Buildworld and buildkernel with very slow compilation, recently

[Michael Grimm]

Dimitry Andric <dim at FreeBSD.org> wrote:
> 
> On 21 Jun 2020, at 14:36, Chris Nehren <cnehren at pobox.com> wrote:

>> On Sunday, June 21, 2020 8:11:15 AM EDT Michael Grimm wrote:
>>> Hi,
>>> 
>>> I am following FreeBSD 12.1-STABLE.
>>> 
>>> Clang has been upgraded to version 10.0.0 on May, 1st, and ever since that
>>> time, I do observe a dramatic increase in compilation times of building
>>> world, kernel and ports. I didn't benchmark the exact times, but
>>> compilation times are at least increased by a factor of 1.5. Nothing has
>>> changed of the last month besides upgrading 12.1-Stable every other week.
>>> 
>>> Has anyone else been bitten by this?
>> 
>> I don't have measurements to corroborate this, but here's a mailing list
>> thread where folks are talking about it (split across two URLs, the OP posted
>> in April and then there was a followup in May):
>> 
>> http://lists.llvm.org/pipermail/llvm-dev/2020-April/140938.html
>> https://lists.llvm.org/pipermail/llvm-dev/2020-May/141482.html
>> 
>> So there definitely seems to be *something* going on, and you are indeed not
>> crazy. :)
> 
> Indeed, there is some upstream discussion going on about this issue.
> There are some scenarios where people see non-negligible performance
> loss, but apparently not everybody suffers from it. If you build the
> whole ports collection, it is rather likely you may bump into it. I have
> personally not seen much performance difference in building world,
> kernel etc.
> 
> One of the upstream problems is that there is not really any
> authoritative performance regression log being built up, so it is hard
> to see where such regressions were introduced. Somebody then has to
> spend a lot of time tracking down each and every regression, and then
> attempt to untangle it from the dozens of commits made around the same
> time. :)
> 
> In any case, there is at least some attention on it now, so hopefully
> this will improve again. I don't think such fixes will be trivial
> though, so it is not likely they will land in 10.0.1.
> 
> -Dimitry

ok, so others see some performance loss as well.

In the meantime I activated META_MODE and hope, that will speed-up my weekly compilations.

Thanks to all who answered, and regards,
Michael