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From: Paul Eggert <eggert@cs.ucla.edu>
To: Peter Zijlstra <peterz@infradead.org>,
	andrealmeid@collabora.com, tglx@linutronix.de, 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: Wed, 15 Sep 2021 10:34:17 -0700	[thread overview]
Message-ID: <bdeb5453-e019-7c5b-1bf0-7a225401d358@cs.ucla.edu> (raw)
In-Reply-To: <YUITUXbnzAK98DEl@hirez.programming.kicks-ass.net>

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.

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. 
This could use __int128 on platforms that have it, a two-integer struct 
otherwise.

I'm not sure this is a hill I'd want to die on. That being said, it 
would be cool to keep up with the people in the building near mine who 
are researching attosecond imaging (tricky because the uncertainty 
principle means attosecond laser pulses must have very broad spectra). 
And extending struct timespec on the low end is clearly the way to go, 
since its high end already goes back well before the Big Bang.

I hope you don't mind my going off the deep end a bit here. Still, the 
point is that if we're going to improve on struct timespec then it 
really should be an improvement.

  reply	other threads:[~2021-09-15 17:43 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 [this message]
2021-09-16 14:49       ` Thomas Gleixner
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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