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 primary test workload was dd to a tmpfs file that was 1/10th the size
of memory so that dirty balancing and reclaim should not be factors.
loopdd Throughput
3.15.0-rc1 3.15.0-rc1
vanilla microopt-v1r11
Min 3993.6000 ( 0.00%) 4096.0000 ( 2.56%)
Mean 4766.7200 ( 0.00%) 4896.4267 ( 2.72%)
Stddev 164.5053 ( 0.00%) 167.7316 ( 1.96%)
Max 4812.8000 ( 0.00%) 5120.0000 ( 6.38%)
Respectable increase in throughput. The figures are misleading though because
dd reports in GB/sec so there is a lot of noise. The actual time to completiono
is easier to see
loopdd Time
3.15.0-rc1 3.15.0-rc1
vanilla microopt-v1r11
Min time0.3521 ( 0.00%)0.3317 ( 5.80%)
Mean time0.3570 ( 0.00%)0.3458 ( 3.14%)
Stddev time0.0140 ( 0.00%)0.0112 ( 20.59%)
Max time0.4230 ( 0.00%)0.4083 ( 3.49%)
The time to dd the data is noticably reduced
3.15.0-rc1 3.15.0-rc1
vanillamicroopt-v1r11
User 10.86 10.78
System 70.21 67.12
Elapsed 92.43 89.42
And the system CPU overhead is lower.
A series of tests against various filesystems as well as a general
benchmark are still running but I thought I would send the series out
as-is for comment.
Documentation/sysctl/vm.txt | 17 ++--
arch/ia64/include/asm/topology.h | 3 +-
arch/powerpc/include/asm/topology.h | 8 +-
include/linux/cpuset.h | 29 +++++++
include/linux/mmzone.h | 14 ++-
include/linux/page-flags.h | 2 +
include/linux/pageblock-flags.h | 18 +++-
include/linux/swap.h | 7 +-
include/linux/topology.h | 3 +-
kernel/cpuset.c | 8 +-
mm/filemap.c | 58 ++++++++-----
mm/page_alloc.c | 164 ++++++++++++++++++++----------------
mm/shmem.c | 8 +-
mm/swap.c | 13 ++-
14 files changed, 226 insertions(+), 126 deletions(-)
--
1.8.4.5
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