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From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: umgwanakikbuti@gmail.com, mingo@elte.hu, ktkhai@parallels.com,
	rostedt@goodmis.org, tglx@linutronix.de, juri.lelli@gmail.com,
	pang.xunlei@linaro.org, oleg@redhat.com,
	wanpeng.li@linux.intel.com, linux-kernel@vger.kernel.org,
	Al Viro <viro@ZenIV.linux.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 11/18] seqcount: Introduce raw_write_seqcount_barrier()
Date: Wed, 17 Jun 2015 18:58:02 +0200	[thread overview]
Message-ID: <20150617165802.GF19282@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20150617154245.GB3913@linux.vnet.ibm.com>

On Wed, Jun 17, 2015 at 08:42:45AM -0700, Paul E. McKenney wrote:
> > I would very much prefer a compiler switch that instructs the compiler
> > to not do bloody stupid things like this instead of marking every other
> > load/store in the kernel with volatile.
> 
> I would of course be good with such a compiler switch, though my earlier
> attempts to negotiate one were unsuccessful.  But I don't believe that we
> discussed a switch to specifically prohibit only use of to-be-stored-into
> variables as temporary scratch space.  The trick is finding restrictions
> that are useful, but that don't imply -O0.

I would request on that disables all the 'stores from thin air'
'optimizations'. IOW assume everything is shared memory and concurrent
unless you can prove its not so. For example a local stack variable that
does not escape scope.

  reply	other threads:[~2015-06-17 16:58 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-11 12:46 [PATCH 00/18] sched: balance callbacks v4 Peter Zijlstra
2015-06-11 12:46 ` [PATCH 01/18] sched: Replace post_schedule with a balance callback list Peter Zijlstra
2015-06-11 15:32   ` Kirill Tkhai
2015-06-18 23:00   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 02/18] sched: Use replace normalize_task() with __sched_setscheduler() Peter Zijlstra
2015-06-18 23:00   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 03/18] sched: Allow balance callbacks for check_class_changed() Peter Zijlstra
2015-06-18 23:01   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 04/18] sched,rt: Remove return value from pull_rt_task() Peter Zijlstra
2015-06-18 23:01   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 05/18] sched,rt: Convert switched_{from,to}_rt() / prio_changed_rt() to balance callbacks Peter Zijlstra
2015-06-18 23:01   ` [tip:sched/hrtimers] sched, rt: Convert switched_{from, to}_rt() " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 06/18] sched,dl: Remove return value from pull_dl_task() Peter Zijlstra
2015-06-18 23:02   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 07/18] sched,dl: Convert switched_{from,to}_dl() / prio_changed_dl() to balance callbacks Peter Zijlstra
2015-06-18 23:02   ` [tip:sched/hrtimers] sched, dl: Convert switched_{from, to}_dl() " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 08/18] hrtimer: Remove HRTIMER_STATE_MIGRATE Peter Zijlstra
2015-06-18 22:18   ` [tip:timers/core] " tip-bot for Oleg Nesterov
2015-06-11 12:46 ` [PATCH 09/18] hrtimer: Fix hrtimer_is_queued() hole Peter Zijlstra
2015-06-18 22:18   ` [tip:timers/core] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 10/18] seqcount: Rename write_seqcount_barrier() Peter Zijlstra
2015-06-18 22:19   ` [tip:timers/core] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 11/18] seqcount: Introduce raw_write_seqcount_barrier() Peter Zijlstra
2015-06-11 15:33   ` Paul E. McKenney
2015-06-11 21:45     ` Paul E. McKenney
2015-06-12  7:08       ` Peter Zijlstra
2015-06-12 18:59       ` Oleg Nesterov
2015-06-17 12:29       ` Peter Zijlstra
2015-06-17 14:57         ` Paul E. McKenney
2015-06-17 15:11           ` Peter Zijlstra
2015-06-17 15:42             ` Paul E. McKenney
2015-06-17 16:58               ` Peter Zijlstra [this message]
2015-06-17 15:49           ` Peter Zijlstra
2015-06-17 16:37             ` Paul E. McKenney
2015-06-17 17:11               ` Peter Zijlstra
2015-06-17 18:02                 ` Paul E. McKenney
2015-06-18  9:15                   ` Peter Zijlstra
2015-06-18  9:40                     ` Ingo Molnar
2015-06-18 10:40                       ` Peter Zijlstra
2015-06-18 16:54                         ` Paul E. McKenney
2015-06-18 17:10                           ` Steven Rostedt
2015-06-18 17:51                             ` Paul E. McKenney
2015-06-18 22:19         ` [tip:timers/core] seqcount: Introduce raw_write_seqcount_barrier( ) tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 12/18] hrtimer: Allow hrtimer::function() to free the timer Peter Zijlstra
2015-06-18 22:19   ` [tip:timers/core] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 13/18] sched,dl: Fix sched class hopping CBS hole Peter Zijlstra
2015-06-18 23:02   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 14/18] sched: Move code around Peter Zijlstra
2015-06-18 23:02   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 15/18] sched: Streamline the task migration locking a little Peter Zijlstra
2015-06-18 23:03   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 16/18] lockdep: Simplify lock_release() Peter Zijlstra
2015-06-18 23:03   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 17/18] lockdep: Implement lock pinning Peter Zijlstra
2015-06-18 23:03   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 18/18] sched,lockdep: Employ " Peter Zijlstra
2015-06-18 23:04   ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-12-29  5:41 ` [PATCH 00/18] sched: balance callbacks v4 Byungchul Park

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