don't check current key in DBIter::Next() #679
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When iter_ is pointing to current key, we can safely move to the next key to avoid checking current key, which is of course not necessary. Benchmark shows that 'readseq' has about 8% performance improvement. Without patch: >./db_bench --benchmarks=readseq --num=$((4<<20)) --db=/tmp/db --use_existing_db=1 LevelDB: version 1.21 Date: Thu Apr 25 09:37:21 2019 CPU: 32 * Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz CPUCache: 20480 KB Keys: 16 bytes each Values: 100 bytes each (50 bytes after compression) Entries: 4194304 RawSize: 464.0 MB (estimated) FileSize: 264.0 MB (estimated) ------------------------------------------------ readseq : 0.196 micros/op; 565.7 MB/s With patch: >./db_bench --benchmarks=readseq --num=$((4<<20)) --db=/tmp/db --use_existing_db=1 LevelDB: version 1.21 Date: Thu Apr 25 09:38:20 2019 CPU: 32 * Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz CPUCache: 20480 KB Keys: 16 bytes each Values: 100 bytes each (50 bytes after compression) Entries: 4194304 RawSize: 464.0 MB (estimated) FileSize: 264.0 MB (estimated) ------------------------------------------------ readseq : 0.181 micros/op; 612.3 MB/s Signed-off-by: Kyle Zhang <kyle@smartx.com>
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Thanks. I looked carefully and this looks correct to me. |
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@cmumford Could you take some time to look at this patch? |
maochongxin
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Jul 21, 2022
The windows SDK headers don't have self-consistent casing anyway, and many projects consistently use lowercase for them, in order to fix crosscompilation with mingw headers.
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When iter_ is pointing to current key, we can safely move to the next
key to avoid checking current key, which is of course not necessary.
Benchmark shows that 'readseq' has about 8% performance improvement.
Without patch:
readseq : 0.196 micros/op; 565.7 MB/s
With patch:
readseq : 0.181 micros/op; 612.3 MB/s
Signed-off-by: Kyle Zhang kyle@smartx.com