optimized script [Was: ARM defconfig files]
olof at lixom.net
Wed Jul 14 04:04:02 EST 2010
On Tue, Jul 13, 2010 at 10:07:05AM +0200, Uwe Kleine-König wrote:
> On Tue, Jul 13, 2010 at 09:07:41AM +0200, Uwe Kleine-König wrote:
> > Hi
> > On Mon, Jul 12, 2010 at 01:50:47PM -0600, Grant Likely wrote:
> > > On Mon, Jul 12, 2010 at 1:34 PM, Linus Torvalds
> > > <torvalds at linux-foundation.org> wrote:
> > > > On Mon, Jul 12, 2010 at 12:17 PM, Nicolas Pitre <nico at fluxnic.net> wrote:
> > > >> I think Uwe could provide his script and add it to the kernel tree.
> > > >> Then all architectures could benefit from it. Having the defconfig
> > > >> files contain only those options which are different from the defaults
> > > >> is certainly more readable, even on x86.
> > > >
> > > > Quite possible. But maintainers would need to be on the lookout of
> > > > people actually using the script, and refusing to apply patches that
> > > > re-introduce the whole big thing.
> > >
> > > I can (partially) speak for powerpc. If ARM uses this approach, then
> > > I think we can do the same. After the defconfigs are trimmed, I
> > > certainly won't pick up any more full defconfigs.
> > I just restarted my script on the powerpc defconfigs basing on rc5, I
> > assume they complete in a few days time.
> So Stephen was faster than me. I don't know yet how he optimised my
> script, meanwhile I put some efforts into it, too by just checking lines
> that match "^(# )?CONFIG_".
> Find it attached.
> I will start to reduce the remaining configs (i.e. all but arm and
I added just a simple heuristic: If I could remove a line, I attempted
to remove twice the amount next time around (and fall back to 1 if it failed).
I.e. main loop:
i = 0
lines = 1
while i < len(config):
print 'test for %r + %d' % (config[i], lines)
defconfig = open(defconfig_src, 'w')
defconfig.writelines(config[i + lines:])
subprocess.check_call(['make', '-s', 'ARCH=%s' % arch, target])
if os.stat('.config').st_size == config_size and list(open('.config')) == origconfig:
lines *= 2
if lines > 1:
lines = 1
i += 1
I didn't measure what the actual improvement was, but I saw a fair amount
of 2/4/8-attempts passing, so I let it run. Stephen beat me to posting
the resulting patch though. :P
While this script is great, it is somewhat painful to run given that it
attempts one config per line. Even on a fast machine that tends to take
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