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From: Alexandre Oliva <>
To: Jonathan Wakely <>
Cc: gcc Patches <>,
	"libstdc++" <>
Subject: Re: [PATCH] libstdc++: testsuite: call sched_yield for nonpreemptive targets
Date: Tue, 21 Jun 2022 21:20:43 -0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <> (Jonathan Wakely's message of "Tue, 21 Jun 2022 08:38:47 +0100")

On Jun 21, 2022, Jonathan Wakely <> wrote:

> On Tue, 21 Jun 2022 at 06:54, Alexandre Oliva via Libstdc++
> <> wrote:
>> As in the gcc testsuite, systems without preemptive multi-threading
>> require sched_yield calls to be placed at points in which a context
>> switch might be needed to enable the test to complete.

> I'll try to remember that, but will probably forget. Is this really
> the only affected test?

Yeah, the only one in libstdc++-v3/testsuite, as of gcc-11, which is
what I've focused on for this project; I haven't gone through all fails
on master to make sure they're unrelated.  (This is holding up some
filesystem-related patches, whose tests are failing for reasons not
present in gcc-11, and some of the forward-ports needed significant

libstdc++ has plenty of threading tests, but they involve sleeping or
otherwise blocking, which offers a context switch opportunity even on
non-preemptive multithreading systems.  It's busy waits that require a
sched_yield.  The gcc testsuite has a handful of those; covered by a
separate patch also posted last night.

Alexandre Oliva, happy hacker      
   Free Software Activist                       GNU Toolchain Engineer
Disinformation flourishes because many people care deeply about injustice
but very few check the facts.  Ask me about <>

      reply	other threads:[~2022-06-22  0:20 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-21  5:52 Alexandre Oliva
2022-06-21  7:38 ` Jonathan Wakely
2022-06-22  0:20   ` Alexandre Oliva [this message]

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