Linus Torvalds <torva...@linux-foundation.org> writes: > On Wed, Aug 10, 2016 at 5:11 PM, Huang, Ying <ying.hu...@intel.com> wrote: >> >> Here is the comparison result with perf-profile data. > > Heh. The diff is actually harder to read than just showing A/B > state.The fact that the call chain shows up as part of the symbol > makes it even more so. > > For example: > >> 0.00 ± -1% +Inf% 1.68 ± 1% >> perf-profile.cycles-pp.__add_to_page_cache_locked.add_to_page_cache_lru.pagecache_get_page.grab_cache_page_write_begin.iomap_write_begin >> 1.80 ± 1% -100.0% 0.00 ± -1% >> perf-profile.cycles-pp.__add_to_page_cache_locked.add_to_page_cache_lru.pagecache_get_page.grab_cache_page_write_begin.xfs_vm_write_begin > > Ok, so it went from 1.8% to 1.68%, and isn't actually that big of a > change, but it shows up as a big change because the caller changed > from xfs_vm_write_begin to iomap_write_begin. > > There's a few other cases of that too. > > So I think it would actually be easier to just see "what 20 functions > were the hottest" (or maybe 50) before and after separately (just > sorted by cycles), without the diff part. Because the diff is really > hard to read.
Here it is, Before: "perf-profile.func.cycles-pp.intel_idle": 16.88, "perf-profile.func.cycles-pp.copy_user_enhanced_fast_string": 3.94, "perf-profile.func.cycles-pp.memset_erms": 3.26, "perf-profile.func.cycles-pp.__block_commit_write.isra.24": 2.47, "perf-profile.func.cycles-pp.___might_sleep": 2.33, "perf-profile.func.cycles-pp.__mark_inode_dirty": 1.88, "perf-profile.func.cycles-pp.unlock_page": 1.69, "perf-profile.func.cycles-pp.up_write": 1.61, "perf-profile.func.cycles-pp.__block_write_begin_int": 1.56, "perf-profile.func.cycles-pp.down_write": 1.55, "perf-profile.func.cycles-pp.mark_buffer_dirty": 1.53, "perf-profile.func.cycles-pp.entry_SYSCALL_64_fastpath": 1.47, "perf-profile.func.cycles-pp.generic_write_end": 1.36, "perf-profile.func.cycles-pp.generic_perform_write": 1.33, "perf-profile.func.cycles-pp.__radix_tree_lookup": 1.32, "perf-profile.func.cycles-pp.__might_sleep": 1.26, "perf-profile.func.cycles-pp._raw_spin_lock": 1.17, "perf-profile.func.cycles-pp.vfs_write": 1.14, "perf-profile.func.cycles-pp.__xfs_get_blocks": 1.07, "perf-profile.func.cycles-pp.xfs_file_write_iter": 1.03, "perf-profile.func.cycles-pp.pagecache_get_page": 1.03, "perf-profile.func.cycles-pp.native_queued_spin_lock_slowpath": 0.98, "perf-profile.func.cycles-pp.get_page_from_freelist": 0.94, "perf-profile.func.cycles-pp.rwsem_spin_on_owner": 0.94, "perf-profile.func.cycles-pp.__vfs_write": 0.87, "perf-profile.func.cycles-pp.iov_iter_copy_from_user_atomic": 0.87, "perf-profile.func.cycles-pp.xfs_file_buffered_aio_write": 0.84, "perf-profile.func.cycles-pp.find_get_entry": 0.79, "perf-profile.func.cycles-pp._raw_spin_lock_irqsave": 0.78, After: "perf-profile.func.cycles-pp.intel_idle": 16.82, "perf-profile.func.cycles-pp.copy_user_enhanced_fast_string": 3.27, "perf-profile.func.cycles-pp.memset_erms": 2.6, "perf-profile.func.cycles-pp.xfs_bmapi_read": 2.24, "perf-profile.func.cycles-pp.___might_sleep": 2.04, "perf-profile.func.cycles-pp.mark_page_accessed": 1.93, "perf-profile.func.cycles-pp.__block_write_begin_int": 1.78, "perf-profile.func.cycles-pp.up_write": 1.72, "perf-profile.func.cycles-pp.xfs_iext_bno_to_ext": 1.7, "perf-profile.func.cycles-pp.__block_commit_write.isra.24": 1.65, "perf-profile.func.cycles-pp.down_write": 1.51, "perf-profile.func.cycles-pp.__mark_inode_dirty": 1.51, "perf-profile.func.cycles-pp.unlock_page": 1.43, "perf-profile.func.cycles-pp.xfs_bmap_search_multi_extents": 1.25, "perf-profile.func.cycles-pp.xfs_bmap_search_extents": 1.23, "perf-profile.func.cycles-pp.mark_buffer_dirty": 1.21, "perf-profile.func.cycles-pp.xfs_iomap_write_delay": 1.19, "perf-profile.func.cycles-pp.xfs_iomap_eof_want_preallocate.constprop.8": 1.15, "perf-profile.func.cycles-pp.iomap_write_actor": 1.14, "perf-profile.func.cycles-pp.__might_sleep": 1.12, "perf-profile.func.cycles-pp.__radix_tree_lookup": 1.08, "perf-profile.func.cycles-pp.entry_SYSCALL_64_fastpath": 1.07, "perf-profile.func.cycles-pp.pagecache_get_page": 0.95, "perf-profile.func.cycles-pp._raw_spin_lock": 0.95, "perf-profile.func.cycles-pp.xfs_bmapi_delay": 0.93, "perf-profile.func.cycles-pp.vfs_write": 0.92, "perf-profile.func.cycles-pp.xfs_file_write_iter": 0.86, Best Regards, Huang, Ying
