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Bug
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Resolution: Fixed
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Minor
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None
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None
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master
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3
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9223372036854775807
parallel readahead is enabled by default in master, it contributes to sequential read performance a lot.
However, if the number of IO thread is increased (e.g. NP=NCPU), read performance drops and it's lower than without readahead. it needs to be tunning and optimization.
Here is test configuration and resutls.
Client 2 x Platinum 8160 CPU @ 2.10GHz, 192GB memory, 2 x IB-EDR(multi-rail) CentOS7.6(3.10.0-957.27.2.el7.x86_64) OFED-4.5
for i in 6 12 24 48; do
size=$((768/i))
/work/tools/mpi/gcc/openmpi/2.1.1/bin/mpirun --allow-run-as-root -np $i /work/tools/bin/ior -w -r -t 1m -b ${size}g -e -F -vv -o /scratch0/file | tee
ior-1n${i}p-${VER}.log
done
Summaruy of Read Performance(MB/sec)
| branch | thr=6 | thr=12 | thr=24 | thr=48 |
|---|---|---|---|---|
| b2_12 | 9,965 | 14,551 | 17,177 | 18,152 |
| master | 15,252 | 16,026 | 17,842 | 16,991 |
| master(pRA=off) | 10,253 | 14,489 | 17,839 | 18,658 |
pRA=off - disabling parallel readahead (llite.*.read_ahead_async_file_threshold_mb=0)