[wellylug] CPU load

[Gordon Paynter]

Hi Brent,

A quick followup:

On Mon, 13 Dec 2004 11:51, Brent Wood wrote:
> I'm not familiar with MySQL, but I know the Postgres developers identified
> kswapd as a major load hog with s number of 2.4 installations. An upgrade
> to a 2.6 kernel supposedly fixed the problem.

It seems like it is MySQL + broken DMA doing me in.  The machine is fine for 
most uses, but simply grinds for programs that combine MySQL and intensive 
CPU load.  

Having read (very briefly) about DMA (I'm a software person), I'm a bit 
surprised that the program works at all with DMA errors.  Based on the 
syslog, it looks like the kernel (2.6.7) detects DMA failures, and since the 
whole process doesn't fall over right away, I imagine it (the kernel) falls 
back to non-DMA transfers?  Or does the data being transferred just... 
dissappear?  

The program concerned has been segfaulting later on when it performs 
calculations based on the data that was earlier stuffed into MySQL.  (This 
whole issue came up as I attempted to debug it.) I had assumed that the error 
was triggerred later, but maybe it's just bad data in the MySQL database as a 
result of DMA failures.  Anyone have any odea if that is possible?  (The same 
program runs through on other hardware.)


(I'm sick of that hardware, to be honest, the Admin has had to swap out all 
the RAM and the fans to make it work as well as it does, and we've been 
through all sorts of 2.4 and 2.6 kernels looking for stability.)

Anyway, thanks for the responses.

Gordon

PS: Brent: with the new CPU, the shuttle no longer overheats. It would have 
been continuously up sine the upgrade, except that I had guests sleeping in 
the office, so I had to shut it down once or twice.