"sqlio -kR -b1024" - Reading 1-MB Block Test

Q

How to perform tests for reading 1 MB files? I want to see the impact of file size on reading files.

✍: FYIcenter.com

A

If you want to see the impact of file size on reading files, try to increase the block size from 64 KB to 1024 KB (1 MB), and keep the other options unchanged:

C:\fyicenter\SQLIO>sqlio -LS -kR -b1024 -i64 -f64 -t1 -s300

1 thread reading for 300 secs from file testfile.dat
        using 1024KB IOs over 65536KB stripes with 64 IOs per run
        affinity on cpu number 0
size of file testfile.dat needs to be: 4294967296 bytes
initialization done
CUMULATIVE DATA:
throughput metrics:
IOs/sec:    53.48
MBs/sec:    53.48
latency metrics:
Min_Latency(ms): 9
Avg_Latency(ms): 18
Max_Latency(ms): 132
histogram:
ms: 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24+
%:  0  0  0  0  0  0  0  0  0  0  1  1  7  5  6  8 14 15 11  7  7  8  3  1  6

Comparing to the previous test of reading 64-KB blocks, the throughput of reading 1024-KB blocks increased from 8.77 MBs/sec to 53.48 MBs/sec.

This tells us that this Windows environment is more efficient on reading larger files, because operating systems are usually designed to read the requested sector and many additional consecutive sectors of data from the device each time and cache them in RAM. If the next requested sector is in the cache, it will read it from the RAM instead of the device.

Of course, this caching mechanism helps more in the case of large files, because they are more likely to be stored in consecutive sectors.

 

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2019-09-04, 184👍, 0💬