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https://issues.apache.org/jira/browse/CASSANDRA-3623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13175595#comment-13175595
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Vijay commented on CASSANDRA-3623:
----------------------------------
Hot Methods before the patch (trunk):
Excl. User CPU Name
sec. %
1480.474 100.00 <Total>
756.717 51.11 crc32
387.767 26.19 <static>@0x54999 (<snappy-1.0.4.1-libsnappyjava.so>)
54.814 3.70
org.apache.cassandra.io.compress.CompressedRandomAccessReader.<init>(java.lang.String,
org.apache.cassandra.io.compress.CompressionMetadata, boolean)
46.676 3.15
org.apache.cassandra.io.util.RandomAccessReader.<init>(java.io.File, int,
boolean)
45.697 3.09 Copy::pd_disjoint_words(HeapWord*, HeapWord*, unsigned long)
39.417 2.66 memcpy
36.931 2.49 <static>@0xd8e9 (<libpthread-2.5.so>)
23.272 1.57 CompactibleFreeListSpace::block_size(const HeapWord*) const
22.766 1.54 SpinPause
12.593 0.85 BlockOffsetArrayNonContigSpace::block_start_unsafe(const
void*) const
9.304 0.63 CardTableModRefBSForCTRS::card_will_be_scanned(signed char)
8.468 0.57 CardTableModRefBS::non_clean_card_iterate_work(MemRegion,
MemRegionClosure*, bool)
8.051 0.54
ParallelTaskTerminator::offer_termination(TerminatorTerminator*)
5.400 0.36 madvise
4.619 0.31 CardTableModRefBS::process_chunk_boundaries(Space*,
DirtyCardToOopClosure*, MemRegion, MemRegion, signed char**, unsigned long,
unsigned long)
1.584 0.11 CardTableModRefBS::dirty_card_range_after_reset(MemRegion,
bool, int)
1.551 0.10 SweepClosure::do_blk_careful(HeapWord*)
Hot Methods After the patch:
sec. %
537.681 100.00 <Total>
529.719 98.52 <static>@0x54999 (<snappy-1.0.4.1-libsnappyjava.so>)
4.168 0.78 memcpy
0.143 0.03 <Unknown>
0.121 0.02 send
0.121 0.02 sun.misc.Unsafe.park(boolean, long)
0.110 0.02 sun.misc.Unsafe.unpark(java.lang.Object)
0.088 0.02 Interpreter
0.077 0.01 org.apache.cassandra.utils.EstimatedHistogram.max()
0.077 0.01 recv
0.066 0.01 SpinPause
0.055 0.01 org.apache.cassandra.utils.EstimatedHistogram.mean()
0.044 0.01 java.lang.Object.wait(long)
0.044 0.01 org.apache.cassandra.utils.EstimatedHistogram.min()
0.044 0.01 __pthread_cond_signal
0.044 0.01 vtable stub
0.033 0.01 java.lang.Object.notify()
0.033 0.01
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(java.lang.Runnable)
0.033 0.01
org.apache.cassandra.io.compress.CompressedMappedFileDataInput.read()
0.033 0.01 PhaseLive::compute(unsigned)
0.033 0.01 poll
0.022 0.00 Arena::contains(const void*) const
0.022 0.00 CompactibleFreeListSpace::free() const
0.022 0.00 I2C/C2I adapters
0.022 0.00 IndexSetIterator::advance_and_next()
0.022 0.00 java.lang.Class.forName0(java.lang.String, boolean,
java.lang.ClassLoader)
0.022 0.00 java.lang.Long.getChars(long, int, char[])
0.022 0.00 java.nio.Bits.swap(int)
Before this patch response times:
Epoch Rds/s RdLat Wrts/s WrtLat %user %sys %idle
%iowait %steal md0r/s w/s rMB/s wMB/s NetRxKb NetTxKb Percentiles
Read Write Compacts
1324587443 15 186.305 0 0.000 27.85 0.02 71.83
0.24 0.05 3.89 0.00 0.12 0.00 41 45 99th
545.791 ms 95th 454.826 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587455 15 1142.712 0 0.000 39.55 0.13 57.61
2.50 0.21 118.30 0.30 2.20 0.00 34 36 99th
8409.007 ms 95th 8409.007 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587467 10 171.808 0 0.000 23.83 0.04 76.05
0.04 0.05 4.80 0.00 0.14 0.00 127 33 99th
454.826 ms 95th 315.852 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587478 10 182.775 0 0.000 20.43 0.04 79.47
0.01 0.05 1.60 0.40 0.04 0.00 30 37 99th
379.022 ms 95th 379.022 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587490 13 190.893 0 0.000 27.58 0.03 72.20
0.14 0.06 3.20 0.50 0.09 0.00 39 42 99th
545.791 ms 95th 379.022 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587503 28 358.719 0 0.000 52.24 0.08 46.20
1.40 0.09 159.40 0.00 3.16 0.00 196 71 99th
3379.391 ms 95th 943.127 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587517 13 194.281 0 0.000 16.68 0.02 83.23
0.04 0.02 2.40 0.30 0.07 0.00 38 41 99th
785.939 ms 95th 545.791 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587535 36 662.410 0 0.000 58.34 0.08 41.42
0.06 0.10 3.60 0.20 0.11 0.00 173 81 99th
3379.391 ms 95th 2816.159 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324587547 22 189.838 0 0.000 37.68 0.05 62.03
0.16 0.09 5.32 0.49 0.16 0.00 56 63 99th
454.826 ms 95th 379.022 ms 99th 0.00 ms 95th 0.00 ms Pen/0
After this patch response times:
Epoch Rds/s RdLat Wrts/s WrtLat %user %sys
%idle %iowait %steal md0r/s w/s rMB/s wMB/s NetRxKb NetTxKb
Percentiles Read Write Compacts
1324665227 18 97.724 0 0.000
21.49 0.02 78.40 0.05 0.04 4.00 0.40 0.12 0.00 167
45 99th 152.321 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665239 26 107.279 0 0.000 29.57
0.04 70.18 0.16 0.05 8.70 0.00 0.22 0.00 56 60
99th 219.342 ms 95th 152.321 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665251 27 105.965 0 0.000 28.37
0.05 70.97 0.54 0.08 6.49 0.60 0.11 0.00 70 73
99th 182.785 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665262 21 103.396 0 0.000 22.84
0.03 77.08 0.01 0.04 0.80 0.10 0.03 0.00 43 46
99th 126.934 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665274 27 104.916 0 0.000 32.78
0.04 67.06 0.06 0.06 7.70 0.10 0.14 0.00 161 64
99th 182.785 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665286 21 105.094 0 0.000 21.33
0.01 78.53 0.09 0.04 3.49 0.30 0.10 0.00 47 51
99th 182.785 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665297 21 104.898 0 0.000 22.95
0.01 76.91 0.10 0.03 4.40 0.00 0.12 0.00 46 48
99th 182.785 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665309 25 104.844 0 0.000 27.31
0.03 72.53 0.09 0.05 4.00 0.60 0.12 0.00 199 71
99th 152.321 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665321 26 106.604 0 0.000 32.63
0.05 66.99 0.27 0.06 5.40 0.10 0.11 0.00 54 57
99th 219.342 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665332 21 104.086 0 0.000 24.66
0.01 75.19 0.10 0.04 3.30 0.00 0.10 0.00 146 51
99th 152.321 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665344 24 108.079 0 0.000 29.26
0.04 70.50 0.15 0.06 3.10 0.40 0.09 0.00 56 59
99th 219.342 ms 95th 152.321 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665356 32 105.465 0 0.000 32.67
0.04 66.97 0.25 0.08 8.80 0.00 0.11 0.00 60 63
99th 182.785 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665368 15 103.112 0 0.000 16.61
0.03 83.33 0.01 0.03 0.80 0.40 0.02 0.00 48 53
99th 126.934 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
1324665379 24 104.599 0 0.000 25.87
0.03 74.05 0.01 0.05 2.59 0.10 0.08 0.00 51 54
99th 182.785 ms 95th 126.934 ms 99th 0.00 ms 95th 0.00 ms Pen/0
Looks like we have 50% better performance with this.
Pavel, you are right the biggest gain was because we reduced the memcpy.
> use MMapedBuffer in CompressedSegmentedFile.getSegment
> ------------------------------------------------------
>
> Key: CASSANDRA-3623
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3623
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 1.1
> Reporter: Vijay
> Assignee: Vijay
> Labels: compression
> Fix For: 1.1
>
> Attachments: 0001-MMaped-Compression-segmented-file-v2.patch,
> 0001-MMaped-Compression-segmented-file.patch,
> 0002-tests-for-MMaped-Compression-segmented-file-v2.patch
>
>
> CompressedSegmentedFile.getSegment seem to open a new file and doesnt seem to
> use the MMap and hence a higher CPU on the nodes and higher latencies on
> reads.
> This ticket is to implement the TODO mentioned in CompressedRandomAccessReader
> // TODO refactor this to separate concept of "buffer to avoid lots of read()
> syscalls" and "compression buffer"
> but i think a separate class for the Buffer will be better.
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