On 7/31/19 9:34 AM, Jakub Jelinek wrote:
> On Wed, Jul 31, 2019 at 09:20:40AM +0200, Martin Liška wrote:
>> One possible solution will be to adjust lto.exp:
>>
>> set LTO_OPTIONS [list \
>> {-O0 -flto -flto-partition=none -fuse-linker-plugin} \
>> {-O2 -flto -flto-partition=none -fuse-linker-plugin
>> -fno-fat-lto-objects } \
>> {-O0 -flto -flto-partition=1to1 -fno-use-linker-plugin } \
>> {-O2 -flto -flto-partition=1to1 -fno-use-linker-plugin } \
>>
>> and replace all -flto with -flto=1. But still, many individual tests set
>> -flto by themselves.
>> Another solution would be to disable the auto-detection with an environment
>> variable:
>>
>> diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
>> index 353187c6043..bb6fb2b53ff 100644
>> --- a/gcc/lto-wrapper.c
>> +++ b/gcc/lto-wrapper.c
>> @@ -1423,7 +1423,7 @@ run_gcc (unsigned argc, char *argv[])
>> auto_parallel = 0;
>> parallel = 0;
>> }
>> - else if (!jobserver && parallel)
>> + else if (!jobserver && parallel && !getenv ("LTO_NO_AUTO_PARALLEL"))
>> {
>> /* If there's no explicit usage of jobserver and
>> parallel is enabled, then automatically detect
>> diff --git a/gcc/testsuite/lib/lto.exp b/gcc/testsuite/lib/lto.exp
>> index 25c934731df..e303894e0b0 100644
>> --- a/gcc/testsuite/lib/lto.exp
>> +++ b/gcc/testsuite/lib/lto.exp
>> @@ -209,6 +209,8 @@ proc lto_init { args } {
>> ]
>> }
>> }
>> +
>> + setenv LTO_NO_AUTO_PARALLEL 1
>> }
>>
>> #
>>
>> Can you Jakub test the patch or the s/-flto/-flto=1 solutions please?
>
> Neither will work very well, we have thousands of -flto tests outside of
> lto.exp, e.g. dg-torture.exp (or libgomp and others) cycle through various
> options including -flto etc.
>
> Some env var would be useful I guess, though shouldn't it have GCC in the
> name?
Works for me.
> I mean, if we run into these fork-bomb problems in gcc, won't other
> projects run into those as well?
Right now, we build whole openSUSE distribution with -flto=N (N based on # of
threads)
and we haven't seen issues related to fork-bomb.
>
> Why doesn't the jobserver work in the tests? Is that because of missing +
> somewhere in the Makefiles or is something unsetting MFLAGS or MAKEFLAGS
> env vars?
Is Dejagnu using make internally to invoke individual tests?
>
> Though, as I said on IRC, I think we might run out of filedescriptors when
> using jobserver too, say if on 64 thread machine one does make -j64 -k check
> and each test simultaneously tries to create 64 partitions, that would be
> 4096 connections to the jobserver, right?
>
> Jakub
>
