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From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Paul McKenney <paulmck@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Arnd Bergmann <arnd@arndb.de>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>,
	linux-parisc@vger.kernel.org,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	linux-sh@vger.kernel.org, Jeff Dike <jdike@addtoit.com>,
	Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	linux-um@lists.infradead.org,
	Russell King <linux@armlinux.org.uk>,
	Marc Zyngier <maz@kernel.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [patch 10/19] preempt: Cleanup the macro maze a bit
Date: Tue, 17 Nov 2020 11:21:19 +0100	[thread overview]
Message-ID: <20201117102119.GE3121406@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <871rgtyz9g.fsf@nanos.tec.linutronix.de>

On Mon, Nov 16, 2020 at 06:42:19PM +0100, Thomas Gleixner wrote:
> On Mon, Nov 16 2020 at 13:17, Peter Zijlstra wrote:
> > On Fri, Nov 13, 2020 at 03:02:17PM +0100, Thomas Gleixner wrote:
> >
> >> -#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
> >> -				 | NMI_MASK))
> >> +#define irq_count()	(nmi_count() | hardirq_count() | softirq_count())
> >
> >
> >> +#define in_task()		(!(in_nmi() | in_hardirq() | in_serving_softirq()))
> >> -#define in_task()		(!(preempt_count() & \
> >> -				   (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
> >
> > How horrible is the code-gen? Because preempt_count() is
> > raw_cpu_read_4() and at least some old compilers will refuse to CSE it
> > (consider the this_cpu_read_stable mess).
> 
> I looked at gcc8 and 10 output and the compilers are smart enough to
> fold it for the !RT case. But yeah ...

If recent GCC is smart enough I suppose it doesn't matter, thanks!

WARNING: multiple messages have this Message-ID
From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <maz@kernel.org>, Rich Felker <dalias@libc.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Paul McKenney <paulmck@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	linux-sh@vger.kernel.org, Richard Weinberger <richard@nod.at>,
	Frederic Weisbecker <frederic@kernel.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Jeff Dike <jdike@addtoit.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	linux-parisc@vger.kernel.org, Helge Deller <deller@gmx.de>,
	Russell King <linux@armlinux.org.uk>,
	linux-um@lists.infradead.org, Will Deacon <will@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>
Subject: Re: [patch 10/19] preempt: Cleanup the macro maze a bit
Date: Tue, 17 Nov 2020 11:21:19 +0100	[thread overview]
Message-ID: <20201117102119.GE3121406@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <871rgtyz9g.fsf@nanos.tec.linutronix.de>

On Mon, Nov 16, 2020 at 06:42:19PM +0100, Thomas Gleixner wrote:
> On Mon, Nov 16 2020 at 13:17, Peter Zijlstra wrote:
> > On Fri, Nov 13, 2020 at 03:02:17PM +0100, Thomas Gleixner wrote:
> >
> >> -#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
> >> -				 | NMI_MASK))
> >> +#define irq_count()	(nmi_count() | hardirq_count() | softirq_count())
> >
> >
> >> +#define in_task()		(!(in_nmi() | in_hardirq() | in_serving_softirq()))
> >> -#define in_task()		(!(preempt_count() & \
> >> -				   (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
> >
> > How horrible is the code-gen? Because preempt_count() is
> > raw_cpu_read_4() and at least some old compilers will refuse to CSE it
> > (consider the this_cpu_read_stable mess).
> 
> I looked at gcc8 and 10 output and the compilers are smart enough to
> fold it for the !RT case. But yeah ...

If recent GCC is smart enough I suppose it doesn't matter, thanks!

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  reply	other threads:[~2020-11-17 10:22 UTC|newest]

Thread overview: 115+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-13 14:02 [patch 00/19] softirq: Cleanups and RT awareness Thomas Gleixner
2020-11-13 14:02 ` Thomas Gleixner
2020-11-13 14:02 ` Thomas Gleixner
2020-11-13 14:02 ` [patch 01/19] parisc: Remove bogus __IRQ_STAT macro Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 02/19] sh: Get rid of nmi_count() Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2021-01-01 14:27   ` [patch 02/19] " John Paul Adrian Glaubitz
2021-01-01 14:27     ` John Paul Adrian Glaubitz
2020-11-13 14:02 ` [patch 03/19] irqstat: Get rid of nmi_count() and __IRQ_STAT() Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 04/19] um/irqstat: Get rid of the duplicated declarations Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 05/19] ARM: irqstat: Get rid of duplicated declaration Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-16 18:19   ` Valentin Schneider
2020-11-16 18:19     ` Valentin Schneider
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 06/19] arm64: " Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-16 10:01   ` Will Deacon
2020-11-16 10:01     ` Will Deacon
2020-11-16 10:01     ` Will Deacon
2020-11-16 10:51   ` Marc Zyngier
2020-11-16 10:51     ` Marc Zyngier
2020-11-16 10:51     ` Marc Zyngier
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 07/19] asm-generic/irqstat: Add optional __nmi_count member Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 08/19] sh: irqstat: Use the generic irq_cpustat_t Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 09/19] irqstat: Move declaration into asm-generic/hardirq.h Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 10/19] preempt: Cleanup the macro maze a bit Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-16 12:17   ` Peter Zijlstra
2020-11-16 12:17     ` Peter Zijlstra
2020-11-16 12:17     ` Peter Zijlstra
2020-11-16 17:42     ` Thomas Gleixner
2020-11-16 17:42       ` Thomas Gleixner
2020-11-16 17:42       ` Thomas Gleixner
2020-11-17 10:21       ` Peter Zijlstra [this message]
2020-11-17 10:21         ` Peter Zijlstra
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 11/19] softirq: Move related code into one section Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-19 12:20   ` Frederic Weisbecker
2020-11-19 12:20     ` Frederic Weisbecker
2020-11-23 22:51   ` [tip: irq/core] " tip-bot2 for Thomas Gleixner
2020-11-13 14:02 ` [patch 12/19] softirq: Add RT specific softirq accounting Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-19 12:18   ` Frederic Weisbecker
2020-11-19 12:18     ` Frederic Weisbecker
2020-11-19 18:34     ` Thomas Gleixner
2020-11-19 18:34       ` Thomas Gleixner
2020-11-19 22:52       ` Frederic Weisbecker
2020-11-19 22:52         ` Frederic Weisbecker
2020-11-13 14:02 ` [patch 13/19] softirq: Move various protections into inline helpers Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02 ` [patch 14/19] softirq: Make softirq control and processing RT aware Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-20  0:26   ` Frederic Weisbecker
2020-11-20  0:26     ` Frederic Weisbecker
2020-11-20 13:27     ` Thomas Gleixner
2020-11-20 13:27       ` Thomas Gleixner
2020-11-23 13:44   ` Frederic Weisbecker
2020-11-23 13:44     ` Frederic Weisbecker
2020-11-23 19:27     ` Thomas Gleixner
2020-11-23 19:27       ` Thomas Gleixner
2020-11-23 19:56       ` Frederic Weisbecker
2020-11-23 19:56         ` Frederic Weisbecker
2020-11-23 23:58       ` Frederic Weisbecker
2020-11-23 23:58         ` Frederic Weisbecker
2020-11-24  0:06         ` Thomas Gleixner
2020-11-24  0:06           ` Thomas Gleixner
2020-11-24  0:13           ` Frederic Weisbecker
2020-11-24  0:13             ` Frederic Weisbecker
2020-11-24  0:22             ` Thomas Gleixner
2020-11-24  0:22               ` Thomas Gleixner
2020-11-13 14:02 ` [patch 15/19] tick/sched: Prevent false positive softirq pending warnings on RT Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02 ` [patch 16/19] rcu: Prevent false positive softirq warning " Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02 ` [patch 17/19] softirq: Replace barrier() with cpu_relax() in tasklet_unlock_wait() Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02 ` [patch 18/19] tasklets: Use static inlines for stub implementations Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02 ` [patch 19/19] tasklets: Prevent kill/unlock_wait deadlock on RT Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner
2020-11-13 14:02   ` Thomas Gleixner

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