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Re: [PATCH v3] coccicheck: process every source file at once

On Fri, Oct 05, 2018 at 08:39:04PM +0200, SZEDER Gábor wrote:

> > It should still be a net win, since the total CPU seems to drop by a
> > factor of 3-4.
> Well, that's true when you have unlimited resources... :)  or it's
> true even then, when I have just enough resources, but not much
> contention.  After all, Coccinelle doesn't have to parse the same
> header files over and over again.  However, on Travis CI, where who
> knows how many other build jobs are running next to our static
> analysis, it doesn't seem to be the case.
> On current master with an additional 'time' in front:
>   time make --jobs=2 coccicheck
>   <...>
>   695.70user 50.27system 6:27.88elapsed 192%CPU (0avgtext+0avgdata 91448maxresident)k
>   5976inputs+2536outputs (42major+18411888minor)pagefaults 0swaps
>   https://travis-ci.org/szeder/git/jobs/437733874#L574
> With this patch, but without -j2 to fit into 3GB:
>   960.50user 22.59system 16:23.74elapsed 99%CPU (0avgtext+0avgdata 1606156maxresident)k
>   5976inputs+1320outputs (26major+4548440minor)pagefaults 0swaps
>   https://travis-ci.org/szeder/git/jobs/437734003#L575
> Note that both the runtime and the CPU time increased. (and RSS, of
> course)

I'm not sure what to make of those results. Was the jump in CPU _caused_
by the patch, or does it independently fluctuate based on other things
happening on the Travis servers?

I.e., in the second run, do we know that the time would not have
actually been worse with the first patch?