increasing blocksizes decrease performance in Gbit

From: Zoltan Bogdan (zoltan.bogdan@t-online.de)
Date: Thu Oct 17 2002 - 07:38:59 EST


Hi,

does anyone know about the performace impact whereabouts of different
blocksizes?

I'm using kernel 2.4.18 on a machine with 512MB Ram and two 3Ware
Escalade
7850 controllers with an 8-Disk (hardware- )RAID 5 array on each.

A softraid 0 Array spans those two Raidarrays.

While doing some benchmarks over Gbit Network I experianced the
following:
  
Block | Read Lin | Read Rnd | Write Lin
 kB | MB/sec | MB/sec | MB/sec
------+----------+----------+-----------
   16 | 25.9 | 3.3 | 12.1
   32 | 31.5 | 6.6 | 17.8
  256 | 15.4 | 13.2 | 21.3
 1024 | 13.7 | 20.8 | 21.4

Any clue why the value for linear read decreases when the Blocksizes get
higher?

I thought the contrary to be true.

I apologize if my question I to off topic.

Thanks
z

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