linux-kernel - [PATCH 6/6] mm: compaction: skip fast freepages isolation if enough freepages are isolated

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <f39c2c07f2dba2732fd9c0843572e5bef96f7f67.1685018752.git.baolin.wang@linux.alibaba.com>
Date:   Thu, 25 May 2023 20:54:01 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     akpm@...ux-foundation.org
Cc:     mgorman@...hsingularity.net, vbabka@...e.cz,
        baolin.wang@...ux.alibaba.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 6/6] mm: compaction: skip fast freepages isolation if enough freepages are isolated

I've observed that fast isolation often isolates more pages than
cc->migratepages, and the excess freepages will be released back to the
buddy system. So skip fast freepages isolation if enough freepages are
isolated to save some CPU cycles.

Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
 mm/compaction.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/compaction.c b/mm/compaction.c
index eccec84dae82..3ade4c095ed2 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1550,6 +1550,10 @@ static void fast_isolate_freepages(struct compact_control *cc)
 
 		spin_unlock_irqrestore(&cc->zone->lock, flags);
 
+		/* Skip fast search if enough freepages isolated */
+		if (cc->nr_freepages >= cc->nr_migratepages)
+			break;
+
 		/*
 		 * Smaller scan on next order so the total scan is related
 		 * to freelist_scan_limit.
-- 
2.27.0