linux-kernel - [PATCH 1 of 3] slob: fix free block merging at head of subpage

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Message-Id: <771a5ab2c6b7347df5d7.1200592639@cinder.waste.org>
Date:	Thu, 17 Jan 2008 11:57:19 -0600
From:	Matt Mackall <mpm@...enic.com>
To:	Andrew Morton <apkm@...ux-foundation.com>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 1 of 3] slob: fix free block merging at head of subpage

We weren't merging freed blocks at the beginning of the free list.
Fixing this showed a 2.5% efficiency improvement in a userspace test
harness.

Signed-off-by: Matt Mackall <mpm@...enic.com>

diff -r 408d4beddb6c -r 771a5ab2c6b7 mm/slob.c
--- a/mm/slob.c	Wed Jan 16 19:00:27 2008 +0000
+++ b/mm/slob.c	Wed Jan 16 18:14:29 2008 -0600
@@ -398,6 +398,10 @@
 	sp->units += units;
 
 	if (b < sp->free) {
+		if (b + units == sp->free) {
+			units += slob_units(sp->free);
+			sp->free = slob_next(sp->free);
+		}
 		set_slob(b, units, sp->free);
 		sp->free = b;
 	} else {
--
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