From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <namit@vmware.com>, Ingo Molnar <mingo@kernel.org>,
Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Lutomirski <luto@kernel.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH 1/5] x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}()
Date: Fri, 8 Mar 2019 14:35:10 +0100 [thread overview]
Message-ID: <20190308133510.GX32494@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHk-=wgfx6rUXpH16A9OAyEEh9nf18pk9mL7Wkz5b6eDc9dPpA@mail.gmail.com>
On Wed, Feb 27, 2019 at 11:41:31AM -0800, Linus Torvalds wrote:
> On Wed, Feb 27, 2019 at 9:57 AM Nadav Amit <namit@vmware.com> wrote:
> >
> > I’ll have a look at some specific function assembly, but overall, the “+m”
> > approach might prevent even more code optimizations than the “volatile” one.
>
> Ok, that being the case, let's forget that patch.
>
> I still wonder about the added volatiles to the xadd/cmpxchg cases,
> which already had the "memory" clobber which should make the volatile
> immaterial..
That was mostly me being OCD style consistent; but also notice that the
atomic ops also often have volatile even though they have a memory
clobber.
next prev parent reply other threads:[~2019-03-08 13:35 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-27 10:12 [PATCH 0/5] x86/percpu semantics and fixes Peter Zijlstra
2019-02-27 10:12 ` [PATCH 1/5] x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}() Peter Zijlstra
2019-02-27 16:14 ` Linus Torvalds
2019-02-27 16:48 ` Peter Zijlstra
2019-02-27 17:17 ` Linus Torvalds
2019-02-27 17:34 ` Peter Zijlstra
2019-02-27 17:38 ` Linus Torvalds
2019-02-27 17:57 ` Nadav Amit
2019-02-27 18:55 ` Nadav Amit
2019-02-27 19:41 ` Linus Torvalds
2019-03-08 13:35 ` Peter Zijlstra [this message]
2019-02-27 10:12 ` [PATCH 2/5] x86/percpu: Relax smp_processor_id() Peter Zijlstra
2019-02-27 10:12 ` [PATCH 3/5] x86/percpu, x86/irq: Relax {set,get}_irq_regs() Peter Zijlstra
2019-02-27 10:12 ` [PATCH 4/5] x86/percpu, x86/tlb: Relax cpu_tlbstate accesses Peter Zijlstra
2019-02-27 10:12 ` [PATCH 5/5] x86/percpu, sched/fair: Avoid local_clock() Peter Zijlstra
2019-02-27 10:24 ` [PATCH 6/5] x86/percpu: Optimize raw_cpu_xchg() Peter Zijlstra
2019-02-27 14:43 ` Peter Zijlstra
2019-02-27 23:16 ` [PATCH 0/5] x86/percpu semantics and fixes Nadav Amit
2019-03-08 14:50 ` Peter Zijlstra
2019-03-08 19:35 ` Nadav Amit
2019-03-08 20:56 ` Peter Zijlstra
2019-03-10 12:46 ` Peter Zijlstra
2019-03-08 22:48 ` Peter Zijlstra
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