diff options
| author | Ojaswin Mujoo <ojaswin@linux.ibm.com> | 2023-05-30 18:03:49 +0530 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2023-06-26 19:34:56 -0400 |
| commit | 7e170922f06bf46effa7c57f6035fc463d6edc7e (patch) | |
| tree | 60306c92b8d9cbbbc3764edb53662ad9bd38f9e8 /fs/ext4/mballoc.h | |
| parent | 856d865c178b4fbf4c629d5a7d0df9352d123280 (diff) | |
ext4: Add allocation criteria 1.5 (CR1_5)
CR1_5 aims to optimize allocations which can't be satisfied in CR1. The
fact that we couldn't find a group in CR1 suggests that it would be
difficult to find a continuous extent to compleltely satisfy our
allocations. So before falling to the slower CR2, in CR1.5 we
proactively trim the the preallocations so we can find a group with
(free / fragments) big enough. This speeds up our allocation at the
cost of slightly reduced preallocation.
The patch also adds a new sysfs tunable:
* /sys/fs/ext4/<partition>/mb_cr1_5_max_trim_order
This controls how much CR1.5 can trim a request before falling to CR2.
For example, for a request of order 7 and max trim order 2, CR1.5 can
trim this upto order 5.
Suggested-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/150fdf65c8e4cc4dba71e020ce0859bcf636a5ff.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/mballoc.h')
| -rw-r--r-- | fs/ext4/mballoc.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h index acfdc204e15d..bddc0335c261 100644 --- a/fs/ext4/mballoc.h +++ b/fs/ext4/mballoc.h @@ -86,6 +86,13 @@ #define MB_DEFAULT_LINEAR_SCAN_THRESHOLD 16 /* + * The maximum order upto which CR1.5 can trim a particular allocation request. + * Example, if we have an order 7 request and max trim order of 3, CR1.5 can + * trim this upto order 4. + */ +#define MB_DEFAULT_CR1_5_TRIM_ORDER 3 + +/* * Number of valid buddy orders */ #define MB_NUM_ORDERS(sb) ((sb)->s_blocksize_bits + 2) @@ -179,6 +186,12 @@ struct ext4_allocation_context { /* copy of the best found extent taken before preallocation efforts */ struct ext4_free_extent ac_f_ex; + /* + * goal len can change in CR1.5, so save the original len. This is + * used while adjusting the PA window and for accounting. + */ + ext4_grpblk_t ac_orig_goal_len; + __u32 ac_groups_considered; __u32 ac_flags; /* allocation hints */ __u16 ac_groups_scanned; |