On 2017-Mar-30, at 1:22 PM, Mark Millard <markmi_at_dsl-only.net> wrote: > On 2017-Mar-29, at 8:53 AM, Brooks Davis <brooks at freebsd.org> wrote: > >> On Mon, Mar 27, 2017 at 03:25:04AM -0700, Mark Millard wrote: >>> On 2017-Mar-27, at 2:41 AM, Dimitry Andric <dim at FreeBSD.org> wrote: >>> >>>> On 26 Mar 2017, at 23:36, Mark Millard <markmi_at_dsl-only.net> wrote: >>>>> >>>>> I upgraded from llvm40 r4 to final. An interesting result was >>>>> its creation of a backup package for llvm40-4.0.0.r4: >>>>> >>>>> about 13 cpu-core-hours running pkg create >>>>> >>>>> (Remember: I've been building with WITH_DEBUG= ) Its >>>>> single-threaded status stands out via elapsed time >>>>> approximately matching. >>>>> >>>>> I'll note that it was somewhat under 6 elapsed hours for >>>>> staging to have been populated (-j4 with 4 cores present >>>>> helps for this part). >>>>> >>>>> (Of course these elapsed-time figures are rather system >>>>> dependent, although the ratio might be more stable.) >>>>> >>>>> >>>>> >>>>> Also interesting was: >>>>> >>>>> Installed packages to be REMOVED: >>>>> llvm40-4.0.0.r4 >>>>> >>>>> Number of packages to be removed: 1 >>>>> >>>>> The operation will free 49 GiB. >>>> >>>> Yes, this is big. But there is no real need to build the llvm ports >>>> with debug information, unless you want to hack on llvm itself. And >>>> in that case, you are better served by a Subversion checkout or Git >>>> clone from upstream instead. >>>> >>>> -Dimitry >>> >>> FYI: >>> >>> Historically unless something extreme like this ends up >>> involved I build everything using WITH_DEBUG= or explicit >>> -g's in order to have better information on any failure. >>> >>> This is extreme enough that next time I synchronize >>> /usr/ports and it has a devel/llvm40 update I'll >>> likely rebuild devel/llvm40 without using WITH_DEBUG= . >>> I'm more concerned with the time it takes than with >>> the file system space involved. >> >> In the case of LLVM, enabling debug builds does a LOT more than adding >> symbols. It's much more like enabling WITNESS and INVARIANTS in your >> kernel, except that the performance of the resulting binary is much >> worse than a WITNESS kernel (more like 10x slowdown). >> >> As Dimitry points out, these builds are of questionable value in ports >> so garbage collecting the knob might be the sensable thing to do. > > Sounds like the ALLOW_OPTIMIZATIONS_FOR_WITH_DEBUG technique > would not change the "WITNESS and INVARIANTS"-like part of the > issue. In fact if WITH_DEBUG= causes the cmake debug-style > llvm40 build ALLOW_OPTIMIZATIONS_FOR_WITH_DEBUG might not > make any difference: separate enforcing of lack of optimization. > > But just to see what results I've done "pkg delete llvm40" > and am doing another build with ALLOW_OPTIMIZATIONS_FOR_WITH_DEBUG= > and its supporting code in place in addition to using WITH_DEBUG= > as the type of build fro FreeBSD's viewpoint. > > If you know that the test is a waste of machine cycles, you can > let me know if you want. The experiment showed that ALLOW_OPTIMIZATIONS_FOR_WITH_DEBUG use made no difference for devel/llvm40 so devel/llvm40 itself has to change such as what Dimitry Andric reported separately as a working change to the Makefile . (ALLOW_OPTIMIZATIONS_FOR_WITH_DEBUG would still have its uses for various other ports.) === Mark Millard markmi at dsl-only.netReceived on Fri Mar 31 2017 - 00:51:48 UTC
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