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From: Ojaswin Mujoo <ojaswin@linux.ibm.com>
To: linux-ext4@vger.kernel.org, "Theodore Ts'o" <tytso@mit.edu>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jan Kara <jack@suse.cz>, Kemeng Shi <shikemeng@huaweicloud.com>,
	Ritesh Harjani <ritesh.list@gmail.com>
Subject: [PATCH v2 08/12] ext4: Don't skip prefetching BLOCK_UNINIT groups
Date: Tue, 30 May 2023 18:03:46 +0530	[thread overview]
Message-ID: <dc3130b8daf45ffe63d8a3c1edcf00eb8ba70e1f.1685449706.git.ojaswin@linux.ibm.com> (raw)
In-Reply-To: <cover.1685449706.git.ojaswin@linux.ibm.com>

Currently, ext4_mb_prefetch() and ext4_mb_prefetch_fini() skip
BLOCK_UNINIT groups since fetching their bitmaps doesn't need disk IO.
As a consequence, we end not initializing the buddy structures and CR0/1
lists for these BGs, even though it can be done without any disk IO
overhead. Hence, don't skip such BGs during prefetch and prefetch_fini.

This improves the accuracy of CR0/1 allocation as earlier, we could have
essentially empty BLOCK_UNINIT groups being ignored by CR0/1 due to their buddy
not being initialized, leading to slower CR2 allocations. With this patch CR0/1
will be able to discover these groups as well, thus improving performance.

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/mballoc.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c86565606359..79455c7e645b 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2590,9 +2590,7 @@ ext4_group_t ext4_mb_prefetch(struct super_block *sb, ext4_group_t group,
 		 */
 		if (gdp && grp && !EXT4_MB_GRP_TEST_AND_SET_READ(grp) &&
 		    EXT4_MB_GRP_NEED_INIT(grp) &&
-		    ext4_free_group_clusters(sb, gdp) > 0 &&
-		    !(ext4_has_group_desc_csum(sb) &&
-		      (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))) {
+		    ext4_free_group_clusters(sb, gdp) > 0 ) {
 			bh = ext4_read_block_bitmap_nowait(sb, group, true);
 			if (bh && !IS_ERR(bh)) {
 				if (!buffer_uptodate(bh) && cnt)
@@ -2633,9 +2631,7 @@ void ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group,
 		grp = ext4_get_group_info(sb, group);
 
 		if (grp && gdp && EXT4_MB_GRP_NEED_INIT(grp) &&
-		    ext4_free_group_clusters(sb, gdp) > 0 &&
-		    !(ext4_has_group_desc_csum(sb) &&
-		      (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))) {
+		    ext4_free_group_clusters(sb, gdp) > 0) {
 			if (ext4_mb_init_group(sb, group, GFP_NOFS))
 				break;
 		}
-- 
2.31.1


  parent reply	other threads:[~2023-05-30 12:37 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-30 12:33 [PATCH v2 00/12] multiblock allocator improvements Ojaswin Mujoo
2023-05-30 12:33 ` [PATCH v2 01/12] Revert "ext4: remove ac->ac_found > sbi->s_mb_min_to_scan dead check in ext4_mb_check_limits" Ojaswin Mujoo
2023-05-30 16:28   ` Sedat Dilek
2023-05-31  8:57     ` Ojaswin Mujoo
2023-06-02 13:45       ` Thorsten Leemhuis
2023-06-02 16:45         ` Theodore Ts'o
2023-05-30 12:33 ` [PATCH v2 02/12] ext4: mballoc: Remove useless setting of ac_criteria Ojaswin Mujoo
2023-05-30 12:33 ` [PATCH v2 03/12] ext4: Remove unused extern variables declaration Ojaswin Mujoo
2023-05-30 12:33 ` [PATCH v2 04/12] ext4: Convert mballoc cr (criteria) to enum Ojaswin Mujoo
2023-06-06 13:13   ` Jan Kara
2023-05-30 12:33 ` [PATCH v2 05/12] ext4: Add per CR extent scanned counter Ojaswin Mujoo
2023-05-30 12:33 ` [PATCH v2 06/12] ext4: Add counter to track successful allocation of goal length Ojaswin Mujoo
2023-05-30 12:33 ` [PATCH v2 07/12] ext4: Avoid scanning smaller extents in BG during CR1 Ojaswin Mujoo
2023-05-30 12:33 ` Ojaswin Mujoo [this message]
2023-05-30 12:33 ` [PATCH v2 09/12] ext4: Ensure ext4_mb_prefetch_fini() is called for all prefetched BGs Ojaswin Mujoo
2023-06-06 14:00   ` Guoqing Jiang
2023-06-27  6:51     ` Ojaswin Mujoo
2023-06-28  1:33       ` Guoqing Jiang
2023-05-30 12:33 ` [PATCH v2 10/12] ext4: Abstract out logic to search average fragment list Ojaswin Mujoo
2023-05-30 12:33 ` [PATCH v2 11/12] ext4: Add allocation criteria 1.5 (CR1_5) Ojaswin Mujoo
2023-06-07 10:21   ` Jan Kara
2023-06-08 14:45     ` Theodore Ts'o
2023-06-09 10:57       ` Ojaswin Mujoo
2023-05-30 12:33 ` [PATCH v2 12/12] ext4: Give symbolic names to mballoc criterias Ojaswin Mujoo
2023-06-07 10:39   ` Jan Kara
2023-06-09  3:14 ` [PATCH v2 00/12] multiblock allocator improvements Theodore Ts'o

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