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| author | Ritesh Harjani <riteshh@linux.ibm.com> | 2020-09-18 10:36:35 +0530 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2020-10-18 10:36:58 -0400 |
| commit | 9faac62d40131521973192e46a82d5066bb42c09 (patch) | |
| tree | aae393faf4ef585b38c70aedc85fd69a2b222ba9 /include/linux/jbd2.h | |
| parent | 7eb90a2d6a4817d73165a2a1addd5ead2fcb74b1 (diff) | |
| download | lwn-9faac62d40131521973192e46a82d5066bb42c09.tar.gz lwn-9faac62d40131521973192e46a82d5066bb42c09.zip | |
ext4: optimize file overwrites
In case if the file already has underlying blocks/extents allocated
then we don't need to start a journal txn and can directly return
the underlying mapping. Currently ext4_iomap_begin() is used by
both DAX & DIO path. We can check if the write request is an
overwrite & then directly return the mapping information.
This could give a significant perf boost for multi-threaded writes
specially random overwrites.
On PPC64 VM with simulated pmem(DAX) device, ~10x perf improvement
could be seen in random writes (overwrite). Also bcoz this optimizes
away the spinlock contention during jbd2 slab cache allocation
(jbd2_journal_handle). On x86 VM, ~2x perf improvement was observed.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/88e795d8a4d5cd22165c7ebe857ba91d68d8813e.1600401668.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'include/linux/jbd2.h')
0 files changed, 0 insertions, 0 deletions