On 8/2/19 11:15 AM, Jan Hubicka wrote: >> On Fri, Aug 2, 2019 at 10:50 AM Jakub Jelinek <ja...@redhat.com> wrote: >>> >>> On Fri, Aug 02, 2019 at 10:47:10AM +0200, Martin Liška wrote: >>>>> Can you strace if other fds are opened and not closed in the spot you had >>>>> it >>>>> before? Advantage of doing it there is that it will not be done for all >>>>> the >>>>> -E/-S/-c compilations when the linker is not spawned. >>>> >>>> I've used the same trick which you used and I'm attaching the output. >>>> I believe it's fine, I can't see any opened fd by GCC. >>> >>> LGTM. >>
Hi. >> Btw, we discussed yesterday on the phone and the conclusion was to >> make -flto auto-detect a job-server (but not fall back to # of threads) >> and add -flto=auto to auto-detect a job-server and fall back to # of threads. >> That basically makes -flto=jobserver the default behavior which means >> we should document -flto=1 as a way to override jobserver detection. > > And concerning to the yesterday discussion, my preference would still be > -flto to first try presence of jobserver and default to number of > threads otherwise. It seems like user friendly default to me and other > tools with reasonable parallelism support usually behaves this way, too. I also like the default as Honza defined. > > Sure one can use -flto=auto everywhere but then one needs to use > different options for differnt compilers. It would be nice to make > -flto to do right hting for majority of users including those like me > who cut&paste command lines from Make output and execute them by hand. Note that our ambition is to ideally backport the patches to our gcc9 package. The auto-detection of job-server with -flto is a behavior change that will happen in the gcc9 package. To be honest I don't like the invention of 'auto' value for -flto command. That would be useful just for gcc9 right now :/ Martin > > The fork bombing is IMO relatively rare and it was not what Jakub ran > into (it was broken jobserv detection). > After all whole distro built with Martin's orriginal approach of > -flto=<nthreads> which forkbombs on every possible occasion. > > Said that, I could live with more conservative defaults. > Honza >
