Modifying Samba to skip file system reads for IOZONE READ andREREAD

[Jeremy Allison]

On Fri, Oct 28, 2005 at 09:06:28PM -0500, Iozone wrote:

>    I forgot to mention the side-effect of the release of the hack.
> 
>    With the hack anyone could create a system that has a bogus
>    performance advantage.
> 
>    So.... I had to change Iozone to make sure that this hack
>    will not work.  The change was to alter the pattern used
>    with each revision of Iozone. Cool... problem solved.
>    BUT, it has an unfortunate side-effect on Iozone's functionality !
> 
>    Before this hack became available, Iozone users could
>    create data sets, store them for as long as they wished,
>    upgrade to new versions of Iozone and then continue
>    to use their old data sets.  Well, that's gone now.  Now
>    the user will be forced to create new data sets, anytime
>    they upgrade their version of Iozone.   A very unfortunate
>    side effect of release the hack, but alas, now mandatory.
>    (That 2 pedabyte file, that you were using for test, well, you
>    get to re-create it now) Arrrrgh....
> 
>    I prefer synergy, not tossing out hand grenades and watching
>    the fireworks. In this case, the users just lost a feature :-(

Well I think that's a shame. Look, there are always silly hacks that
people can do to 'fix' performance for a particular benchmark.

Throwing away a useful feature because someone posted some test
code is (IMHO) an over-reaction and the way you describe it here
"unfortunate...alas, now mandatory" is the sign of someone not
thinking clearly about this.

By all means add this as an option (even the default if you wish)
but at least allow people to select the old behaviour. If you
caused me to have to regenerate a 2 petabyte file each time I
did a test on server code I *know* is clean I'd be quite cross
with you.

Jeremy