Changelog since V2
o Fewer atomic operations in buffer discards (mgorman)
o Remove number_of_cpusets and use ref count in jump labels (peterz)
o Optimise set loop for pageblock flags further (peterz)
o Remove unnecessary parameters when setting pageblock flags (vbabka)
o Rework how PG_waiters are set/cleared to avoid changing wait.c (mgorman)
I was investigating a performance bug that looked like dd to tmpfs
had regressed. The bulk of the problem turned out to be a difference
in Kconfig but it got me looking at the unnecessary overhead in tmpfs,
mark_page_accessed and parts of the allocator. This series is the result.
The patches themselves have details of the performance results but here
are a few showing the impact of the whole series. This is the result of
dd'ing to a file multiple times on tmpfs
sync DD to tmpfs
Throughput 3.15.0-rc4 3.15.0-rc4
vanilla fullseries-v3
Min 4096.0000 ( 0.00%) 4300.8000 ( 5.00%)
Mean 4785.4933 ( 0.00%) 5003.9467 ( 4.56%)
TrimMean 4812.8000 ( 0.00%) 5028.5714 ( 4.48%)
Stddev 147.0509 ( 0.00%) 191.9981 ( 30.57%)
Max 5017.6000 ( 0.00%) 5324.8000 ( 6.12%)
sync DD to tmpfs
Elapsed Time 3.15.0-rc4 3.15.0-rc4
vanilla fullseries-v3
Min elapsed 0.4200 ( 0.00%) 0.3900 ( 7.14%)
Mean elapsed 0.4947 ( 0.00%) 0.4527 ( 8.49%)
TrimMean elapsed 0.4968 ( 0.00%) 0.4539 ( 8.63%)
Stddev elapsed 0.0255 ( 0.00%) 0.0340 (-33.02%)
Max elapsed 0.5200 ( 0.00%) 0.4800 ( 7.69%)
TrimMean elapsed 0.4796 ( 0.00%) 0.4179 ( 12.88%)
Stddev elapsed 0.0353 ( 0.00%) 0.0379 ( -7.23%)
Max elapsed 0.5100 ( 0.00%) 0.4800 ( 5.88%)
sync DD to ext4
Throughput 3.15.0-rc4 3.15.0-rc4
vanilla fullseries-v3
Min 113.0000 ( 0.00%) 117.0000 ( 3.54%)
Mean 116.3000 ( 0.00%) 119.6667 ( 2.89%)
TrimMean 116.2857 ( 0.00%) 119.5714 ( 2.83%)
Stddev 1.6961 ( 0.00%) 1.1643 (-31.35%)
Max 120.0000 ( 0.00%) 122.0000 ( 1.67%)
sync DD to ext4
Elapsed time 3.15.0-rc4 3.15.0-rc4
vanilla fullseries-v3
Min elapsed 13.9500 ( 0.00%) 13.6900 ( 1.86%)
Mean elapsed 14.4253 ( 0.00%) 14.0010 ( 2.94%)
TrimMean elapsed 14.4321 ( 0.00%) 14.0161 ( 2.88%)
Stddev elapsed 0.2047 ( 0.00%) 0.1423 ( 30.46%)
Max elapsed 14.8300 ( 0.00%) 14.3100 ( 3.51%)
async DD to ext4
Elapsed time 3.15.0-rc4 3.15.0-rc4
vanilla fullseries-v3
Min elapsed 0.7900 ( 0.00%) 0.7800 ( 1.27%)
Mean elapsed 12.4023 ( 0.00%) 12.2957 ( 0.86%)
TrimMean elapsed 13.2036 ( 0.00%) 13.0918 ( 0.85%)
Stddev elapsed 3.3286 ( 0.00%) 2.9842 ( 10.35%)
Max elapsed 18.6000 ( 0.00%) 13.4300 ( 27.80%)
This table shows the latency in usecs of accessing ext4-backed
mappings of various sizes
lat_mmap
3.15.0-rc4 3.15.0-rc4
vanilla fullseries-v3
Procs 107M 564.0000 ( 0.00%) 546.0000 ( 3.19%)
Procs 214M 1123.0000 ( 0.00%) 1090.0000 ( 2.94%)
Procs 322M 1636.0000 ( 0.00%) 1395.0000 ( 14.73%)
Procs 429M 2076.0000 ( 0.00%) 2051.0000 ( 1.20%)
Procs 536M 2518.0000 ( 0.00%) 2482.0000 ( 1.43%)
Procs 644M 3008.0000 ( 0.00%) 2978.0000 ( 1.00%)
Procs 751M 3506.0000 ( 0.00%) 3450.0000 ( 1.60%)
Procs 859M 3988.0000 ( 0.00%) 3756.0000 ( 5.82%)
Procs 966M 4544.0000 ( 0.00%) 4310.0000 ( 5.15%)
Procs 1073M 4960.0000 ( 0.00%) 4928.0000 ( 0.65%)
Procs 1181M 5342.0000 ( 0.00%) 5144.0000 ( 3.71%)
Procs 1288M 5573.0000 ( 0.00%) 5427.0000 ( 2.62%)
Procs 1395M 5777.0000 ( 0.00%) 6056.0000 ( -4.83%)
Procs 1503M 6141.0000 ( 0.00%) 5963.0000 ( 2.90%)
Procs 1610M 6689.0000 ( 0.00%) 6331.0000 ( 5.35%)
Procs 1717M 8839.0000 ( 0.00%) 6807.0000 ( 22.99%)
Procs 1825M 8399.0000 ( 0.00%) 9062.0000 ( -7.89%)
Procs 1932M 7871.0000 ( 0.00%) 8778.0000 (-11.52%)
Procs 2040M 8235.0000 ( 0.00%) 8081.0000 ( 1.87%)
Procs 2147M 8861.0000 ( 0.00%) 8337.0000 ( 5.91%)
In general the system CPU overhead is lower.
arch/tile/mm/homecache.c | 2 +-
fs/btrfs/extent_io.c | 11 +-
fs/btrfs/file.c | 5 +-
fs/buffer.c | 21 ++-
fs/ext4/mballoc.c | 14 +-
fs/f2fs/checkpoint.c | 3 -
fs/f2fs/node.c | 2 -
fs/fuse/dev.c | 2 +-
fs/fuse/file.c | 2 -
fs/gfs2/aops.c | 1 -
fs/gfs2/meta_io.c | 4 +-
fs/ntfs/attrib.c | 1 -
fs/ntfs/file.c | 1 -
include/linux/buffer_head.h | 5 +
include/linux/cpuset.h | 46 +++++
include/linux/gfp.h | 4 +-
include/linux/jump_label.h | 20 ++-
include/linux/mmzone.h | 21 ++-
include/linux/page-flags.h | 20 +++
include/linux/pageblock-flags.h | 30 +++-
include/linux/pagemap.h | 115 +++++++++++-
include/linux/swap.h | 9 +-
kernel/cpuset.c | 10 +-
mm/filemap.c | 380 +++++++++++++++++++++++++---------------
mm/page_alloc.c | 229 ++++++++++++++----------
mm/shmem.c | 8 +-
mm/swap.c | 27 ++-
mm/swap_state.c | 2 +-
mm/vmscan.c | 9 +-
29 files changed, 686 insertions(+), 318 deletions(-)
--
1.8.4.5
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