Re: build times

On 10/02/2011 05:25 PM, Tom Lane wrote:
> Andrew Dunstan<andrew@dunslane.net>  writes:
>> I have been investigating some build performance issues, and trying to
>> narrow down causes of slowness, and observed an odd effect, which was
>> suggested by a huge time difference between building from git and
>> building from a tarball.
>> If I do
>>       make -C src/port all
>> and then wait 10 seconds or so and do
>>       make -j 3
>> or even just plain
>>       make
>> the build finishes much much faster (like 1m vs 5m) than if I had not
>> run the first command.
> Can't reproduce that here.  What I do notice on a Fedora 14 machine is
> that ccache seems to be enabled by default, ie you get caching even when
> you just say "gcc", and that makes a huge difference in build times.
> I see 70 seconds after "rm -rf ~/.ccache", versus 4 seconds with it
> fully populated.  Building src/port first saves nothing in either
> starting state.
>
> I wonder whether your experiments got affected by something similar.
>
>             

Yes, possibly, although SL6 (which is an RHEL clone) doesn't have ccache 
by default. I'm not sure what happened there, as now I can't reproduce 
it either.

Sorry for the noise.

cheers

andrew