RE: [gentoo-user] Controlling emerges

[Laurence Perkins <lperkins@openeye.net>]

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> From: Alan McKinnon alan.mckinnon@gmail.com<mailto:alan.mckinnon@gmail.com>
> Sent: Monday, September 18, 2023 9:13 AM
> To: gentoo-user@lists.gentoo.org<mailto:gentoo-user@lists.gentoo.org>
> Subject: Re: [gentoo-user] Controlling emerges
>
>
>
> On Mon, Sep 18, 2023 at 6:03 PM Peter Humphrey peter@prh.myzen.co.uk<mailto:peter@prh.myzen.co.uk> wrote:
> On Monday, 18 September 2023 14:48:46 BST Alan McKinnon wrote:
> > On Mon, Sep 18, 2023 at 3:44 PM Peter Humphrey peter@prh.myzen.co.uk<mailto:peter@prh.myzen.co.uk>
> >
> > wrote:
> > > It may be less complex than you think, Jack. I envisage a package being
> > > marked
> > > as solitary, and when portage reaches that package, it waits until all
> > > current
> > > jobs have finished, then it starts the solitary package with the
> > > environment
> > > specified for it, and it doesn't start the next one until that one has
> > > finished.
> > > The dependency calculation shouldn't need to be changed.
> > >
> > > It seems simple the way I see it.
> >
> > How does that improve emerge performance overall?
>
> By allocating all the system resources to huge packages while not flooding the
> system with lesser ones. For example, I can set -j20 for webkit-gtk today
> without overflowing the 64GB RAM, and still have 4 CPU threads available to
> other tasks. The change I've proposed should make the whole operation more
> efficient overall and take less time.
>
> As things stand today, I have to make do with -j12 or so, wasting time and
> resources. I have load-average set at 32, so if I were to set -j20 generally
> I'd run out of RAM in no time. I've had many instances of packages failing to
> compile in a large update, but going just fine on their own; and I've had
> mysterious operational errors resulting, I suspect, from otherwise undetected
> miscompilation.
>
> Previous threads have more detail of what I've tried already.
>
> I did read all those but no matter how you move things around you still have only X resources available all the time.
> Whether you just let emerge do it's thing or try get it to do big packages on their own, everything is still going to use the same number of cpu cycles overall and you will save nothing.
>
> If webkit-gtk is the only big package, have you considered:
>
> emerge -1v webkit-gtk && emerge -avuND @world?
>
>
> What you have is not a portage problem. It is a orthodox parallelism problem, and I think you are thinking your constraint is unique in the work - it isn't.
> With parallelism, trying to fiddle single nodes to improve things overall never really works out.
>
> Just my $0.02
>
>
> Alan
>
> --
> Alan McKinnon
> alan dot mckinnon at gmail dot com
>

Note that on my systems I just make heavy use of the various load-average limiting options and as long as two of the big packages don't start within seconds of each other it does a pretty good job of letting them run by themselves.

If things do get in a snarl, you can always use kill -18/19 to suspend a few compile jobs until the system stops thrashing and resume them as capacity permits.

LMP

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