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From:   Florian Weimer <fweimer@redhat.com>
To:     =?utf-8?Q?Andr=C3=A9?= Almeida <andrealmeid@collabora.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        "Pierre-Loup A. Griffais" <pgriffais@valvesoftware.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, kernel@collabora.com,
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        z.figura12@gmail.com, steven@valvesoftware.com,
        steven@liquorix.net, malteskarupke@web.de, carlos@redhat.com,
        adhemerval.zanella@linaro.org, libc-alpha@sourceware.org,
        linux-api@vger.kernel.org
Subject: Re: 'simple' futex interface [Was: [PATCH v3 1/4] futex: Implement mechanism to wait on any of several futexes]
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Date:   Thu, 05 Mar 2020 17:25:23 +0100
In-Reply-To: <52406c54-60b3-dcfe-65d8-4c425459e37b@collabora.com>
 (=?utf-8?Q?=22Andr=C3=A9?=
        Almeida"'s message of "Thu, 5 Mar 2020 13:14:17 -0300")
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* Andr=C3=A9 Almeida:

> Thanks everyone for the feedback around our mechanism. Are the
> performance benefits of implementing a syscall to wait on a single futex
> significant enough to maintain it instead of just using
> `sys_futex_waitv()` with `nr_waiters =3D 1`? If we join both cases in a
> single interface, we may even add a new member for NUMA hint in `struct
> futex_wait`.

Some seccomp user might want to verify the address, and that's easier if
it's in an argument.  But that's just a rather minor aspect.

Do you propose to drop the storage requirement for the NUMA hint
next to the futex completely?

Thanks,
Florian