From: David Sterba <dsterba@suse.com>
To: linux-btrfs@vger.kernel.org
Cc: David Sterba <dsterba@suse.com>
Subject: [PATCH 6/9] btrfs: reduce compressed_bio members' types
Date: Tue, 25 May 2021 19:08:36 +0200 [thread overview]
Message-ID: <1a3c6cddd909d922948a22ac1f287293e0deb665.1621961965.git.dsterba@suse.com> (raw)
In-Reply-To: <cover.1621961965.git.dsterba@suse.com>
Several members of compressed_bio are of type that's unnecessarily big
for the values that they'd hold:
- the size of the uncompressed and compressed data is 128K now, we can
keep is as int
- same for number of pages
- the compress type fits to a byte
- the errors is 0/1
The size of the unpatched structure is 80 bytes with several holes.
Reordering nr_pages next to the pages the hole after pending_bios is
filled and the resulting size is 56 bytes. This keeps the csums array
aligned to 8 bytes, which is nice. Further size optimizations may be
possible but right now it looks good to me:
struct compressed_bio {
refcount_t pending_bios; /* 0 4 */
unsigned int nr_pages; /* 4 4 */
struct page * * compressed_pages; /* 8 8 */
struct inode * inode; /* 16 8 */
u64 start; /* 24 8 */
unsigned int len; /* 32 4 */
unsigned int compressed_len; /* 36 4 */
u8 compress_type; /* 40 1 */
u8 errors; /* 41 1 */
/* XXX 2 bytes hole, try to pack */
int mirror_num; /* 44 4 */
struct bio * orig_bio; /* 48 8 */
u8 sums[]; /* 56 0 */
/* size: 56, cachelines: 1, members: 12 */
/* sum members: 54, holes: 1, sum holes: 2 */
/* last cacheline: 56 bytes */
};
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/compression.c | 2 +-
fs/btrfs/compression.h | 20 ++++++++++----------
2 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 9a0c26e4e389..c006f5d81c2a 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -507,7 +507,7 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
}
if (bytes_left < PAGE_SIZE) {
btrfs_info(fs_info,
- "bytes left %lu compress len %lu nr %lu",
+ "bytes left %lu compress len %u nr %u",
bytes_left, cb->compressed_len, cb->nr_pages);
}
bytes_left -= PAGE_SIZE;
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 8001b700ea3a..00d8439048c9 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -31,6 +31,9 @@ struct compressed_bio {
/* number of bios pending for this compressed extent */
refcount_t pending_bios;
+ /* Number of compressed pages in the array */
+ unsigned int nr_pages;
+
/* the pages with the compressed data on them */
struct page **compressed_pages;
@@ -40,20 +43,17 @@ struct compressed_bio {
/* starting offset in the inode for our pages */
u64 start;
- /* number of bytes in the inode we're working on */
- unsigned long len;
-
- /* number of bytes on disk */
- unsigned long compressed_len;
+ /* Number of bytes in the inode we're working on */
+ unsigned int len;
- /* the compression algorithm for this bio */
- int compress_type;
+ /* Number of bytes on disk */
+ unsigned int compressed_len;
- /* number of compressed pages in the array */
- unsigned long nr_pages;
+ /* The compression algorithm for this bio */
+ u8 compress_type;
/* IO errors */
- int errors;
+ u8 errors;
int mirror_num;
/* for reads, this is the bio we are copying the data into */
--
2.29.2
next prev parent reply other threads:[~2021-05-25 17:11 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-25 17:08 [PATCH 0/9] Misc fixups and cleanups David Sterba
2021-05-25 17:08 ` [PATCH 1/9] btrfs: sysfs: fix format string for some discard stats David Sterba
2021-05-25 23:47 ` Qu Wenruo
2021-05-26 6:01 ` Anand Jain
2021-05-25 17:08 ` [PATCH 2/9] btrfs: clear defrag status of a root if starting transaction fails David Sterba
2021-05-25 23:49 ` Qu Wenruo
2021-05-26 6:05 ` Anand Jain
2021-05-25 17:08 ` [PATCH 3/9] btrfs: clear log tree recovering status " David Sterba
2021-05-25 23:50 ` Qu Wenruo
2021-05-26 6:57 ` Anand Jain
2021-05-25 17:08 ` [PATCH 4/9] btrfs: scrub: factor out common scrub_stripe constraints David Sterba
2021-05-25 23:51 ` Qu Wenruo
2021-05-26 7:16 ` Anand Jain
2021-05-25 17:08 ` [PATCH 5/9] btrfs: document byte swap optimization of root_item::flags accessors David Sterba
2021-05-26 7:28 ` Anand Jain
2021-05-25 17:08 ` David Sterba [this message]
2021-05-26 8:40 ` [PATCH] btrfs: optimize users of members of the struct compressed_bio Anand Jain
2021-05-26 16:34 ` David Sterba
2021-05-26 8:41 ` [PATCH 6/9] btrfs: reduce compressed_bio members' types Anand Jain
2021-05-25 17:08 ` [PATCH 7/9] btrfs: remove extra sb::s_id from message in btrfs_validate_metadata_buffer David Sterba
2021-05-25 23:59 ` Qu Wenruo
2021-05-26 12:54 ` Anand Jain
2021-05-25 17:08 ` [PATCH 8/9] btrfs: simplify eb checksum verification " David Sterba
2021-05-26 0:05 ` Qu Wenruo
2021-05-26 16:31 ` David Sterba
2021-05-26 16:58 ` David Sterba
2021-05-26 23:13 ` Qu Wenruo
2021-05-26 23:13 ` David Sterba
2021-05-25 17:08 ` [PATCH 9/9] btrfs: clean up header members offsets in write helpers David Sterba
2021-05-26 0:07 ` Qu Wenruo
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