From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, linux-hyperv@vger.kernel.org,
xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@redhat.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Wei Yang <richard.weiyang@linux.alibaba.com>,
Oscar Salvador <osalvador@suse.de>,
Mike Rapoport <rppt@kernel.org>,
Scott Cheloha <cheloha@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>
Subject: [PATCH RFC 2/4] mm/page_alloc: place pages to tail in __putback_isolated_page()
Date: Wed, 16 Sep 2020 20:34:09 +0200 [thread overview]
Message-ID: <20200916183411.64756-3-david@redhat.com> (raw)
In-Reply-To: <20200916183411.64756-1-david@redhat.com>
__putback_isolated_page() already documents that pages will be placed to
the tail of the freelist - this is, however, not the case for
"order >= MAX_ORDER - 2" (see buddy_merge_likely()) - which should be
the case for all existing users.
This change affects two users:
- free page reporting
- page isolation, when undoing the isolation.
This behavior is desireable for pages that haven't really been touched
lately, so exactly the two users that don't actually read/write page
content, but rather move untouched pages.
The new behavior is especially desirable for memory onlining, where we
allow allocation of newly onlined pages via undo_isolate_page_range()
in online_pages(). Right now, we always place them to the head of the
free list, resulting in undesireable behavior: Assume we add
individual memory chunks via add_memory() and online them right away to
the NORMAL zone. We create a dependency chain of unmovable allocations
e.g., via the memmap. The memmap of the next chunk will be placed onto
previous chunks - if the last block cannot get offlined+removed, all
dependent ones cannot get offlined+removed. While this can already be
observed with individual DIMMs, it's more of an issue for virtio-mem
(and I suspect also ppc DLPAR).
Note: If we observe a degradation due to the changed page isolation
behavior (which I doubt), we can always make this configurable by the
instance triggering undo of isolation (e.g., alloc_contig_range(),
memory onlining, memory offlining).
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/page_alloc.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 91cefb8157dd..bba9a0f60c70 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -89,6 +89,12 @@ typedef int __bitwise fop_t;
*/
#define FOP_SKIP_REPORT_NOTIFY ((__force fop_t)BIT(0))
+/*
+ * Place the freed page to the tail of the freelist after buddy merging. Will
+ * get ignored with page shuffling enabled.
+ */
+#define FOP_TO_TAIL ((__force fop_t)BIT(1))
+
/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
static DEFINE_MUTEX(pcp_batch_high_lock);
#define MIN_PERCPU_PAGELIST_FRACTION (8)
@@ -1040,6 +1046,8 @@ static inline void __free_one_page(struct page *page, unsigned long pfn,
if (is_shuffle_order(order))
to_tail = shuffle_pick_tail();
+ else if (fop_flags & FOP_TO_TAIL)
+ to_tail = true;
else
to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
@@ -3289,7 +3297,7 @@ void __putback_isolated_page(struct page *page, unsigned int order, int mt)
/* Return isolated page to tail of freelist. */
__free_one_page(page, page_to_pfn(page), zone, order, mt,
- FOP_SKIP_REPORT_NOTIFY);
+ FOP_SKIP_REPORT_NOTIFY | FOP_TO_TAIL);
}
/*
--
2.26.2
next prev parent reply other threads:[~2020-09-16 18:35 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 18:34 [PATCH RFC 0/4] mm: place pages to the freelist tail when onling and undoing isolation David Hildenbrand
2020-09-16 18:34 ` [PATCH RFC 1/4] mm/page_alloc: convert "report" flag of __free_one_page() to a proper flag David Hildenbrand
2020-09-16 21:44 ` Alexander Duyck
2020-09-18 1:53 ` Wei Yang
2020-09-18 7:23 ` David Hildenbrand
2020-09-24 10:19 ` Vlastimil Babka
2020-09-25 10:34 ` Oscar Salvador
2020-09-16 18:34 ` David Hildenbrand [this message]
2020-09-16 21:50 ` [PATCH RFC 2/4] mm/page_alloc: place pages to tail in __putback_isolated_page() Alexander Duyck
2020-09-18 2:07 ` Wei Yang
2020-09-18 7:27 ` David Hildenbrand
2020-09-21 1:57 ` Wei Yang
2020-09-18 2:16 ` Wei Yang
2020-09-18 7:29 ` David Hildenbrand
2020-09-24 10:37 ` Vlastimil Babka
2020-09-25 8:10 ` David Hildenbrand
2020-09-25 13:19 ` Oscar Salvador
2020-09-25 13:30 ` David Hildenbrand
2020-09-16 18:34 ` [PATCH RFC 3/4] mm/page_alloc: always move pages to the tail of the freelist in unset_migratetype_isolate() David Hildenbrand
2020-09-18 2:29 ` Wei Yang
2020-09-18 7:30 ` David Hildenbrand
2020-09-24 11:13 ` Vlastimil Babka
2020-09-25 2:45 ` Wei Yang
2020-09-25 8:05 ` David Hildenbrand
2020-09-25 8:39 ` Vlastimil Babka
2020-09-25 13:13 ` David Hildenbrand
2020-09-25 13:57 ` Oscar Salvador
2020-09-16 18:34 ` [PATCH RFC 4/4] mm/page_alloc: place pages to tail in __free_pages_core() David Hildenbrand
2020-09-24 13:44 ` Vlastimil Babka
2020-09-28 7:58 ` Oscar Salvador
2020-09-28 8:36 ` David Hildenbrand
2020-09-28 12:53 ` Oscar Salvador
2020-09-16 18:50 ` [PATCH RFC 0/4] mm: place pages to the freelist tail when onling and undoing isolation osalvador
2020-09-16 19:31 ` David Hildenbrand
2020-09-18 2:30 ` Wei Yang
2020-09-18 7:32 ` David Hildenbrand
2020-09-23 14:31 ` Vlastimil Babka
2020-09-23 15:26 ` David Hildenbrand
2020-09-24 9:40 ` Mel Gorman
2020-09-24 9:54 ` David Hildenbrand
2020-09-24 13:59 ` Vlastimil Babka
2020-09-24 14:29 ` David Hildenbrand
2020-09-24 1:57 ` Wei Yang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200916183411.64756-3-david@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=alexander.h.duyck@linux.intel.com \
--cc=cheloha@linux.ibm.com \
--cc=dave.hansen@intel.com \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@kernel.org \
--cc=mpe@ellerman.id.au \
--cc=osalvador@suse.de \
--cc=richard.weiyang@linux.alibaba.com \
--cc=rppt@kernel.org \
--cc=vbabka@suse.cz \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).