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Message-ID: <20140109025715.GA11984@localhost>
Date: Thu, 9 Jan 2014 10:57:15 +0800
From: Fengguang Wu <fengguang.wu@...el.com>
To: Dave Chinner <david@...morbit.com>
Cc: Glauber Costa <glommer@...allels.com>,
Linux Memory Management List <linux-mm@...ck.org>,
linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
lkp@...ux.intel.com
Subject: Re: [numa shrinker] 9b17c62382: -36.6% regression on sparse file copy
Hi Dave,
As you suggested, I added tests for ext4 and btrfs, the results are
the same.
Then I tried running perf record for 10 seconds starting from 200s.
(The test runs for 410s). I see several warning messages and hope
they do not impact the accuracy too much:
[ 252.608069] perf samples too long (2532 > 2500), lowering kernel.perf_event_max_sample_rate to 50000
[ 252.608863] perf samples too long (2507 > 2500), lowering kernel.perf_event_max_sample_rate to 25000
[ 252.609422] INFO: NMI handler (perf_event_nmi_handler) took too long to run: 1.389 msecs
Anyway the noticeable perf change are:
1d3d4437eae1bb2 9b17c62382dd2e7507984b989
--------------- -------------------------
12.15 ~10% +209.8% 37.63 ~ 2% brickland2/debug2/vm-scalability/300s-btrfs-lru-file-readtwice
12.88 ~16% +189.4% 37.27 ~ 0% brickland2/debug2/vm-scalability/300s-ext4-lru-file-readtwice
15.24 ~ 9% +146.0% 37.50 ~ 1% brickland2/debug2/vm-scalability/300s-xfs-lru-file-readtwice
40.27 +179.1% 112.40 TOTAL perf-profile.cpu-cycles._raw_spin_lock.grab_super_passive.super_cache_count.shrink_slab.do_try_to_free_pages
1d3d4437eae1bb2 9b17c62382dd2e7507984b989
--------------- -------------------------
11.91 ~12% +218.2% 37.89 ~ 2% brickland2/debug2/vm-scalability/300s-btrfs-lru-file-readtwice
12.47 ~16% +200.3% 37.44 ~ 0% brickland2/debug2/vm-scalability/300s-ext4-lru-file-readtwice
15.36 ~11% +145.4% 37.68 ~ 1% brickland2/debug2/vm-scalability/300s-xfs-lru-file-readtwice
39.73 +184.5% 113.01 TOTAL perf-profile.cpu-cycles._raw_spin_lock.put_super.drop_super.super_cache_count.shrink_slab
perf report for 9b17c62382dd2e7507984b989:
# Overhead Command Shared Object Symbol
# ........ ............... .................. ..............................................
#
77.74% dd [kernel.kallsyms] [k] _raw_spin_lock
|
--- _raw_spin_lock
|
|--47.65%-- grab_super_passive
| super_cache_count
| shrink_slab
| do_try_to_free_pages
| try_to_free_pages
| __alloc_pages_nodemask
| alloc_pages_current
| __page_cache_alloc
| __do_page_cache_readahead
| ra_submit
| ondemand_readahead
| |
| |--92.13%-- page_cache_async_readahead
| | generic_file_aio_read
| | xfs_file_aio_read
| | do_sync_read
| | vfs_read
| | SyS_read
| | system_call_fastpath
| | read
| |
| --7.87%-- page_cache_sync_readahead
| generic_file_aio_read
| xfs_file_aio_read
| do_sync_read
| vfs_read
| SyS_read
| system_call_fastpath
| read
|--47.48%-- put_super
| drop_super
| super_cache_count
| shrink_slab
| do_try_to_free_pages
| try_to_free_pages
| __alloc_pages_nodemask
| alloc_pages_current
| __page_cache_alloc
| __do_page_cache_readahead
| ra_submit
| ondemand_readahead
| |
| |--92.04%-- page_cache_async_readahead
| | generic_file_aio_read
| | xfs_file_aio_read
| | do_sync_read
| | vfs_read
| | SyS_read
| | system_call_fastpath
| | read
| |
| --7.96%-- page_cache_sync_readahead
| generic_file_aio_read
| xfs_file_aio_read
| do_sync_read
| vfs_read
| SyS_read
| system_call_fastpath
| read
--4.87%-- [...]
The full changeset is attached.
Thanks,
Fengguang
View attachment "9b17c62382dd2e7507984b9890bf44e070cdd8bb" of type "text/plain" (86538 bytes)
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