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authorYan, Zheng <zheng.z.yan@intel.com>2013-05-03 02:15:52 -0400
committerTheodore Ts'o <tytso@mit.edu>2013-05-03 02:15:52 -0400
commite30b5dca15dea86aa697f9d58ff646294fe80d3d (patch)
tree549d1ff3f8e5ecb9675a2937113aa99e64ef3ea1 /include/trace
parent0d606e2c9fccdd4e67febf1e2da500e1bfe9e045 (diff)
ext4: fix fio regression
We (Linux Kernel Performance project) found a regression introduced by commit: f7fec032aa ext4: track all extent status in extent status tree The commit causes about 20% performance decrease in fio random write test. Profiler shows that rb_next() uses a lot of CPU time. The call stack is: rb_next ext4_es_find_delayed_extent ext4_map_blocks _ext4_get_block ext4_get_block_write __blockdev_direct_IO ext4_direct_IO generic_file_direct_write __generic_file_aio_write ext4_file_write aio_rw_vect_retry aio_run_iocb do_io_submit sys_io_submit system_call_fastpath io_submit td_io_getevents io_u_queued_complete thread_main main __libc_start_main The cause is that ext4_es_find_delayed_extent() doesn't have an upper bound, it keeps searching until a delayed extent is found. When there are a lots of non-delayed entries in the extent state tree, ext4_es_find_delayed_extent() may uses a lot of CPU time. Reported-by: LKP project <lkp@linux.intel.com> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Cc: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'include/trace')
-rw-r--r--include/trace/events/ext4.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index d0e686402df..8ee15b97cd3 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -2139,7 +2139,7 @@ TRACE_EVENT(ext4_es_remove_extent,
__entry->lblk, __entry->len)
);
-TRACE_EVENT(ext4_es_find_delayed_extent_enter,
+TRACE_EVENT(ext4_es_find_delayed_extent_range_enter,
TP_PROTO(struct inode *inode, ext4_lblk_t lblk),
TP_ARGS(inode, lblk),
@@ -2161,7 +2161,7 @@ TRACE_EVENT(ext4_es_find_delayed_extent_enter,
(unsigned long) __entry->ino, __entry->lblk)
);
-TRACE_EVENT(ext4_es_find_delayed_extent_exit,
+TRACE_EVENT(ext4_es_find_delayed_extent_range_exit,
TP_PROTO(struct inode *inode, struct extent_status *es),
TP_ARGS(inode, es),