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libext2fs: allow the default journal size to go as large as a gigabyte 

Recent research has shown that for a metadata-heavy workload, a 128 MB
is journal be a bottleneck on HDD's, and that the optimal journal size
is proportional to number of unique metadata blocks that can be
modified (and written into the journal) in a 30 second window.  One
gigabyte should be sufficient for most workloads, which will be used
for file systems larger than 128 gigabytes.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
next
Theodore Ts'o 2016-09-01 11:37:59 -04:00
parent 35a4e1b1c5
commit bbd2f78cf6
3 changed files with 21 additions and 13 deletions
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26
lib/ext2fs/mkjournal.c
View File

@ -334,20 +334,28 @@ out2:
* Find a reasonable journal file size (in blocks) given the number of blocks
* in the filesystem. For very small filesystems, it is not reasonable to
* have a journal that fills more than half of the filesystem.
*
* n.b. comments assume 4k blocks
*/
int ext2fs_default_journal_size(__u64 num_blocks)
{
if (num_blocks < 2048)
return -1;
if (num_blocks < 32768)
return (1024);
if (num_blocks < 256*1024)
return (4096);
if (num_blocks < 512*1024)
return (8192);
if (num_blocks < 1024*1024)
return (16384);
return 32768;
if (num_blocks < 32768) /* 128 MB */
return (1024); /* 4 MB */
if (num_blocks < 256*1024) /* 1 GB */
return (4096); /* 16 MB */
if (num_blocks < 512*1024) /* 2 GB */
return (8192); /* 32 MB */
if (num_blocks < 4096*1024) /* 16 GB */
return (16384); /* 64 MB */
if (num_blocks < 8192*1024) /* 32 GB */
return (32768); /* 128 MB */
if (num_blocks < 16384*1024) /* 64 GB */
return (65536); /* 256 MB */
if (num_blocks < 32768*1024) /* 128 GB */
return (131072); /* 512 MB */
return 262144; /* 1 GB */
}
int ext2fs_journal_sb_start(int blocksize)

4
tests/d_dumpe2fs_group_only/expect
View File

@ -4,7 +4,7 @@ Superblock backups stored on blocks:
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
Pass 1: Checking inodes, blocks, and sizes
@ -12,7 +12,7 @@ Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
test_filesys: 11/262144 files (0.0% non-contiguous), 51278/1048576 blocks
test_filesys: 11/262144 files (0.0% non-contiguous), 34894/1048576 blocks
Exit status is 0
dumpe2fs output

4
tests/t_uninit_bg_rm/expect
View File

@ -7,7 +7,7 @@ Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
test_filesys: 11/65536 files (0.0% non-contiguous), 52294/1048576 blocks
test_filesys: 11/65536 files (0.0% non-contiguous), 35910/1048576 blocks
mke2fs -q -t ext4 -O bigalloc -F -o Linux -b 1024 -C 8192 test.img 10G
tune2fs -f -O ^uninit_bg test.img
@ -18,4 +18,4 @@ Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
test_filesys: 11/655360 files (0.0% non-contiguous), 199864/10485760 blocks
test_filesys: 11/655360 files (0.0% non-contiguous), 232632/10485760 blocks