Why does using threads not speed up things?

[Franz GEIGER]

This question really was not very precise. Sorry abaout that, stupid me.

Source was on a machine in the LAN, destination on the local machine (drive
D:).

Singlethreaded: Scanning the directory tree on the machine in the LAN took
1300 seconds, 600 secs for the local drive.
Multithreaded: This was in total 300 secs faster, which means, that 50% of
the "local job" were done in parallel to the "LAN job". Now that's really
not so bad, is it?

Thanks for your quick reply and sorry not being that precise.

Best regards
Franz

"Franz GEIGER" <fgeiger at datec.at> wrote in message
news:94oob9$ahq$1 at newsreaderg1.core.theplanet.net...
>
> I wrote a file synchronizer, which copies newer files to a backup
> destination and there deletes files that don't exist anymore on the
source.
> The synch source and the synch destination are connected by a LAN. So I
> thought it would be a good idea to scan the source and the destination in
> parallel, using two threads. I expected a performance gain of let's say 30
> %.
>
> So I did a few tests and wrote a sample programm that gathers file names.
It
> does this in 2 tasks: Task 1 gathers the file names on the source, task 2
on
> the destination. To be able to compare this version with the one is used
> until now, I did it that way too: First scan the source, then scan the
> destination. I called the former multithreaded version and the latter
> singlethreaded version.
>
> The singlethreaded version took 1900 seconds to execute, the multithreaded
> version took 1600 seconds. The gain is 300 seconds, which is about 15 %
> faster than the singlethreaded version.
>
> If source and destination lies on the same machine, there is no
significant
> difference in performance.
>
> As I said I'd expected more, because there is a lot of slow disk I/O
> involved and data transfer over a 10MBit section of our LAN. Or did I miss
> something?
>
> Best regards
> Franz GEIGER
>
>
>
>