In response to "Anders Boström" <[EMAIL PROTECTED]>:

> >>>>> "BM" == Bill Moran <[EMAIL PROTECTED]> writes:
> 
>  BM> In response to "Anders Boström" <[EMAIL PROTECTED]>:
>  >> >> gzip on this computer, on one CPU, reach about 18 Mbyte/s. bacula with
>  >> >> gzip only reach ~7.7 Mbyte/s. This leads me to believe that there are
>  >> >> room for improvement.
>  >> 
>  BM> Again, the story changes.  Above, you indicate that tar+gzip ran about
>  BM> 15% faster than bacula with gzip, which seems reasonable.  Now you're
>  BM> saying that gzip is ~twice as fast as Bacula + gzip.  Where did this new
>  BM> number come from?  Are you taking in to account networking on this new
>  BM> test?
>  >> 
>  >> If I state that "gzip on this computer, on one CPU, reach about 18
>  >> Mbyte/s", I mean just that, nothing else. To clarify, this means that
>  >> pure gzip-performance on this computer, using just one gzip-process,
>  >> is 18 Mbyte/s.
> 
>  BM> If you would be kind enough to humor me ...
> 
>  BM> Please create a file (or use an existing one) of notable size: few
>  BM> hundred meg.
> 
>  BM> Put the file on the disk and time gzipping it.  Run it 5 times.
> 
>  BM> Create a memory filesystem and repeate the gzip tests with the
>  BM> file living on the mfs and the gzipped target existing on the mfs.
> 
>  BM> I have a suspicion that your drives are the limiting factor in this.
>  BM> The above tests should confirm or deny that theory.
> 
> I've already done this, but did it again. The results are the same,
> disc and tmpfs gives the same results, about 18 Mbyte/s. And I would
> have been *very* surprised if they had differed, as the disc-tests
> are running out of memory in test 2-5 (due to caching).

If the system is caching the entire write operation in RAM, then you're
set up for a major disaster some day.

Even if there's enough RAM to cache the read op, the write op will
ALWAYS require disk writes.  If those two operations are taking the
same amount of time, then either you're testing wrong, or something
is really weird with your setup, or you have the fastest hard drives
on this planet.

Additionally, the point was to _not_ allow it to use cache for the disk
ops, which I didn't communicate clearly -- my apologies.

-- 
Bill Moran
Collaborative Fusion Inc.

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