On Fri, Jul 27, 2012 at 07:08:35AM -0400, Chris Mason wrote: > On Mon, Jul 23, 2012 at 12:42:03AM -0600, Marc MERLIN wrote: > > > > 22 seconds for 15K files on an SSD is super slow and being 5 times > > slower than a spinning disk with the same data. > > What's going on? > > Hi Marc, > > The easiest way to figure out is with latencytop. I'd either run the > latencytop gui or use the latencytop -c patch which sends a text dump to > the console. > > This is assuming that you're not pegged at 100% CPU... > > https://oss.oracle.com/~mason/latencytop.patch Thanks for the patch, and yes I can confirm I'm definitely not pegged on CPU (not even close and I get the same problem with unencrypted filesystem, actually du -sh is exactly the same speed on encrypted and unecrypted). Here's the result I think you were looking for. I'm not good at reading this, but hopefully it tells you something useful :) The full run is here if that helps: http://marc.merlins.org/tmp/latencytop.txt Process du (6748) Total: 4280.5 msec Reading directory content 15.2 msec 11.0 % sleep_on_page wait_on_page_bit read_extent_buffer_pages btree_read_extent_buffer_pages.constprop.110 read_tree_block read_block_for_search.isra.32 btrfs_next_leaf btrfs_real_readdir vfs_readdir sys_getdents system_call_fastpath [sleep_on_page] 13.5 msec 88.2 % sleep_on_page wait_on_page_bit read_extent_buffer_pages btree_read_extent_buffer_pages.constprop.110 read_tree_block read_block_for_search.isra.32 btrfs_search_slot btrfs_lookup_csum __btrfs_lookup_bio_sums btrfs_lookup_bio_sums btrfs_submit_compressed_read btrfs_submit_bio_hook Page fault 12.9 msec 0.6 % sleep_on_page_killable wait_on_page_bit_killable __lock_page_or_retry filemap_fault __do_fault handle_pte_fault handle_mm_fault do_page_fault page_fault Executing a program 7.1 msec 0.2 % sleep_on_page_killable __lock_page_killable generic_file_aio_read do_sync_read vfs_read kernel_read prepare_binprm do_execve_common.isra.27 do_execve sys_execve stub_execve Process du (6748) Total: 9517.4 msec [sleep_on_page] 23.0 msec 82.8 % sleep_on_page wait_on_page_bit read_extent_buffer_pages btree_read_extent_buffer_pages.constprop.110 read_tree_block read_block_for_search.isra.32 btrfs_search_slot btrfs_lookup_inode btrfs_iget btrfs_lookup_dentry btrfs_lookup __lookup_hash Reading directory content 13.2 msec 17.2 % sleep_on_page wait_on_page_bit read_extent_buffer_pages btree_read_extent_buffer_pages.constprop.110 read_tree_block read_block_for_search.isra.32 btrfs_search_slot btrfs_real_readdir vfs_readdir sys_getdents system_call_fastpath Process du (6748) Total: 9524.0 msec [sleep_on_page] 17.1 msec 88.5 % sleep_on_page wait_on_page_bit read_extent_buffer_pages btree_read_extent_buffer_pages.constprop.110 read_tree_block read_block_for_search.isra.32 btrfs_search_slot btrfs_lookup_inode btrfs_iget btrfs_lookup_dentry btrfs_lookup __lookup_hash Reading directory content 16.0 msec 11.5 % sleep_on_page wait_on_page_bit read_extent_buffer_pages btree_read_extent_buffer_pages.constprop.110 read_tree_block read_block_for_search.isra.32 btrfs_search_slot btrfs_real_readdir vfs_readdir sys_getdents system_call_fastpath -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
