Date: Tue, 5 Oct 2021 22:04:32 +0200 From: Matthias Andree <mandree@FreeBSD.org> To: Piotr Kubaj <pkubaj@anongoth.pl> Cc: ports-committers@freebsd.org, dev-commits-ports-all@freebsd.org, dev-commits-ports-main@freebsd.org, Mathieu Arnold <mat@freebsd.org> Subject: Re: git: fb5f03a87cf4 - main - Mk/bsd.lto.mk: add global LTO support for ports Message-ID: <44365771-0a1d-7bcb-2cb6-85f592624a3b@FreeBSD.org> In-Reply-To: <YVyCEPlZJvdce4Ak@KGPE-D16> References: <202109301834.18UIYKrL013410@gitrepo.freebsd.org> <20211004133056.z7e2iyrhlwprvvvp@aching.in.mat.cc> <YVx84wGVlSr2nmBX@KGPE-D16> <20211005163152.gv2vwvg4nuqwga7q@aching.in.mat.cc> <YVyCEPlZJvdce4Ak@KGPE-D16>
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Am 05.10.21 um 18:49 schrieb Piotr Kubaj: > On 21-10-05 18:31:52, Mathieu Arnold wrote: >> On Tue, Oct 05, 2021 at 06:27:15PM +0200, Piotr Kubaj wrote: >>> On 21-10-04 15:30:56, Mathieu Arnold wrote: >>>> On Thu, Sep 30, 2021 at 06:34:20PM +0000, Piotr Kubaj wrote: >>>>> The branch main has been updated by pkubaj: >>>>> >>>>> URL: https://cgit.FreeBSD.org/ports/commit/?id=fb5f03a87cf432751fae1f0ae7f29c9d4fc65917 >>>>> >>>>> commit fb5f03a87cf432751fae1f0ae7f29c9d4fc65917 >>>>> Author: Piotr Kubaj <pkubaj@FreeBSD.org> >>>>> AuthorDate: 2021-09-30 18:27:50 +0000 >>>>> Commit: Piotr Kubaj <pkubaj@FreeBSD.org> >>>>> CommitDate: 2021-09-30 18:27:50 +0000 >>>>> >>>>> Mk/bsd.lto.mk: add global LTO support for ports >>>>> >>>>> It's well known that LTO provides both performance and size benefits for >>>>> binaries. >>>>> >>>>> Add preliminary, opt-in support for global LTO enforcement to ports. Ports that >>>>> provide LTO option on their own and the ones that don't work with LTO will need >>>>> to set LTO_UNSAFE in the future. >>>>> >>>>> PR: 258536 >>>> >>>> Not to be picky about approval and all, but this was added to the >>>> framework, and the framework is maintained by portmgr. When you want to >>>> add something to it, you must consult with portmgr before anything gets >>>> committed. >>>> >>>> In that case, we would have told you not to do it this way, but to make >>>> this a Mk/Uses/lto.mk. >>>> >>>> So please, turn this into a USES=lto. >>> >>> I did consult, but no one replied. >> >> There is absolutely no maintainer timeout for the framework, you cannot >> just add code there without explicit approval. > > And this is a port of a bigger issue, where portmgr ignores emails until numerously asked for (if one is lucky). > As one of users wrote in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=251117, for which portmgr is assigned, "portmgr@ more and more feels to me like a black hole, or /dev/null: Anything sent there seems to disappear without effect." > > Since it was a change that doesn't change anything out-of-the-box, I decided to commit it. > >> >>> IMO adding it to USES is not a good idea, since USES are supposed to be used per port and my idea was to force LTO for all ports, same way that SSP already does. >> >> All I see in the patch is a USE_LTO knob, and a LTO_UNSAFE one, without >> any documentation of what it is for, what it does, what it might do, >> what it is about, or anything else. > Neither has SSP, I don't see any documentation for it (including commiter handbook which has just one line regarding USES=kmod at https://docs.freebsd.org/en/books/porters-handbook/book/#uses-kmod). Piotr, While I sympathize with your findings about portmgr@ 'responsiveness' having had my shares of ignores and brushes, I would tend to agree that we should not add undocumented knobs anywhere, so: 1. please add documentation including motivation 2. I wonder about a deployment plan. LTO linking incurs several issues, such as memory use, disk-space use with fat objects, and concurrency issues that cause a massive prolongation of linking, which I've often seen to run a single thread. I think these items need consideration. Other than that, I appreciate the initiative to support LTO inside the framework, to avoid each and every port implementing it by itself, which will cause a maintenance mess down the road. Regards, Matthias
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