From: Zebediah Figura <zfigura@codeweavers.com>
To: "Gabriel Krisman Bertazi" <krisman@collabora.com>,
"André Almeida" <andrealmeid@collabora.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Darren Hart <dvhart@infradead.org>,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
kernel@collabora.com, pgriffais@valvesoftware.com,
joel@joelfernandes.org, malteskarupke@fastmail.fm,
linux-api@vger.kernel.org, fweimer@redhat.com,
libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org,
shuah@kernel.org, acme@kernel.org, corbet@lwn.net
Subject: Re: [RFC PATCH 03/13] futex2: Implement vectorized wait
Date: Mon, 15 Feb 2021 14:06:49 -0600 [thread overview]
Message-ID: <477b370d-575d-717f-ee49-9f1e30c737d5@codeweavers.com> (raw)
In-Reply-To: <87ft1xw123.fsf@collabora.com>
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On 2/15/21 2:03 PM, Gabriel Krisman Bertazi wrote:
> André Almeida <andrealmeid@collabora.com> writes:
>
>> Add support to wait on multiple futexes. This is the interface
>> implemented by this syscall:
>>
>> futex_waitv(struct futex_waitv *waiters, unsigned int nr_futexes,
>> unsigned int flags, struct timespec *timo)
>>
>> struct futex_waitv {
>> void *uaddr;
>> unsigned int val;
>> unsigned int flags;
>> };
>>
>> Given an array of struct futex_waitv, wait on each uaddr. The thread
>> wakes if a futex_wake() is performed at any uaddr. The syscall returns
>> immediately if any waiter has *uaddr != val. *timo is an optional
>> timeout value for the operation. The flags argument of the syscall
>> should be used solely for specifying the timeout as realtime, if needed.
>> Flags for shared futexes, sizes, etc. should be used on the individual
>> flags of each waiter.
>
> Given the previous proposal from Zebediah, one use case Wine has to
> support is the ability to wait on all (instead of any) of a list of
> futexes . I suppose that could be done by a new FLAG_WAITALL passed on
> the third argument of the syscall.
>
I don't think that such a feature would help Wine very much. It doesn't
fix any of the correctness problems with the futex-backed implementation
of NT primitives, and given the rarity of the wait-on-all operation I'm
inclined to believe it won't help performance either.
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next prev parent reply other threads:[~2021-02-15 20:07 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-15 15:23 [RFC PATCH 00/13] Add futex2 syscalls André Almeida
2021-02-15 15:23 ` [RFC PATCH 01/13] futex2: Implement wait and wake functions André Almeida
2021-02-15 19:59 ` Gabriel Krisman Bertazi
2021-02-18 13:29 ` André Almeida
2021-02-18 15:48 ` Gabriel Krisman Bertazi
2021-02-16 9:02 ` Peter Zijlstra
2021-02-18 20:09 ` André Almeida
2021-02-16 9:35 ` Peter Zijlstra
2021-02-16 9:56 ` Peter Zijlstra
2021-02-16 10:20 ` Sebastian Andrzej Siewior
2021-02-16 12:42 ` Peter Zijlstra
2021-02-16 22:12 ` Gabriel Krisman Bertazi
2021-02-15 15:23 ` [RFC PATCH 02/13] futex2: Add support for shared futexes André Almeida
2021-02-15 15:23 ` [RFC PATCH 03/13] futex2: Implement vectorized wait André Almeida
2021-02-15 20:03 ` Gabriel Krisman Bertazi
2021-02-15 20:06 ` Zebediah Figura [this message]
2021-02-15 20:08 ` Gabriel Krisman Bertazi
2021-02-15 15:23 ` [RFC PATCH 04/13] futex2: Implement requeue operation André Almeida
2021-02-15 15:23 ` [RFC PATCH 05/13] futex2: Add compatibility entry point for x86_x32 ABI André Almeida
2021-02-15 15:23 ` [RFC PATCH 06/13] docs: locking: futex2: Add documentation André Almeida
2021-02-16 18:34 ` Randy Dunlap
2021-02-18 19:12 ` André Almeida
2021-02-15 15:23 ` [RFC PATCH 07/13] selftests: futex2: Add wake/wait test André Almeida
2021-02-15 15:23 ` [RFC PATCH 08/13] selftests: futex2: Add timeout test André Almeida
2021-02-15 15:24 ` [RFC PATCH 09/13] selftests: futex2: Add wouldblock test André Almeida
2021-02-15 15:24 ` [RFC PATCH 10/13] selftests: futex2: Add waitv test André Almeida
2021-02-15 15:24 ` [RFC PATCH 11/13] selftests: futex2: Add requeue test André Almeida
2021-02-15 15:24 ` [RFC PATCH 12/13] perf bench: Add futex2 benchmark tests André Almeida
2021-02-15 15:24 ` [RFC PATCH 13/13] kernel: Enable waitpid() for futex2 André Almeida
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