linux-kernel - Re: [PATCH v3 2/6] futex2: Implement vectorized wait

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Date:   Thu, 16 Sep 2021 12:36:21 -0400
From:   Gabriel Krisman Bertazi <krisman@...labora.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        André Almeida <andrealmeid@...labora.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Darren Hart <dvhart@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Collabora kernel ML <kernel@...labora.com>,
        Linux API <linux-api@...r.kernel.org>,
        GNU C Library <libc-alpha@...rceware.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Davidlohr Bueso <dave@...olabs.net>
Subject: Re: [PATCH v3 2/6] futex2: Implement vectorized wait

Arnd Bergmann <arnd@...db.de> writes:

> On Thu, Sep 16, 2021 at 1:22 PM Peter Zijlstra <peterz@...radead.org> wrote:
>>
>> On Thu, Sep 16, 2021 at 12:10:25AM -0400, Gabriel Krisman Bertazi wrote:
>>
>> > I find this weird.  I'm not even juts talking about compat, but even on
>> > native 32-bit. But also, 32 applications on 64, which is a big use
>> > case for games.
>>
>> Seriously, people still make 32bit applications today? And for legacy
>> games, I would think the speed increase of modern CPUs would far offset
>> this little inefficiency.
>
> There are 32-bit Windows games apparently, because it's easier to build it
> that way than having both 32-bit and 64-bit versions.

Yes, many modern, recently released, tiple-A Windows games running over
Proton/Wine are published only in 32-bit.  We also keep a 32-bit Proton
for that reason.

> There may be native 32-bit games built for Linux from the same sources when
> that is not written portably, not sure if that's a thing.
>
> One important reason to use compat mode is for cost savings when you can
> ship an embedded system with slightly less RAM by running 32-bit user space
> on it. We even still see people running 32-bit kernels on Arm boxes that have
> entry-level 64-bit chips, though I hope that those will migrate the
> kernel to arm64
> even when they ship 32-bit user space.
>
> Similar logic applies to cloud instances or containers. Running a 32-bit
> Alpine Linux in a container means you can often go to a lower memory
> instance on the host compared to a full 64-bit distro.
>
>         Arnd

-- 
Gabriel Krisman Bertazi