Also seeing 2 x quad-core system slower that 2 x dual core

Claus Guttesen kometen at
Fri Dec 7 05:41:50 PST 2007

> Just as a followup to this - I soent some time going through all
> the suggestions and advice that people gave me regarding this problem.
> It turns out that the newer servers shipped by HP have different cache
> settings to the older ones on their RAID controllers, plus I get very
> different results from my benchmarks depending on how long the machines
> have been booted for and what activity has occurred on them (probably due to
> things ending up in cache).

What settings are there on the cache? I have a DL 380 G5 with 2 x
dual-core woodcrest and 512 MB BB cache running as a db-server
(postgresql) and two DL 360 G5 with with 2 x 4-core and 256 MB BB
cache running as web-servers.

> Upshot - if the machines are configured identically, and an identical install
> is made and an identical test doen then we get identical performance as
> expected.
> Part of the reason for posting this though is that a lot of people have bbeen
> worrying about 8x CPU performance, and this thread won't have helped. So
> I wanted to say that now I am convinced that (for my workload) these machines
> are fine. To the point where I have installed 7.0-BETA4 on the ten new
> 8 core servers for a very large load on th webfarm this morning. I'm pleased
> toio say that it went off perfectly, the servers took the load and we had
> no problems at all. We are running CGI scripts against mySQL under apache22
> basically - which is a pretty common thing to do. Ia m using ULE and tthe
> amd64 version of the OS.

I will second this even though I do not have hard facts to base this
assumption on. I have - as mentioned above - two web-servers running
7.0 beta 2 on a 8-core and is satisfied with the performance. But my
only comparison are two 2 x dual-core opterons (4-way) where the
8-core handles approx. twice as much load. But maby I should expect
2.5 as much performance since the quad-core is a newer cpu and the
opterons are getting two years old.

I also upgraded our db-server from 6.2 RC1 to 7.0 beta 3 on our DL 380
G5 (4-way) because the server was getting constrained on ressources. I
could either replace my 10K rpm drives (in raid 1+0) with 15K ditto
which would require a downtime which we could not afford at this time
or I could upgrade from 6.2 to 7.0. The upgrade took 10 min. Kernel
and userland had all ready been compiled on the web-server. The
upgrade was worthwhile and the db-server is performing better. On
Sunday I will have some load-numbers and post them on Monday.


When lenity and cruelty play for a kingdom,
the gentlest gamester is the soonest winner.


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