Re: 2.5.8 final - another data point

J Sloan (joe@tmsusa.com)
Mon, 15 Apr 2002 01:14:36 -0700


Andrew Morton wrote:

>It's not related to BIO. dbench is all about higher-level
>memory management, high-level IO scheduling and butterfly
>wings.
>
Yes, no doubt and a lot of other deep magic
which is only dimly perceived by the likes
of yours truly....

>>
>>Throughput 150.159 MB/sec (NB=187.698 MB/sec 1501.59 MBit/sec) 8 procs
>>Throughput 7.25691 MB/sec (NB=9.07113 MB/sec 72.5691 MBit/sec) 16 procs
>>Throughput 6.36332 MB/sec (NB=7.95415 MB/sec 63.6332 MBit/sec) 32 procs
>>
>
>It's obviously fallen over some cliff. Conceivably the larger readahead
>window causes this. How much memory does the machine have?
>
The box has 512 MB RAM -

>`dbench 64'
>on a 512 meg setup certainly causes readahead thrashing. You can
>stick a `printk("ouch");' into handle_ra_thrashing() and watch it...
>
hmm - OK, will try that -

Just for giggles, same machine with 2.4.19-pre4-ac4 -

Throughput 150.979 MB/sec (NB=188.723 MB/sec 1509.79 MBit/sec) 1 procs
Throughput 150.796 MB/sec (NB=188.496 MB/sec 1507.96 MBit/sec) 2 procs
Throughput 151.185 MB/sec (NB=188.982 MB/sec 1511.85 MBit/sec) 4 procs
Throughput 141.255 MB/sec (NB=176.568 MB/sec 1412.55 MBit/sec) 8 procs
Throughput 105.066 MB/sec (NB=131.332 MB/sec 1050.66 MBit/sec) 16 procs
Throughput 69.3542 MB/sec (NB=86.6928 MB/sec 693.542 MBit/sec) 32 procs
Throughput 32.4904 MB/sec (NB=40.613 MB/sec 324.904 MBit/sec) 64 procs
Throughput 30.4824 MB/sec (NB=38.103 MB/sec 304.824 MBit/sec) 80 procs
Throughput 19.0265 MB/sec (NB=23.7832 MB/sec 190.265 MBit/sec) 128 procs

>
>
>Patience. 2.5.later-on will perform well. :)
>
Oh, yes -

It's already quite usable for some workloads, and the
latency for workstation use is quite good - I am looking
forward to the maturation of this diamond in the rough

:-)

Joe

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