Re: [gentoo-user] Re: Simultaneously emerging multiple packages with same dependencies

[YoYo Siska <yoyo@gl.ksp.sk>]

On Thu, Jan 27, 2011 at 08:18:34PM +0100, J. Roeleveld wrote:
> On Thursday 27 January 2011 19:56:23 Allan Gottlieb wrote:
> > On Thu, Jan 27 2011, Neil Bothwick wrote:
> > > On Thu, 27 Jan 2011 17:09:27 +0200, Nikos Chantziaras wrote:
> > >> > So on a 20 package world update, only 19 are faster while the 20th
> > >> > runs at the same speed? Where's the loss there? Even if the last were
> > >> > slower, it would be worth it.
> > >> 
> > >> Given the amount of time unpack/configure/install of most packages
> > >> needs (very short), my observation is that it would not be worth it.
> > > 
> > > Even if that were true, how much time would you have to save to justify
> > > adding -j 2 to EMERGE_DEFAULTS in make.conf?
> > > 
> > > But it's not true, large packages spend a lot of time on these phases of
> > > the install.
> > 
> > OK I'm convinced since I know that those phases do take noticeable time.
> > 
> > I have a "4" processor i7 model 620 (2 cores, doubled for
> > hyperthreading) and have set MAKEOPTS="-j5".
> > If I add -jobs=2 to EMERGE_DEFAULT_OPTS, should I lower
> > MAKEOPTS to 3 (to 4)?
> > 
> > thanks,
> > allan
> 
> You could, as if you leave it at -j5, you can end up with 2 * 5 = 10 
> processed, eg: similar as if running with MAKEOPTS="-j10"
> 
> I think the option that YoYo came with is a good compromise:
> # MAKEOPTS="-j -l5" emerge -j --load-average=5
> 
> Next time I am doing a big upgrade, I'm going to test that to see how it 
> behaves.

I was just building the whole system for my notebook in a chroot on my
desktop machine ( I use FEATURES=buildpkg to build binary packages in
the chroot on a fast desktop machine and then upgrade the notebook with
the binary packages) and I used exactly that (-j -l5 for bot make and
emerge). Can't say if it really is better or not ;) but most of the time
all four cores were busy, though sometimes I saw even 6 or 7 gcc-s
simultaneously in top ;)
emerge was running 3 to 4 jobs most of the time, sometimes dropping to 1
and once I saw it emerging about 10 parallel packages ;) (mostly small
things, which I guess were doing a lot of
unpacking/configuring/installing but almost nothing of compiling ;)


btw, just now I got this error from dev-lang/v8:

SCons error: option -j: invalid integer value: '-l4'

seems scons honors  MAKEOPTS, but doesn't understand the "loadaverage"
version (-j -l4)


yoyo