2022q2/gcc.adoc: Add warning about LTO #489

lsalvadore · 2022-07-14T14:04:06Z

Warn users about the amount of ram and time needed to build GCC with
LTO_BOOTSTRAP enabled.

Reviewed by: gerald

Warn users about the amount of ram and time needed to build GCC with LTO_BOOTSTRAP enabled. Reviewed by: gerald

pauamma · 2022-07-14T17:36:06Z

2022q2/gcc.adoc

@@ -12,7 +12,7 @@ Contact: Piotr Kubaj <pkubaj@FreeBSD.org>
 * salvadore@ worked on the upgrade of GCC_DEFAULT in Mk/bsd.default-versions.mk from 10 to 11, opening bug reports based on antoine@'s exp-runs and fixing some: many thanks to all those that helped with this task. The GCC_DEFAULT update from GCC 10 to GCC 11 has now been committed by gerald@ and happened in time for the next quarterly branch.
   link:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258378[https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258378]

- * pkubaj@ switched GCC bootstrapping to use Link Time Optimization for GCC itself for GCC 11 and newer.
+ * pkubaj@ switched GCC bootstrapping to use Link Time Optimization for GCC itself for GCC 11 and newer by introducing a new option enabled by default. Building with LTO_BOOTSTRAP enabled requires significant amounts of memory and time. Consider disabling it in favor of STANDARD_BOOTSTRAP (or disabling BOOTSTRAP altogether) in case that is a problem.


Do you have a specific figure or a range for memory needed, eg is it 4GB, 64 GB, or 1 TB?

I have some figures in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=264949, in particular https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=264949#c17 . However, I think it is better to keep the statement general as:

it regards 5 different ports, with different statistics;

memory consumption depends on many different things. For example, are we building from ports or with poudriere? If we are using poudriere, how is USE_TMPFS defined? What about the machine architecture?

I still think some rough figures would help a reader decide whether it's worth trying at all, or is it nearly certain that the attempt will run out of memory after wasting 12 hours on say, an 8GB laptop. Or failing that, a link to that information.

I have added some figures, let me know if it is better.

Thanks.

That works for me.

Suggested by: pauamma

PR: 265254

lsalvadore · 2022-07-16T22:47:36Z

I am still working on it, please wait to merge.

pauamma · 2022-07-17T09:41:55Z

2022q2/gcc.adoc

@@ -12,7 +12,7 @@ Contact: Piotr Kubaj <pkubaj@FreeBSD.org>
 * salvadore@ worked on the upgrade of GCC_DEFAULT in Mk/bsd.default-versions.mk from 10 to 11, opening bug reports based on antoine@'s exp-runs and fixing some: many thanks to all those that helped with this task. The GCC_DEFAULT update from GCC 10 to GCC 11 has now been committed by gerald@ and happened in time for the next quarterly branch.
   link:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258378[https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258378]

- * pkubaj@ switched GCC bootstrapping to use Link Time Optimization for GCC itself for GCC 11 and newer by introducing a new option enabled by default. Building with LTO_BOOTSTRAP enabled requires significant amounts of memory and time. Consider disabling it in favor of STANDARD_BOOTSTRAP (or disabling BOOTSTRAP altogether) in case that is a problem.
+ * pkubaj@ switched GCC bootstrapping to use Link Time Optimization for GCC itself for GCC 11 and newer by introducing a new option enabled by default. Building with LTO_BOOTSTRAP enabled requires significant amounts of memory and time. How much resources are actually needed depends on your configuration (e.g. are you building from ports or with poudriere? What is your architecture?). To give an idea, link:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=264949#c17[a user reported that he needed 5 GiB of tmpfs]. Consider disabling LTO_BOOTSTRAP in favor of STANDARD_BOOTSTRAP (or disabling BOOTSTRAP altogether) in case that is a problem.


s/a user reported that he needed/a user reported needing/

pauamma · 2022-07-17T09:47:20Z

2022q2/gcc.adoc

@@ -12,7 +12,7 @@ Contact: Piotr Kubaj <pkubaj@FreeBSD.org>
 * salvadore@ worked on the upgrade of GCC_DEFAULT in Mk/bsd.default-versions.mk from 10 to 11, opening bug reports based on antoine@'s exp-runs and fixing some: many thanks to all those that helped with this task. The GCC_DEFAULT update from GCC 10 to GCC 11 has now been committed by gerald@ and happened in time for the next quarterly branch.
   link:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258378[https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258378]

- * pkubaj@ switched GCC bootstrapping to use Link Time Optimization for GCC itself for GCC 11 and newer by introducing a new option enabled by default. Building with LTO_BOOTSTRAP enabled requires significant amounts of memory and time. How much resources are actually needed depends on your configuration (e.g. are you building from ports or with poudriere? What is your architecture?). To give an idea, link:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=264949#c17[a user reported that he needed 5 GiB of tmpfs]. Consider disabling LTO_BOOTSTRAP in favor of STANDARD_BOOTSTRAP (or disabling BOOTSTRAP altogether) in case that is a problem.
+ * pkubaj@ switched GCC bootstrapping to use Link Time Optimization for GCC itself for GCC 11 and newer by introducing a new option enabled by default. Building with LTO_BOOTSTRAP enabled requires significant amounts of memory and time. How much resources are actually needed depends on your configuration (e.g. are you building from ports or with poudriere? What is your architecture?). To give an idea, link:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=264949#c17[a user reported that he needed 5 GiB of tmpfs], while link:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=265254#c2[another one estimated he would need about 130GB of memory for a successful build]. Consider disabling LTO_BOOTSTRAP in favor of STANDARD_BOOTSTRAP (or disabling BOOTSTRAP altogether) in case that is a problem.


s/another one estimated he would need/another estimated they would need/

Is the use of singular they really needed here? While I am not giving the name of the reporter, the reporter's identity is well known, I don't think this case needs a gender neutral form.

Moreover, if gender neutrality is needed, I usually prefer to use passive form if possible (in this case I would use "but in a different case it has also been estimated that 130GB of memory would be needed for a successful build"), but this might be because I am not a native English speaker and I will not insist if you confirm that singular they is better.

Anyway, I might need to remove the reference to this PR as this might be related to a bug instead of expected behavior, so it is not much important, at least for now.

Is the use of singular they really needed here? While I am not giving the name of the reporter, the reporter's identity is well known, I don't think this case needs a gender neutral form.

Fair question. I tend to err on the side of caution and use gender-neutral pronouns unless I know the person's preference, as the gender implied by the first name isn't 100% conclusive, non-binary people being an obvious case where it can mislead. That said, you appear to know the commenter better than I do (which is not at all), so I'll trust your judgement here.

pauamma · 2022-07-17T09:51:56Z

I am still working on it, please wait to merge.

I just flagged it as a draft so I remember not to do that. Let me know when it's ready.

lsalvadore · 2022-07-17T09:57:52Z

Thank you very much pauamma for your review. I did not know about drafts: I will use that next time.

- s/a user reported that he needed/a user reported needing/ [1] - Provide a bit more information about the LTO second example. Discussion is still in progress so the example cannot be completely clear, but we now give all the references necessary to follow the topic. Reported by: pauamma [1]

lsalvadore · 2022-07-20T00:11:26Z

I think this is ready for review now.

2022q2/gcc.adoc: Add warning about LTO

6349f4c

Warn users about the amount of ram and time needed to build GCC with LTO_BOOTSTRAP enabled. Reviewed by: gerald

pauamma reviewed Jul 14, 2022

View reviewed changes

2022q2/gcc.adoc: Give an idea of the ram needed

4b6b887

Suggested by: pauamma

lsalvadore requested review from GeraldPfeifer and removed request for GeraldPfeifer July 15, 2022 13:15

2022q2/gcc.adoc: Add another PR about LTO

17a9fcd

PR: 265254

lsalvadore requested a review from GeraldPfeifer July 16, 2022 22:51

pauamma reviewed Jul 17, 2022

View reviewed changes

pauamma marked this pull request as draft July 17, 2022 09:49

lsalvadore marked this pull request as ready for review July 20, 2022 00:11

pauamma approved these changes Jul 22, 2022

View reviewed changes

pauamma merged commit 282693c into freebsd:main Jul 22, 2022

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

2022q2/gcc.adoc: Add warning about LTO #489

2022q2/gcc.adoc: Add warning about LTO #489

lsalvadore commented Jul 14, 2022

pauamma Jul 14, 2022

lsalvadore Jul 14, 2022

pauamma Jul 15, 2022

lsalvadore Jul 15, 2022

pauamma Jul 17, 2022

lsalvadore commented Jul 16, 2022

pauamma Jul 17, 2022

pauamma Jul 17, 2022

lsalvadore Jul 17, 2022

pauamma Jul 17, 2022

pauamma commented Jul 17, 2022

lsalvadore commented Jul 17, 2022

lsalvadore commented Jul 20, 2022

2022q2/gcc.adoc: Add warning about LTO #489

2022q2/gcc.adoc: Add warning about LTO #489

Conversation

lsalvadore commented Jul 14, 2022

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

lsalvadore commented Jul 16, 2022

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

pauamma commented Jul 17, 2022

lsalvadore commented Jul 17, 2022

lsalvadore commented Jul 20, 2022