From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: "Ahmed S. Darwish" <a.darwish@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
the arch/x86 maintainers <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
bigeasy@linutronix.de, "David S. Miller" <davem@davemloft.net>,
sparclinux@vger.kernel.org, Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, heiko.carstens@de.ibm.com,
linux-s390@vger.kernel.org, linux@armlinux.org.uk,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} to per-cpu variables
Date: Wed, 24 Jun 2020 14:31:47 +0200 [thread overview]
Message-ID: <20200624123147.GH4781@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CANpmjNMj8FZuBrZsH62V3bZEhFvT2zXwLusVOLwNuH_-kLhp2g@mail.gmail.com>
On Wed, Jun 24, 2020 at 12:17:56PM +0200, Marco Elver wrote:
> On Wed, 24 Jun 2020 at 11:01, Peter Zijlstra <peterz@infradead.org> wrote:
> > And I figured a quick way to get rid of that would be something like the
> > below, seeing how volatile gets auto annotated... but that doesn't seem
> > to actually work.
> >
> > What am I missing?
>
> There's one more in include/linux/rcupdate.h. I suggested this at some point:
>
> https://lore.kernel.org/lkml/20200220213317.GA35033@google.com/
>
> To avoid volatiles as I don't think they are needed here.
Urgghh.. local_t is very expensive for this. The current code is
actually fine, even on load-store architectures. Using local_t will only
result in it being more expensive for no gain.
I'll go put data_race() around it.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: "Ahmed S. Darwish" <a.darwish@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
the arch/x86 maintainers <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
bigeasy@linutronix.de, "David S. Miller" <davem@davemloft.net>,
sparclinux@vger.kernel.org, Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, heiko.carstens@de.ibm.com,
linux-s390@vger.kernel.org, linux@armlinux.org.uk,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} to per-cpu variables
Date: Wed, 24 Jun 2020 12:31:47 +0000 [thread overview]
Message-ID: <20200624123147.GH4781@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CANpmjNMj8FZuBrZsH62V3bZEhFvT2zXwLusVOLwNuH_-kLhp2g@mail.gmail.com>
On Wed, Jun 24, 2020 at 12:17:56PM +0200, Marco Elver wrote:
> On Wed, 24 Jun 2020 at 11:01, Peter Zijlstra <peterz@infradead.org> wrote:
> > And I figured a quick way to get rid of that would be something like the
> > below, seeing how volatile gets auto annotated... but that doesn't seem
> > to actually work.
> >
> > What am I missing?
>
> There's one more in include/linux/rcupdate.h. I suggested this at some point:
>
> https://lore.kernel.org/lkml/20200220213317.GA35033@google.com/
>
> To avoid volatiles as I don't think they are needed here.
Urgghh.. local_t is very expensive for this. The current code is
actually fine, even on load-store architectures. Using local_t will only
result in it being more expensive for no gain.
I'll go put data_race() around it.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
"Paul E. McKenney" <paulmck@kernel.org>,
bigeasy@linutronix.de, the arch/x86 maintainers <x86@kernel.org>,
heiko.carstens@de.ibm.com, LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
"David S. Miller" <davem@davemloft.net>,
"Ahmed S. Darwish" <a.darwish@linutronix.de>,
sparclinux@vger.kernel.org, linux@armlinux.org.uk,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} to per-cpu variables
Date: Wed, 24 Jun 2020 14:31:47 +0200 [thread overview]
Message-ID: <20200624123147.GH4781@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CANpmjNMj8FZuBrZsH62V3bZEhFvT2zXwLusVOLwNuH_-kLhp2g@mail.gmail.com>
On Wed, Jun 24, 2020 at 12:17:56PM +0200, Marco Elver wrote:
> On Wed, 24 Jun 2020 at 11:01, Peter Zijlstra <peterz@infradead.org> wrote:
> > And I figured a quick way to get rid of that would be something like the
> > below, seeing how volatile gets auto annotated... but that doesn't seem
> > to actually work.
> >
> > What am I missing?
>
> There's one more in include/linux/rcupdate.h. I suggested this at some point:
>
> https://lore.kernel.org/lkml/20200220213317.GA35033@google.com/
>
> To avoid volatiles as I don't think they are needed here.
Urgghh.. local_t is very expensive for this. The current code is
actually fine, even on load-store architectures. Using local_t will only
result in it being more expensive for no gain.
I'll go put data_race() around it.
next prev parent reply other threads:[~2020-06-24 12:32 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 8:36 [PATCH v4 0/8] lockdep: Change IRQ state tracking to use per-cpu variables Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 1/8] lockdep: Prepare for NMI IRQ state tracking Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 2/8] x86/entry: Fix NMI vs " Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 3/8] sparc64: Fix asm/percpu.h build error Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 21:35 ` David Miller
2020-06-23 21:35 ` David Miller
2020-06-23 21:35 ` David Miller
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 4/8] powerpc64: Break asm/percpu.h vs spinlock_types.h dependency Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 5/8] s390: Break cyclic percpu include Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 6/8] arm: " Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 8:36 ` Peter Zijlstra
2020-06-23 9:02 ` Will Deacon
2020-06-23 9:02 ` Will Deacon
2020-06-23 9:02 ` Will Deacon
2020-06-24 17:53 ` Peter Zijlstra
2020-06-24 17:53 ` Peter Zijlstra
2020-06-24 17:53 ` Peter Zijlstra
2020-06-25 7:31 ` Will Deacon
2020-06-25 7:31 ` Will Deacon
2020-06-25 7:31 ` Will Deacon
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} to per-cpu variables Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 7/8] lockdep: Change hardirq{s_enabled, _context} " Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} " Peter Zijlstra
2020-06-23 15:00 ` Ahmed S. Darwish
2020-06-23 15:00 ` Ahmed S. Darwish
2020-06-23 15:00 ` Ahmed S. Darwish
2020-06-23 15:24 ` Peter Zijlstra
2020-06-23 15:24 ` Peter Zijlstra
2020-06-23 15:24 ` Peter Zijlstra
2020-06-23 16:13 ` Ahmed S. Darwish
2020-06-23 16:13 ` Ahmed S. Darwish
2020-06-23 16:13 ` Ahmed S. Darwish
2020-06-23 16:37 ` Peter Zijlstra
2020-06-23 16:37 ` Peter Zijlstra
2020-06-23 16:37 ` Peter Zijlstra
2020-06-23 17:59 ` Marco Elver
2020-06-23 17:59 ` Marco Elver
2020-06-23 17:59 ` Marco Elver
2020-06-23 18:12 ` Peter Zijlstra
2020-06-23 18:12 ` Peter Zijlstra
2020-06-23 18:12 ` Peter Zijlstra
2020-06-23 18:39 ` Marco Elver
2020-06-23 18:39 ` Marco Elver
2020-06-23 18:39 ` Marco Elver
2020-06-23 19:13 ` Marco Elver
2020-06-23 19:13 ` Marco Elver
2020-06-23 19:13 ` Marco Elver
2020-06-23 19:41 ` Peter Zijlstra
2020-06-23 19:41 ` Peter Zijlstra
2020-06-23 19:41 ` Peter Zijlstra
2020-06-23 20:08 ` Peter Zijlstra
2020-06-23 20:08 ` Peter Zijlstra
2020-06-23 20:08 ` Peter Zijlstra
2020-06-23 20:24 ` Peter Zijlstra
2020-06-23 20:24 ` Peter Zijlstra
2020-06-23 20:24 ` Peter Zijlstra
2020-06-23 20:33 ` Peter Zijlstra
2020-06-23 20:33 ` Peter Zijlstra
2020-06-23 20:33 ` Peter Zijlstra
2020-06-24 9:00 ` Peter Zijlstra
2020-06-24 9:00 ` Peter Zijlstra
2020-06-24 9:00 ` Peter Zijlstra
2020-06-24 10:17 ` Marco Elver
2020-06-24 10:17 ` Marco Elver
2020-06-24 10:17 ` Marco Elver
2020-06-24 12:31 ` Peter Zijlstra [this message]
2020-06-24 12:31 ` Peter Zijlstra
2020-06-24 12:31 ` Peter Zijlstra
2020-06-24 11:32 ` Marco Elver
2020-06-24 11:32 ` Marco Elver
2020-06-24 11:32 ` Marco Elver
2020-06-24 15:18 ` Peter Zijlstra
2020-06-24 15:18 ` Peter Zijlstra
2020-06-24 15:18 ` Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] kcsan: Make KCSAN compatible with new IRQ state tracking tip-bot2 for Marco Elver
2020-06-30 5:59 ` [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} to per-cpu variables Ahmed S. Darwish
2020-06-30 5:59 ` Ahmed S. Darwish
2020-06-30 5:59 ` Ahmed S. Darwish
2020-06-30 9:40 ` Peter Zijlstra
2020-06-30 9:40 ` Peter Zijlstra
2020-06-30 9:40 ` Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 8/8] lockdep: Remove lockdep_hardirq{s_enabled,_context}() argument Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 8/8] lockdep: Remove lockdep_hardirq{s_enabled, _context}() argument Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 8/8] lockdep: Remove lockdep_hardirq{s_enabled,_context}() argument Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
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