[U-Boot] [PATCH] Allow for parallel builds and saved output

[Mike Frysinger]

On Monday 21 November 2011 01:28:50 Andy Fleming wrote:
> On Sun, Nov 20, 2011 at 11:15 PM, Simon Glass wrote:
> > On Sun, Nov 20, 2011 at 1:23 PM, Mike Frysinger wrote:
> >> On Thursday 03 November 2011 03:28:29 Andy Fleming wrote:
> >> 
> >> you don't need those semicolons.  also, this is not as good as it should
> >> be: if you're running 10 jobs in parallel, you fork 10, and then you
> >> wait for all of them to finish before forking another set of 10.
> >> 
> >> what you could do is something like:
> >>        JOB_IDX=0
> >>        JOB_IDX_FIRST=0
> >>        BUILD_NBUILDS=1
> >> 
> >>        ... foreach target ... ; do
> >>                build_target &
> >>                pids[$(( JOB_IDX++ ))]=$!
> >>                if [ $(( JOB_IDX - JOB_IDX_FIRST )) -ge ${BUILD_NBUILDS}
> >> ] ; then wait ${pids[$(( JOB_IDX_FIRST++ ))]}
> >>                fi
> >>        done
> >>        wait
> >> 
> >> this isn't perfect as it assumes the first job launched will always
> >> finish first, but it's a lot closer than the current code.
> > 
> > Since all the jobs are launched at the same time this is not really a
> > valid assumption is it? IMO on this point it's good enough as it is
> > for now...
> 
> Mike's idea led me to a slightly crazier one that (I think) works.
> Basically, I have each build_targets invocation create a file named
> LOG/build_N when it is done, where N is the value of TOTAL_CNT when it
> is invoked. Then I keep track of the oldest uncompleted build #. When
> we hit our build limit, the script scans for LOG/build_N, for N from
> oldest to TOTAL_CNT, and updates the count of outstanding builds, as
> appropriate (and moves the index of the oldest). If the scanning
> completes without freeing up room for another build, it waits for a
> second, and then re-scans.

sounds like it would work, but i'd want to see how much code it takes to 
actually implement this

> I tried this on my 24-core system with BUILD_NBUILDS set to 8 and
> BUILD_NCPUS set to 4, and pegged the system at ~24-30 the whole time.
> 
> I will note that it only shaved about a minute off the 15 minutes it
> took to build all 85xx.

compare to what ?  your original patch, or my tweaked version ?
-mike
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