Hi all,
I have a pvfs2-2.8.1 with 4 DS. "BMIModules" is set to "bmi_ib". I
use simple-tripe mode with stipe-size =1MB.
8 client nodes mount pvfs2, and I use iozone to measure the write
throughput, with each client node runs one iozone process.
Each process writes 1GB file with block size = 4MB.
I got the following results:
Test running:
Children see throughput for 8 initial writers = 98513.53 KB/sec
Min throughput per process = 11406.64 KB/sec
Max throughput per process = 12642.13 KB/sec
Avg throughput per process = 12314.19 KB/sec
Min xfer = 946176.00 KB
CPU Utilization: Wall time 86.492 CPU time 6.355 CPU
utilization 7.35 %
Test running:
Children see throughput for 8 rewriters = 2499467.09 KB/sec
Min throughput per process = 289479.62 KB/sec
Max throughput per process = 321507.38 KB/sec
Avg throughput per process = 312433.39 KB/sec
Min xfer = 946176.00 KB
CPU utilization: Wall time 3.272 CPU time 5.990 CPU
utilization 183.08 %
We can see the "initial write" gets very low throughput, while the
"rewrite" gives very high bandwidth.
My questions are:
1. Why 8 client nodes as a whole get low throughput?
2. Why at "rewrite" phase, the write bandwidth boosts ?
-Neutron
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