lkml.kernel.org/r/08a3f4dd-c3ce-0009-86c5-9ee51aba8557@suse.cz Fixes: b39d0ee2632d ("mm, page_alloc: avoid expensive reclaim when compaction may not succeed") Signed-off-by: Vlastimil Babka Acked-by: Michal Hocko Cc: Linus Torvalds Cc: Andrea Arcangeli Cc: Mel Gorman Cc: "Kirill A. Shutemov" Cc: David Rientjes Signed-off-by: Andrew Morton --- mm/mempolicy.c | 10 +++++++--- mm/page_alloc.c | 24 +++++------------------- 2 files changed, 12 insertions(+), 22 deletions(-) --- a/mm/mempolicy.c~mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations +++ a/mm/mempolicy.c @@ -2148,18 +2148,22 @@ alloc_pages_vma(gfp_t gfp, int order, st nmask = policy_nodemask(gfp, pol); if (!nmask || node_isset(hpage_node, *nmask)) { mpol_cond_put(pol); + /* + * First, try to allocate THP only on local node, but + * don't reclaim unnecessarily, just compact. + */ page = __alloc_pages_node(hpage_node, - gfp | __GFP_THISNODE, order); + gfp | __GFP_THISNODE | __GFP_NORETRY, order); /* * If hugepage allocations are configured to always * synchronous compact or the vma has been madvised * to prefer hugepage backing, retry allowing remote - * memory as well. + * memory with both reclaim and compact as well. */ if (!page && (gfp & __GFP_DIRECT_RECLAIM)) page = __alloc_pages_node(hpage_node, - gfp | __GFP_NORETRY, order); + gfp, order); goto out; } --- a/mm/page_alloc.c~mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations +++ a/mm/page_alloc.c @@ -4476,8 +4476,11 @@ retry_cpuset: if (page) goto got_pg; - if (order >= pageblock_order && (gfp_mask & __GFP_IO) && - !(gfp_mask & __GFP_RETRY_MAYFAIL)) { + /* + * Checks for costly allocations with __GFP_NORETRY, which + * includes some THP page fault allocations + */ + if (costly_order && (gfp_mask & __GFP_NORETRY)) { /* * If allocating entire pageblock(s) and compaction * failed because all zones are below low watermarks @@ -4498,23 +4501,6 @@ retry_cpuset: if (compact_result == COMPACT_SKIPPED || compact_result == COMPACT_DEFERRED) goto nopage; - }