LatencyTOP: sync_page description

[Török Edwin]

Hi Arjan,

LatencyTOP says that sync_page is 'Writing a page to disk', however
I see that even when no writes are involved, such as during a
readdir, lseek, etc.
Naming it a write is misleading, as no program is running that is
doing constant writes to the disk. The only program is writing to a
temp dir in /dev/shm.

What would be a better description for sync_page?

Here are some /proc/latency_stats containing sync_page:

125 6937678 210821 sync_page sync_page_killable sync_page_killable
__lock_page_killable wake_bit_function generic_file_aio_read
get_unused_fd_flags path_walk do_sync_read autoremove_wake_function
security_file_permission rw_verify_area
306 5677749 215746 sync_page sync_page_killable sync_page_killable
__lock_page_killable wake_bit_function generic_file_aio_read
do_sync_read autoremove_wake_function security_file_permission
rw_verify_area vfs_read vfs_llseek
21 435657 59966 sync_page sync_page __lock_page wake_bit_function
read_cache_page_async ntfs_readpage read_cache_page map_mft_record
ntfs_read_locked_inode ntfs_alloc_big_inode iget5_locked
ntfs_test_inode
195 2716409 133660 blk_unplug sync_page sync_page __lock_page
wake_bit_function read_cache_page_async ntfs_readpage
read_cache_page map_mft_record ntfs_read_locked_inode
ntfs_alloc_big_inode iget5_locked
28 1881278 181986 add_to_page_cache_lru sync_page sync_page_killable
sync_page_killable __lock_page_killable wake_bit_function
generic_file_aio_read get_unused_fd_flags path_walk do_sync_read
autoremove_wake_function security_file_permission
2 17132 9746 add_to_page_cache_lru sync_page sync_page_killable
sync_page_killable __lock_page_killable wake_bit_function
generic_file_aio_read do_sync_read autoremove_wake_function
security_file_permission rw_verify_area vfs_read
1 70 70 irq_exit sync_page sync_page_killable sync_page_killable
__lock_page_killable wake_bit_function generic_file_aio_read
do_sync_read autoremove_wake_function security_file_permission
rw_verify_area vfs_read
23 306682 114514 blk_unplug sync_page sync_page_killable
sync_page_killable __lock_page_killable wake_bit_function
generic_file_aio_read do_sync_read autoremove_wake_function
security_file_permission rw_verify_area vfs_read
1 153 153 hrtimer_interrupt smp_apic_timer_interrupt sync_page
sync_page_killable sync_page_killable __lock_page_killable
wake_bit_function generic_file_aio_read do_sync_read
autoremove_wake_function cfq_idle_slice_timer security_file_permission

Thanks,
--Edwin
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