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ext4: mark several more functions in mballoc.c as noinline

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Ted noticed a stack-deep callchain through
writepages->ext4_mb_regular_allocator->ext4_mb_init_cache->submit_bh ...

With all the static functions in mballoc.c, gcc helpfully
inlines for us, and we get something like this:

ext4_mb_regular_allocator	(232 bytes stack)
	ext4_mb_init_cache	(232 bytes stack)
		submit_bh	(starts 464 deeper)

the 2 ext4 functions here get several others inlined; by telling
gcc not to inline them, we can save stack space for when we
head off into submit_bh land and associated block layer callchains.
The following noinlined functions are only called once, so this
won't impact any other callchains:

ext4_mb_regular_allocator 			(104) (was 232)
	ext4_mb_find_by_goal			 (56) (noinlined)
	ext4_mb_init_group			 (24) (noinlined)
		ext4_mb_init_cache		(136) (was 232)
			ext4_mb_generate_buddy	 (88) (noinlined)
			ext4_mb_generate_from_pa (40) (noinlined)
			submit_bh
	ext4_mb_simple_scan_group		 (24) (noinlined)
	ext4_mb_scan_aligned			 (56) (noinlined)
	ext4_mb_complex_scan_group		 (40) (noinlined)
	ext4_mb_try_best_found			 (24) (noinlined)

now when we head off into submit_bh() we're only 264 bytes deeper
in stack than when we entered ext4_mb_regular_allocator()
(vs. 464 bytes before).  Every 200 bytes helps.  :)

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Eric Sandeen 2009-07-05 22:17:31 -04:00 committed by Theodore Ts'o
parent f4a01017d6
commit 089ceecc1e
1 changed files with 16 additions and 8 deletions
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24
fs/ext4/mballoc.c
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@ -657,7 +657,8 @@ static void ext4_mb_mark_free_simple(struct super_block *sb,
}
}
static void ext4_mb_generate_buddy(struct super_block *sb,
static noinline_for_stack
void ext4_mb_generate_buddy(struct super_block *sb,
void *buddy, void *bitmap, ext4_group_t group)
{
struct ext4_group_info *grp = ext4_get_group_info(sb, group);
@ -1480,7 +1481,8 @@ static void ext4_mb_measure_extent(struct ext4_allocation_context *ac,
ext4_mb_check_limits(ac, e4b, 0);
}
static int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
static noinline_for_stack
int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct ext4_free_extent ex = ac->ac_b_ex;
@ -1507,7 +1509,8 @@ static int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
return 0;
}
static int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
static noinline_for_stack
int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
ext4_group_t group = ac->ac_g_ex.fe_group;
@ -1566,7 +1569,8 @@ static int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
* The routine scans buddy structures (not bitmap!) from given order
* to max order and tries to find big enough chunk to satisfy the req
*/
static void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
static noinline_for_stack
void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct super_block *sb = ac->ac_sb;
@ -1609,7 +1613,8 @@ static void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
* In order to optimize scanning, caller must pass number of
* free blocks in the group, so the routine can know upper limit.
*/
static void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
static noinline_for_stack
void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct super_block *sb = ac->ac_sb;
@ -1668,7 +1673,8 @@ static void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
* we try to find stripe-aligned chunks for stripe-size requests
* XXX should do so at least for multiples of stripe size as well
*/
static void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
static noinline_for_stack
void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct super_block *sb = ac->ac_sb;
@ -1831,7 +1837,8 @@ void ext4_mb_put_buddy_cache_lock(struct super_block *sb,
}
static int ext4_mb_init_group(struct super_block *sb, ext4_group_t group)
static noinline_for_stack
int ext4_mb_init_group(struct super_block *sb, ext4_group_t group)
{
int ret;
@ -3457,7 +3464,8 @@ static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
* used in in-core bitmap. buddy must be generated from this bitmap
* Need to be called with ext4 group lock held
*/
static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
static noinline_for_stack
void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
ext4_group_t group)
{
struct ext4_group_info *grp = ext4_get_group_info(sb, group);