Em 20/04/2013 09:09, Tobi Oetiker escreveu:

hi daniel

On 19.04.2013, at 16:42, Daniel Hilst Selli <danielhilst@gmail.com> wrote:

...

AFAIK, major page faults are generated when data that is not yet present on RAM is loaded from disk, but in this case data is being write do disk, I can't see how writes can generate faults, but still, it seems that is happening, ... !?

rrdtool changes just few bytes in the rrf file with each update

the OS though can only write a complete block of data to disk.

so when you write a byte to a file, the OS has to first fetch the block, modify the byte and write the block back

that is why rrdtool benefits greatly from more RAM as it can hold mor blocks in RAM and does not have to read them first.

cheers tobi

Thanks Tobi, I had no idea about this read/update/write process, Now I know how to improve the performance of my collectd+rrdtool stuff, Cheers