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authorJan Kara <jack@suse.cz>2019-12-18 18:44:33 +0100
committerTheodore Ts'o <tytso@mit.edu>2019-12-26 11:57:18 -0500
commit8cd115bdda17751ee2adab614a80df72228b3809 (patch)
treecf216cc2c9faab3d704e65595ce486225cf8edd0 /fs/ext4/file.c
parent4549b49f82ab40c214778f316b6898aa4132723a (diff)
ext4: Optimize ext4 DIO overwrites
Currently we start transaction for mapping every extent for writing using direct IO. This is unnecessary when we know we are overwriting already allocated blocks and the overhead of starting a transaction can be significant especially for multithreaded workloads doing small writes. Use iomap operations that avoid starting a transaction for direct IO overwrites. This improves throughput of 4k random writes - fio jobfile: [global] rw=randrw norandommap=1 invalidate=0 bs=4k numjobs=16 time_based=1 ramp_time=30 runtime=120 group_reporting=1 ioengine=psync direct=1 size=16G filename=file1.0.0:file1.0.1:file1.0.2:file1.0.3:file1.0.4:file1.0.5:file1.0.6:file1.0.7:file1.0.8:file1.0.9:file1.0.10:file1.0.11:file1.0.12:file1.0.13:file1.0.14:file1.0.15:file1.0.16:file1.0.17:file1.0.18:file1.0.19:file1.0.20:file1.0.21:file1.0.22:file1.0.23:file1.0.24:file1.0.25:file1.0.26:file1.0.27:file1.0.28:file1.0.29:file1.0.30:file1.0.31 file_service_type=random nrfiles=32 from 3018MB/s to 4059MB/s in my test VM running test against simulated pmem device (note that before iomap conversion, this workload was able to achieve 3708MB/s because old direct IO path avoided transaction start for overwrites as well). For dax, the win is even larger improving throughput from 3042MB/s to 4311MB/s. Reported-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20191218174433.19380-1-jack@suse.cz Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/file.c')
-rw-r--r--fs/ext4/file.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 9c2711bce0f9..5f225881176b 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -447,6 +447,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
struct inode *inode = file_inode(iocb->ki_filp);
loff_t offset = iocb->ki_pos;
size_t count = iov_iter_count(from);
+ const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
bool extend = false, unaligned_io = false;
bool ilock_shared = true;
@@ -526,7 +527,9 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
ext4_journal_stop(handle);
}
- ret = iomap_dio_rw(iocb, from, &ext4_iomap_ops, &ext4_dio_write_ops,
+ if (ilock_shared)
+ iomap_ops = &ext4_iomap_overwrite_ops;
+ ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
is_sync_kiocb(iocb) || unaligned_io || extend);
if (extend)