[PATCH] libstdc++: Increase timeout for 23_containers/mdspan/submdspan tests [PR124290]

[Rainer Orth]

Hi Jonathan,

> On Thu, 12 Mar 2026 at 09:05, Rainer Orth <ro@cebitec.uni-bielefeld.de> wrote:
>>
>> The 23_containers/mdspan/submdspan/selections tests often time out on
>> Solaris/SPARC:
>>
>> WARNING: 23_containers/mdspan/submdspan/selections/left_padded.cc  -std=gnu++26 (test for excess errors) program timed out.
>> FAIL: 23_containers/mdspan/submdspan/selections/left_padded.cc  -std=gnu++26 (test for excess errors)
>>
>> Even on an unloaded system, compilation takes ca. 4 minutes, close to
>> the default DejaGnu timeout of 5 minutes.  Setting/increasing the
>> timeout factor to 2 was not enough, so this patch raises it to 4 for all
>> 5 tests.
>
> It takes less than 30 seconds on my i7-9850H 2.60GHz x86_64 laptop, I
> wonder what the reason for the difference is.

true: a 32-bit-default gcc on Solaris/x86 (Xeon Gold 6132, 2.60GHz)
takes 52.12s, 32-bit-default on Linux/x86_64 (EPYC 7763, 2.45GHz) is
36.981s, even 64-bit-default on Linux/sparc64 (SPARC-M7, 4.27GHz) is
1m42.950s, while Solaris/sparcv9 (SPARC-M8, 5.07GHz) is 4:22.88.

I haven't run a Solaris/sparcv9 build on the M7 recently, so I cannot
directly compare that to Linux/sparc64.

-ftime-report is useless in 32-bit compilers, unfortunately:

Time variable                                  wall           GGC
 phase setup                        :   0.01 (  0%)  1060k (  0%)
 phase parsing                      :18446744072.97 (100%)  1032M ( 72%)
[...]
 TOTAL                              :18446744069.90         1430M

For Solaris/sparcv9 the top consumers are

 callgraph ipa passes               :  15.02 (  2%)   0.62 ( 14%)  15.77 (  2%)   26149 kB ( 10%)
 alias stmt walking                 :  14.30 (  2%)   0.23 (  5%)  14.43 (  2%)     182 kB (  0%)
 scheduling                         :  30.13 (  3%)   0.17 (  4%)  30.35 (  3%)    2370 kB (  1%)
 var-tracking dataflow              : 424.42 ( 45%)   0.25 (  6%) 424.65 ( 45%)    1422 kB (  1%)
 var-tracking emit                  : 360.20 ( 39%)   0.21 (  5%) 360.54 ( 38%)    2286 kB (  1%)

Everything else is 1% or less.

	Rainer

-- 
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Rainer Orth, Center for Biotechnology, Bielefeld University