On Thu, 28 Aug 2014, Luis R. Rodriguez wrote:
> On Thu, Apr 10, 2014 at 09:32:34PM +0200, Julia Lawall wrote: > > > > > > On Thu, 10 Apr 2014, Luis R. Rodriguez wrote: > > > > > On Thu, Apr 10, 2014 at 07:51:29PM +0200, Johannes Berg wrote: > > > > On Thu, 2014-04-10 at 10:48 -0700, Luis R. Rodriguez wrote: > > > > > > > > > You just pass it a cocci file, a target dir, and in git environments > > > > > you always want --in-place enabled. Experiments and profiling random > > > > > cocci files with the Linux kernel show that using just using number of > > > > > CPUs doesn't scale well given that lots of buckets of files don't > > > > > require > > > > > work, as such this uses 10 * number of CPUs for its number of threads. > > > > > For work that define more general ruler 3 * number of CPUs works > > > > > better, > > > > > but for smaller cocci files 3 * number of CPUs performs best right > > > > > now. > > > > > To experiment more with what's going on with the multithreading one > > > > > can enable > > > > > htop while kicking off a cocci task on the kernel, we want to keep > > > > > these CPUs busy as much as possible. > > > > > > > > That's not really a good benchmark, you want to actually check how > > > > quickly it finishes ... If you have some IO issues then just keeping the > > > > CPUs busy trying to do IO won't help at all. > > > > > > I checked the profile results, the reason the jobs finish is some threads > > > had no work or little work. Hence why I increased the number of threads, > > > depending on the context (long or short cocci expected, in backports > > > at least, the long being all cocci files in one, the short being > > > --test-cocci > > > flag to gentree.py). This wrapper uses the short assumption with 10 * > > > num_cpus > > > > > > > > Since its just a helper I toss it into the python directory but don't > > > > > install it. Hope is that we can evolve it there instead of carrying > > > > > this > > > > > helper within backports. > > > > > > > > If there's a plan to make coccinelle itself multi-threaded, what's the > > > > point? > > > > > > To be clear, Coccinelle *has* a form of multithreaded support but > > > requires manual > > > spawning of jobs with references to the max count and also the number > > > thread > > > that this new process you are spawning belongs to. There's plans to > > > consider > > > reworking things to handle all this internally but as I discussed with > > > Julia > > > the changes required would require some structural changes, and as such we > > > need to live with this for a bit longer. I need to use Coccinelle daily > > > now, > > > so figured I'd punt this out there in case others might make use of it. > > > > I agree with Luis. Multithreading inside Coccinelle is currently a > > priority task, but not a highest priority one. > > Folks, anyone object to merging pycocci in the meantime? I keep using it > outside > of backports and it does what I think most kernel developers expect. This > would > be until we get proper parallelism support in place. Merge away... julia -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
