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Re: GCC 4.1: Buildable on GHz machines only?
I have to agree with Richard's assessment, gcc is currently on the verge of being
unusable in many instances.
If you have a lot of software to build and have to do complete rebuilds it's painful,
the binutils guys have a 3x speedup patch coming up, but every time there is a speedup
it gets eaten up.
gcc seem's to be moving more and more data around and does more and more temporary
allocations of huge chunks of memory. Sometimes a concearn pop's up and some 5 to
10 percent is gained only to be lost again.
My opinion on the point is that if there was a 100% speedup of gcc it would be very good
but not enough since it has slowed down so much mainly from memory usage.
I used to do kernel compiles in an hour or two on a pentium laptop, and now I can
forget it since it's memory is soon exhausted and it goes into swap.
I have never done any 'memory profiling' but I think it might be time to give it a
shot, does anybody have any hints on how to go about something like this ?
It should be enough to have a look at the places where were searching for information
that we already have had, or to make any kind of search more efficient if possible.
Perhaps it's possible to graft some kind of indexing scheme on the worst offenders,
so that some O(n^2) can get to O(1 ) or something.
The main problem seem's to be that almost any efforts to point out a single scapegoat
have not been very successful.
/ regards, Lars Segerlund.
On Thu, 28 Apr 2005 14:24:11 +0100
Richard Earnshaw <rearnsha@gcc.gnu.org> wrote:
> On Wed, 2005-04-27 at 20:57, Steven Bosscher wrote:
> > On Wednesday 27 April 2005 17:45, Matt Thomas wrote:
> > > > The features under discussion are new, they didn't exist before.
> > >
> > > And because they never existed before, their cost for older platforms
> > > may not have been correctly assessed.
> >
> > If someone had cared about them, it would have been noticed earlier.
> > But since _nobody_ has complained before you, I guess we can conclude
> > that by far the majority if GCC users are quite happy with the cost
> > assesments that were made.
>
> This is false. I've been complaining (at various levels of volume) ever
> since we switched to using the garbage collector.[1]
>
> R.
>
> [1] I don't think the Garbage Collector is the only source of slowdown.
> It was just the change that tipped the balance from not-very good to
> insane. Unfortunately, things have continued to go down-hill from
> there.