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From: Thomas Gleixner <tglx@linutronix.de>
To: Paul Eggert <eggert@cs.ucla.edu>,
	Peter Zijlstra <peterz@infradead.org>,
	andrealmeid@collabora.com, mingo@redhat.com,
	dvhart@infradead.org, rostedt@goodmis.org, bigeasy@linutronix.de
Cc: dave@stgolabs.net, libc-alpha@sourceware.org,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
	mtk.manpages@gmail.com, kernel@collabora.com,
	krisman@collabora.com
Subject: Re: [PATCH 16/20] futex: Implement sys_futex_waitv()
Date: Thu, 16 Sep 2021 16:49:21 +0200	[thread overview]
Message-ID: <87tuika83y.ffs@tglx> (raw)
In-Reply-To: <bdeb5453-e019-7c5b-1bf0-7a225401d358@cs.ucla.edu>

On Wed, Sep 15 2021 at 10:34, Paul Eggert wrote:

> On 9/15/21 8:37 AM, Peter Zijlstra wrote:
>> I utterly detest timespec.. it makes no sense what so ever.
>> 
>> Can't we just, for new syscalls, simply use a s64 nsec argument and call
>> it a day?
>
> This would stop working in the year 2262. Not a good idea.

Make it u64 and it stops in 2552, i.e. 584 years from now which is
plenty. Lot's of the kernel internal timekeeping will stop working at
that point, so that interface is the least of my worries. And TBH, my
worries about the Y2552 problem are extremly close to zero.

> Any improvements on struct timespec should be a strict superset, not a 
> subset. For example, you could advocate a signed 128-bit argument 
> counting in units of attoseconds (10⁻¹⁸ s), the highest power-of-1000 
> resolution that does not lose info when converting from struct
> timespec.

Which requires a 128bit division on every syscall for no value at all.

Thanks,

        tglx

  reply	other threads:[~2021-09-16 14:49 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-15 14:07 [PATCH 00/20] futex: splitup and waitv syscall Peter Zijlstra
2021-09-15 14:07 ` [PATCH 01/20] futex: Move to kernel/futex/ Peter Zijlstra
2021-09-15 14:07 ` [PATCH 02/20] futex: Split out syscalls Peter Zijlstra
2021-09-15 14:07 ` [PATCH 03/20] futex: Rename {,__}{,un}queue_me() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 04/20] futex: Rename futex_wait_queue_me() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 05/20] futex: Rename: queue_{,un}lock() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 06/20] futex: Rename __unqueue_futex() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 07/20] futex: Rename hash_futex() Peter Zijlstra
2021-09-15 15:17   ` André Almeida
2021-09-15 15:22     ` Peter Zijlstra
2021-09-15 14:07 ` [PATCH 08/20] futex: Rename: {get,cmpxchg}_futex_value_locked() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 09/20] futex: Split out PI futex Peter Zijlstra
2021-09-15 14:07 ` [PATCH 10/20] futex: Rename: hb_waiter_{inc,dec,pending}() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 11/20] futex: Rename: match_futex() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 12/20] futex: Rename mark_wake_futex() Peter Zijlstra
2021-09-15 14:07 ` [PATCH 13/20] futex: Split out requeue Peter Zijlstra
2021-09-15 14:07 ` [PATCH 14/20] futex: Split out wait/wake Peter Zijlstra
2021-09-15 14:07 ` [PATCH 15/20] futex: Simplify double_lock_hb() Peter Zijlstra
2021-09-15 15:13 ` [PATCH 00/20] futex: splitup and waitv syscall André Almeida
     [not found] ` <20210915141525.621568509@infradead.org>
2021-09-15 15:20   ` [PATCH 16/20] futex: Implement sys_futex_waitv() André Almeida
2021-09-15 15:37   ` Peter Zijlstra
2021-09-15 17:34     ` Paul Eggert
2021-09-16 14:49       ` Thomas Gleixner [this message]
2021-09-16 18:54         ` André Almeida
2021-09-15 18:47     ` Arnd Bergmann
2021-09-15 16:29   ` André Almeida
2021-09-15 18:24 ` [PATCH 00/20] futex: splitup and waitv syscall André Almeida

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