From: Vlastimil Babka <vbabka@suse.cz> To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Hugh Dickins <hughd@google.com>, Andrea Arcangeli <aarcange@redhat.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@suse.cz>, Alex Thorlton <athorlton@sgi.com>, David Rientjes <rientjes@google.com>, Vlastimil Babka <vbabka@suse.cz> Subject: [RFC 4/4] mm, thp: wake up khugepaged when huge page is not available Date: Mon, 11 May 2015 16:35:40 +0200 [thread overview] Message-ID: <1431354940-30740-5-git-send-email-vbabka@suse.cz> (raw) In-Reply-To: <1431354940-30740-1-git-send-email-vbabka@suse.cz> After previous patch, THP page faults check the thp_avail_nodes nodemask to determine whether to attempt allocating hugepage or fallback immediately. The khugepaged task is responsible for attempting reclaim and compaction for nodes where hugepages are not available, and updating the nodemask as appropriate. To get faster reaction on THP allocation failures, we will wake up khugepaged whenever THP page fault has to fallback. This includes both situations when hugepage was supposed to be available, but allocation fails, and situations where hugepage is already marked as unavailable. In the latter case, khugepaged will not wait according to its alloc_sleep_millisecs parameter under /sys, but retry allocation immediately. This is done to scale the khugepaged activity with respect to THP demand, instead of a fixed tunable. Excessive compaction failures are still being prevented by the self-tuning deferred compaction mechanism in this case. For this mechanism to work as intended, the check for deferred compaction should be done on each THP allocation attempt to bump the internal counter, and waiting full alloc_sleep_millisecs period could make the deferred periods excessively long. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> --- mm/huge_memory.c | 22 ++++++++++++++++++---- mm/internal.h | 5 +---- 2 files changed, 19 insertions(+), 8 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d3081a7..b3d08a0 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -104,6 +104,15 @@ static struct khugepaged_scan khugepaged_scan = { }; nodemask_t thp_avail_nodes = NODE_MASK_ALL; +static bool khugepaged_thp_requested = false; + +void thp_avail_clear(int nid) +{ + node_clear(nid, thp_avail_nodes); + khugepaged_thp_requested = true; + wake_up_interruptible(&khugepaged_wait); +} + static int set_recommended_min_free_kbytes(void) { @@ -2263,7 +2272,8 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, static void khugepaged_alloc_sleep(void) { - wait_event_freezable_timeout(khugepaged_wait, false, + wait_event_freezable_timeout(khugepaged_wait, + khugepaged_thp_requested, msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); } @@ -2381,6 +2391,8 @@ static bool khugepaged_check_nodes(struct page **hpage) struct page *newpage = NULL; gfp_t gfp = alloc_hugepage_gfpmask(khugepaged_defrag()); + khugepaged_thp_requested = false; + for_each_online_node(nid) { if (node_isset(nid, thp_avail_nodes)) { ret = true; @@ -2780,13 +2792,15 @@ breakouterloop_mmap_sem: static int khugepaged_has_work(void) { - return !list_empty(&khugepaged_scan.mm_head) && + return (khugepaged_thp_requested || + !list_empty(&khugepaged_scan.mm_head)) && khugepaged_enabled(); } static int khugepaged_wait_event(void) { - return !list_empty(&khugepaged_scan.mm_head) || + return khugepaged_thp_requested || + !list_empty(&khugepaged_scan.mm_head) || kthread_should_stop(); } @@ -2837,7 +2851,7 @@ static void khugepaged_wait_work(void) return; wait_event_freezable_timeout(khugepaged_wait, - kthread_should_stop(), + khugepaged_thp_requested || kthread_should_stop(), msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); return; } diff --git a/mm/internal.h b/mm/internal.h index 6d9a711..5c37e4d 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -179,10 +179,7 @@ static inline void thp_avail_set(int nid) node_set(nid, thp_avail_nodes); } -static inline void thp_avail_clear(int nid) -{ - node_clear(nid, thp_avail_nodes); -} +extern void thp_avail_clear(int nid); #else -- 2.1.4
WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz> To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Hugh Dickins <hughd@google.com>, Andrea Arcangeli <aarcange@redhat.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@suse.cz>, Alex Thorlton <athorlton@sgi.com>, David Rientjes <rientjes@google.com>, Vlastimil Babka <vbabka@suse.cz> Subject: [RFC 4/4] mm, thp: wake up khugepaged when huge page is not available Date: Mon, 11 May 2015 16:35:40 +0200 [thread overview] Message-ID: <1431354940-30740-5-git-send-email-vbabka@suse.cz> (raw) In-Reply-To: <1431354940-30740-1-git-send-email-vbabka@suse.cz> After previous patch, THP page faults check the thp_avail_nodes nodemask to determine whether to attempt allocating hugepage or fallback immediately. The khugepaged task is responsible for attempting reclaim and compaction for nodes where hugepages are not available, and updating the nodemask as appropriate. To get faster reaction on THP allocation failures, we will wake up khugepaged whenever THP page fault has to fallback. This includes both situations when hugepage was supposed to be available, but allocation fails, and situations where hugepage is already marked as unavailable. In the latter case, khugepaged will not wait according to its alloc_sleep_millisecs parameter under /sys, but retry allocation immediately. This is done to scale the khugepaged activity with respect to THP demand, instead of a fixed tunable. Excessive compaction failures are still being prevented by the self-tuning deferred compaction mechanism in this case. For this mechanism to work as intended, the check for deferred compaction should be done on each THP allocation attempt to bump the internal counter, and waiting full alloc_sleep_millisecs period could make the deferred periods excessively long. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> --- mm/huge_memory.c | 22 ++++++++++++++++++---- mm/internal.h | 5 +---- 2 files changed, 19 insertions(+), 8 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d3081a7..b3d08a0 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -104,6 +104,15 @@ static struct khugepaged_scan khugepaged_scan = { }; nodemask_t thp_avail_nodes = NODE_MASK_ALL; +static bool khugepaged_thp_requested = false; + +void thp_avail_clear(int nid) +{ + node_clear(nid, thp_avail_nodes); + khugepaged_thp_requested = true; + wake_up_interruptible(&khugepaged_wait); +} + static int set_recommended_min_free_kbytes(void) { @@ -2263,7 +2272,8 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, static void khugepaged_alloc_sleep(void) { - wait_event_freezable_timeout(khugepaged_wait, false, + wait_event_freezable_timeout(khugepaged_wait, + khugepaged_thp_requested, msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); } @@ -2381,6 +2391,8 @@ static bool khugepaged_check_nodes(struct page **hpage) struct page *newpage = NULL; gfp_t gfp = alloc_hugepage_gfpmask(khugepaged_defrag()); + khugepaged_thp_requested = false; + for_each_online_node(nid) { if (node_isset(nid, thp_avail_nodes)) { ret = true; @@ -2780,13 +2792,15 @@ breakouterloop_mmap_sem: static int khugepaged_has_work(void) { - return !list_empty(&khugepaged_scan.mm_head) && + return (khugepaged_thp_requested || + !list_empty(&khugepaged_scan.mm_head)) && khugepaged_enabled(); } static int khugepaged_wait_event(void) { - return !list_empty(&khugepaged_scan.mm_head) || + return khugepaged_thp_requested || + !list_empty(&khugepaged_scan.mm_head) || kthread_should_stop(); } @@ -2837,7 +2851,7 @@ static void khugepaged_wait_work(void) return; wait_event_freezable_timeout(khugepaged_wait, - kthread_should_stop(), + khugepaged_thp_requested || kthread_should_stop(), msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); return; } diff --git a/mm/internal.h b/mm/internal.h index 6d9a711..5c37e4d 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -179,10 +179,7 @@ static inline void thp_avail_set(int nid) node_set(nid, thp_avail_nodes); } -static inline void thp_avail_clear(int nid) -{ - node_clear(nid, thp_avail_nodes); -} +extern void thp_avail_clear(int nid); #else -- 2.1.4 -- 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/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2015-05-11 14:36 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-05-11 14:35 [RFC 0/4] Outsourcing page fault THP allocations to khugepaged Vlastimil Babka 2015-05-11 14:35 ` Vlastimil Babka 2015-05-11 14:35 ` [RFC 1/4] mm, thp: stop preallocating hugepages in khugepaged Vlastimil Babka 2015-05-11 14:35 ` Vlastimil Babka 2015-06-18 0:34 ` David Rientjes 2015-06-18 0:34 ` David Rientjes 2015-05-11 14:35 ` [RFC 2/4] mm, thp: khugepaged checks for THP allocability before scanning Vlastimil Babka 2015-05-11 14:35 ` Vlastimil Babka 2015-06-18 1:00 ` David Rientjes 2015-06-18 1:00 ` David Rientjes 2015-06-23 15:41 ` Vlastimil Babka 2015-06-23 15:41 ` Vlastimil Babka 2015-05-11 14:35 ` [RFC 3/4] mm, thp: try fault allocations only if we expect them to succeed Vlastimil Babka 2015-05-11 14:35 ` Vlastimil Babka 2015-06-18 1:20 ` David Rientjes 2015-06-18 1:20 ` David Rientjes 2015-06-23 16:23 ` Vlastimil Babka 2015-05-11 14:35 ` Vlastimil Babka [this message] 2015-05-11 14:35 ` [RFC 4/4] mm, thp: wake up khugepaged when huge page is not available Vlastimil Babka
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