Re: high load, no bottleneck

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

Edgar Fuß <ef%math.uni-bonn.de@localhost> wrote:

> How often do these log flushes occur?

On a 6.1 kernel with RAIDOUTSTANDING=800 and -o log. Stress test raises load
to around 10.
 
> During the stess phase, what does
>       iostat -D -x -w 1
> show for the raid and for the components, especially in the time column?

Here is an excerpt:
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.00     0.00      13.74     27   0.00     0.36
wd1          0.00      0   0.00     0.00      13.74     27   0.00     0.36
raid1        0.00      0   0.00     0.00      20.61     18   0.00     0.36
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.06     0.00      12.70    306   0.06     3.80
wd1          0.00      0   0.14     0.00      12.70    306   0.14     3.80
raid1        0.00      0   0.14     0.00      18.51    210   0.14     3.80
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.04     0.00      13.53    285   0.04     3.77
wd1          0.00      0   0.04     0.00      13.53    285   0.04     3.77
raid1        0.00      0   0.05     0.00      20.18    191   0.05     3.77
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.04     0.00      13.34    304   0.04     3.96
wd1         16.00      1   0.04     0.02      13.34    304   0.04     3.96
raid1       16.00      1   0.05     0.02      20.28    200   0.05     3.96
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.06     0.00      12.97    242   0.06     3.06
wd1          0.00      0   0.13     0.00      12.97    242   0.13     3.06
raid1        0.00      0   0.13     0.00      19.42    161   0.13     3.06


> During the stress, do you see small synchronous writes in NFS traffic?

Output of your first script:
2908 getattr
1140 lookup
 969 access
 273 fsstat
 195 write
 145 commit
 110 create
 102 setattr
  94 remove
  23 read

Output of your second script:
 167 549 unstable
  28 549 filesync

And here is the iostat without -o log (load barely raise to 1)

device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.00     0.00      14.86     48   0.00     0.69
wd1          0.00      0   0.00     0.00      14.86     48   0.00     0.69
raid1        0.00      0   0.00     0.00      22.30     32   0.00     0.69
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.07     0.00       7.75    227   0.07     1.72
wd1          0.00      0   0.06     0.00       7.75    227   0.06     1.72
raid1        0.00      0   0.09     0.00       7.85    224   0.09     1.72
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.01     0.00      14.08     50   0.01     0.69
wd1          2.00      1   0.01     0.00      14.08     50   0.01     0.69
raid1        2.00      1   0.02     0.00      32.64     22   0.02     0.69
device  read KB/t    r/s   time     MB/s write KB/t    w/s   time     MB/s
wd0          0.00      0   0.00     0.00      10.40     20   0.00     0.20
wd1         16.00      1   0.05     0.02      10.40     20   0.05     0.20
raid1       16.00      1   0.05     0.02      14.86     14   0.05     0.20


-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost