Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi,
I ran some drbd performance tests with 'tiobench':
tiobench.pl --identifier drbd-connected --size 5000 --numruns 1 --dir
/secroot --block 4096 --threads 4
noticed the huge max latency numbers with Sequential Writes:
Unit information
================
File size = megabytes
Blk Size = bytes
Rate = megabytes per second
CPU% = percentage of CPU used during the test
Latency = milliseconds
Lat% = percent of requests that took longer than X seconds
CPU Eff = Rate divided by CPU% - throughput per cpu load
Identifier
File Size
Blk Size
Num Thr
Rate
Maximum CPU%
Avg Latency
Max Latency
Lat% >2s
Lat% >10s
CPU Eff
Raw-device
5000
4096
4
31.24
26.80%
0.364
5635.06
0.00242
0.00000
117
Drbd-disconnected
5000
4096
4
33.18
26.29%
0.319
110394.58
0.00190
0.00016
126
Drbd-connected
5000
4096
4
20.88
50.18%
0.457
135712.09
0.00110
0.00008
42
My lab setting:
* Two Linux nodes on 2.6.10_mvlcge401-pc_target-x86_pentium3-P3SMP.
* Dual-core Intel Xeon 2GHz CPU, 4GB Memory, 1Gbits/s network interface.
* 5.7GB partition on SCSI disk, ext2 file system with the "-T
largefile4" option.
* DRBD version is 0.7.11, rate=100M; protocal C; sndbuf-size 1024k.
I don't believe the disk (~50MB/s) or network may be the factors here.
You can see the big number jump even with the DRBD disconnected mode.
Any help on analyzing/identifying the problem will be greatly appreciated.
Weilin
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