Re: [LKP] [lkp] [xfs] 68a9f5e700: aim7.jobs-per-min -13.6% regression

Christoph Hellwig
2016-08-14T08:26:21Z

On Sat, Aug 13, 2016 at 02:30:54AM +0200, Christoph Hellwig wrote:
> Below is a patch I hacked up this morning to do just that. It passes
> xfstests, but I've not done any real benchmarking with it. If the
> reduced lookup overhead in it doesn't help enough we'll need to some
> sort of look aside cache for the information, but I hope that we
> can avoid that. And yes, it's a rather large patch - but the old
> path was so entangled that I couldn't come up with something lighter.

Hi Fengguang or Xiaolong,

any chance to add this thread to a lkp run? I've played around with
Dave's simplied xfs_io run, and while the end result for 1k block
size looks pretty similar in terms of execution time and throughput
the profiles look much better. For 512 byte or 1 byte tests the
tests completes a lot faster too.

Here is the perf report output for a 1k block size run, the first
item directly related to the block mapping shows up is
xfs_file_iomap_begin_delay at .75%. Although I'm a bit worried
up up_/down_read showing up so much. While we take a ilock and
iolock a lot they should be mostly uncontended for such a single
threaded write, so the overhead seems a bit worrisome.

(FYI, the tree this was tested on also has the mark_page_accessed
and pagefault_disable fixes applied)

# To display the perf.data header info, please use --header/--header-only options.
#
# Samples: 7K of event 'cpu-clock'
# Event count (approx.): 1909250000
#
# Overhead Command Shared Object Symbol
# ........ ............ ................. .....................................
#
37.71% swapper [kernel.kallsyms] [k] native_safe_halt
9.85% kworker/u8:5 [kernel.kallsyms] [k] __copy_user_nocache
2.83% xfs_io [kernel.kallsyms] [k] copy_user_generic_string
2.33% xfs_io [kernel.kallsyms] [k] __memset
2.23% xfs_io [kernel.kallsyms] [k] __block_commit_write.isra.34
1.73% xfs_io [kernel.kallsyms] [k] down_write
1.64% xfs_io [kernel.kallsyms] [k] up_write
1.39% xfs_io [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
1.23% xfs_io [kernel.kallsyms] [k] entry_SYSCALL_64_fastpath
1.18% xfs_io [kernel.kallsyms] [k] __mark_inode_dirty
1.18% xfs_io [kernel.kallsyms] [k] _raw_spin_lock
1.15% kworker/u8:5 [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
1.13% xfs_io [kernel.kallsyms] [k] __block_write_begin_int
1.10% xfs_io [kernel.kallsyms] [k] mark_buffer_dirty
1.07% xfs_io [kernel.kallsyms] [k] __radix_tree_lookup
1.01% kworker/0:2 [kernel.kallsyms] [k] end_buffer_async_write
0.97% xfs_io [kernel.kallsyms] [k] unlock_page
0.92% kworker/0:2 [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
0.89% xfs_io [kernel.kallsyms] [k] iov_iter_copy_from_user_atomic
0.84% xfs_io [kernel.kallsyms] [k] generic_write_end
0.80% xfs_io [kernel.kallsyms] [k] get_page_from_freelist
0.80% xfs_io [kernel.kallsyms] [k] xfs_perag_put
0.79% xfs_io [kernel.kallsyms] [k] __add_to_page_cache_locked
0.75% xfs_io libc-2.19.so [.] __libc_pwrite
0.72% xfs_io [kernel.kallsyms] [k] xfs_file_iomap_begin_delay.isra.5
0.71% xfs_io [kernel.kallsyms] [k] iomap_write_actor
0.67% xfs_io [kernel.kallsyms] [k] pagecache_get_page
0.64% xfs_io [kernel.kallsyms] [k] balance_dirty_pages_ratelimited
0.64% xfs_io [kernel.kallsyms] [k] vfs_write
0.63% kworker/u8:5 [kernel.kallsyms] [k] clear_page_dirty_for_io
0.62% xfs_io [kernel.kallsyms] [k] xfs_file_write_iter
0.60% xfs_io [kernel.kallsyms] [k] __vfs_write
0.55% xfs_io [kernel.kallsyms] [k] page_waitqueue
0.54% xfs_io [kernel.kallsyms] [k] xfs_perag_get
0.52% xfs_io [kernel.kallsyms] [k] __wake_up_bit
0.52% xfs_io [kernel.kallsyms] [k] radix_tree_tag_set
0.50% kworker/u8:5 [kernel.kallsyms] [k] xfs_do_writepage
0.50% xfs_io [kernel.kallsyms] [k] iov_iter_advance
0.47% xfs_io [kernel.kallsyms] [k] kmem_cache_alloc
0.46% xfs_io [kernel.kallsyms] [k] xfs_file_buffered_aio_write
0.46% xfs_io [kernel.kallsyms] [k] xfs_iunlock
0.45% kworker/u8:5 [kernel.kallsyms] [k] __wake_up_bit
0.45% xfs_io [kernel.kallsyms] [k] find_get_entry
0.45% xfs_io [kernel.kallsyms] [k] xfs_bmap_search_multi_extents
0.41% xfs_io [kernel.kallsyms] [k] xfs_iext_bno_to_ext
0.39% xfs_io [kernel.kallsyms] [k] iomap_apply
0.39% xfs_io [kernel.kallsyms] [k] xfs_file_aio_write_checks
0.38% xfs_io [kernel.kallsyms] [k] xfs_ilock
0.38% xfs_io [kernel.kallsyms] [k] xfs_inode_set_eofblocks_tag
0.37% xfs_io [kernel.kallsyms] [k] xfs_bmap_search_extents
0.30% xfs_io [kernel.kallsyms] [k] file_update_time
0.29% xfs_io [kernel.kallsyms] [k] __fget_light
0.27% xfs_io [kernel.kallsyms] [k] rw_verify_area
0.26% kworker/u8:5 [kernel.kallsyms] [k] unlock_page
0.26% xfs_io xfs_io [.] pwrite_f
0.25% xfs_io [kernel.kallsyms] [k] iomap_file_buffered_write
0.25% xfs_io [kernel.kallsyms] [k] node_dirty_ok
0.25% xfs_io [kernel.kallsyms] [k] xfs_bmbt_to_iomap
0.24% kworker/0:2 [kernel.kallsyms] [k] xfs_destroy_ioend
0.24% xfs_io [kernel.kallsyms] [k] __xfs_bmbt_get_all
0.24% xfs_io [kernel.kallsyms] [k] iov_iter_fault_in_readable
0.22% kworker/u8:5 [kernel.kallsyms] [k] xfs_start_buffer_writeback
0.22% xfs_io [kernel.kallsyms] [k] fsnotify
0.22% xfs_io [kernel.kallsyms] [k] sys_pwrite64
0.22% xfs_io [kernel.kallsyms] [k] xfs_file_iomap_begin
0.21% kworker/u8:5 [kernel.kallsyms] [k] pmem_do_bvec
0.21% kworker/u8:5 [kernel.kallsyms] [k] xfs_map_at_offset
0.18% kworker/u8:5 [kernel.kallsyms] [k] write_cache_pages
0.18% kworker/u8:5 [kernel.kallsyms] [k] xfs_map_buffer
0.17% kworker/u8:5 [kernel.kallsyms] [k] __test_set_page_writeback
0.17% xfs_io [kernel.kallsyms] [k] __alloc_pages_nodemask
0.17% xfs_io [kernel.kallsyms] [k] __fsnotify_parent
0.17% xfs_io [kernel.kallsyms] [k] block_write_end
0.17% xfs_io [kernel.kallsyms] [k] iomap_write_begin
0.17% xfs_io [kernel.kallsyms] [k] iov_iter_init
0.17% xfs_io [kernel.kallsyms] [k] percpu_up_read
0.17% xfs_io [kernel.kallsyms] [k] radix_tree_lookup_slot
0.16% xfs_io [kernel.kallsyms] [k] create_empty_buffers
0.16% xfs_io [kernel.kallsyms] [k] timespec_trunc
0.16% xfs_io [kernel.kallsyms] [k] wait_for_stable_page
0.16% xfs_io [kernel.kallsyms] [k] xfs_get_extsz_hint
0.14% kworker/0:2 [kernel.kallsyms] [k] test_clear_page_writeback
0.14% kworker/u8:5 [kernel.kallsyms] [k] release_pages
0.13% xfs_io [kernel.kallsyms] [k] iomap_write_end
0.13% xfs_io [kernel.kallsyms] [k] xfs_bmbt_get_startoff
0.12% kworker/u8:5 [kernel.kallsyms] [k] dec_zone_page_state
0.12% xfs_io [kernel.kallsyms] [k] alloc_page_buffers
0.12% xfs_io [kernel.kallsyms] [k] generic_write_checks
0.12% xfs_io [kernel.kallsyms] [k] percpu_down_read
0.12% xfs_io [kernel.kallsyms] [k] release_pages
0.12% xfs_io [kernel.kallsyms] [k] set_bh_page
0.12% xfs_io [kernel.kallsyms] [k] xfs_find_bdev_for_inode
0.12% xfs_io xfs_io [.] do_pwrite
0.10% kworker/u8:5 [kernel.kallsyms] [k] mark_buffer_async_write
0.10% kworker/u8:5 [kernel.kallsyms] [k] page_waitqueue
0.10% xfs_io [kernel.kallsyms] [k] PageHuge
0.10% xfs_io [kernel.kallsyms] [k] add_to_page_cache_lru
0.09% kworker/0:2 [kernel.kallsyms] [k] end_page_writeback
0.09% kworker/u8:5 [kernel.kallsyms] [k] find_get_pages_tag
0.09% kworker/u8:5 [kernel.kallsyms] [k] xfs_start_page_writeback
0.09% xfs_io [kernel.kallsyms] [k] create_page_buffers
0.09% xfs_io [kernel.kallsyms] [k] page_mapping
0.09% xfs_io [kernel.kallsyms] [k] xfs_bmbt_get_all
0.09% xfs_io [kernel.kallsyms] [k] xfs_file_iomap_end
0.08% kworker/u8:5 [kernel.kallsyms] [k] inc_node_page_state
0.08% kworker/u8:5 [kernel.kallsyms] [k] inc_zone_page_state
0.08% kworker/u8:5 [kernel.kallsyms] [k] page_mapping
0.08% kworker/u8:5 [kernel.kallsyms] [k] page_mkclean
0.08% xfs_io [kernel.kallsyms] [k] __sb_start_write
0.08% xfs_io [kernel.kallsyms] [k] current_kernel_time64
0.07% kworker/0:2 [kernel.kallsyms] [k] __wake_up_bit
0.07% kworker/u8:5 [kernel.kallsyms] [k] page_mapped
0.07% xfs_io [kernel.kallsyms] [k] __lru_cache_add
0.07% xfs_io [kernel.kallsyms] [k] current_fs_time
0.07% xfs_io [kernel.kallsyms] [k] grab_cache_page_write_begin
0.07% xfs_io [kernel.kallsyms] [k] xfs_iext_get_ext
0.05% kworker/u8:5 [kernel.kallsyms] [k] pmem_make_request
0.05% kworker/u8:5 [kernel.kallsyms] [k] xfs_add_to_ioend
0.05% xfs_io [kernel.kallsyms] [k] __fdget
0.05% xfs_io [kernel.kallsyms] [k] __find_get_block_slow
0.05% xfs_io [kernel.kallsyms] [k] __set_page_dirty
0.05% xfs_io [kernel.kallsyms] [k] alloc_buffer_head
0.05% xfs_io [kernel.kallsyms] [k] radix_tree_lookup
0.05% xfs_io [kernel.kallsyms] [k] radix_tree_tagged
0.05% xfs_io [kernel.kallsyms] [k] xfs_bmbt_get_blockcount
0.05% xfs_io [kernel.kallsyms] [k] xfs_fsb_to_db
0.04% kworker/0:2 [kernel.kallsyms] [k] dec_zone_page_state
0.04% kworker/u8:5 [kernel.kallsyms] [k] dec_node_page_state
0.04% xfs_io [kernel.kallsyms] [k] __radix_tree_preload
0.04% xfs_io [kernel.kallsyms] [k] __sb_end_write
0.03% kworker/0:2 [kernel.kallsyms] [k] dec_node_page_state
0.03% kworker/0:2 [kernel.kallsyms] [k] inc_node_page_state
0.03% kworker/0:2 [kernel.kallsyms] [k] page_mapping
0.03% kworker/u8:5 [kernel.kallsyms] [k] radix_tree_next_chunk
0.03% kworker/u8:5 [kernel.kallsyms] [k] xfs_fsb_to_db
0.03% xfs_io [kernel.kallsyms] [k] _raw_spin_lock_irqsave
0.03% xfs_io [kernel.kallsyms] [k] cache_alloc_refill
0.03% xfs_io [kernel.kallsyms] [k] lru_cache_add
0.01% kworker/0:2 [kernel.kallsyms] [k] cache_reap
0.01% kworker/0:2 [kernel.kallsyms] [k] mempool_free
0.01% kworker/0:2 [kernel.kallsyms] [k] page_waitqueue
0.01% kworker/u8:5 [kernel.kallsyms] [k] bio_add_page
0.01% kworker/u8:5 [kernel.kallsyms] [k] kmem_cache_alloc
0.01% kworker/u8:5 [kernel.kallsyms] [k] lru_add_drain_cpu
0.01% kworker/u8:5 [kernel.kallsyms] [k] mempool_alloc
0.01% kworker/u8:5 [kernel.kallsyms] [k] pagevec_lookup_tag
0.01% kworker/u8:5 [kernel.kallsyms] [k] queue_delayed_work_on
0.01% kworker/u8:5 [kernel.kallsyms] [k] queue_work_on
0.01% kworker/u8:5 [kernel.kallsyms] [k] run_timer_softirq
0.01% kworker/u8:5 [kernel.kallsyms] [k] update_group_capacity
0.01% kworker/u8:5 [kernel.kallsyms] [k] xfs_trans_reserve
0.01% swapper [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
0.01% xfs_io [kernel.kallsyms] [k] _cond_resched
0.01% xfs_io [kernel.kallsyms] [k] mod_zone_page_state
0.01% xfs_io [kernel.kallsyms] [k] pagevec_lru_move_fn
0.01% xfs_io [kernel.kallsyms] [k] radix_tree_maybe_preload
0.01% xfs_io [kernel.kallsyms] [k] unmap_underlying_metadata
0.01% xfs_io [kernel.kallsyms] [k] xfs_bmap_worst_indlen
0.01% xfs_io ld-2.19.so [.] 0x000000000000d866
0.01% xfs_io libc-2.19.so [.] 0x000000000008a8da
0.01% xfs_io xfs_io [.] pwrite64@plt