From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: in_irq_or_nmi() Date: Mon, 27 Mar 2017 09:58:17 -0700 Message-ID: <20170327165817.GA28494@bombadil.infradead.org> References: <20170322234004.kffsce4owewgpqnm@techsingularity.net> <20170323144347.1e6f29de@redhat.com> <20170323145133.twzt4f5ci26vdyut@techsingularity.net> <779ab72d-94b9-1a28-c192-377e91383b4e@gmail.com> <1fc7338f-2b36-75f7-8a7e-8321f062207b@gmail.com> <2123321554.7161128.1490599967015.JavaMail.zimbra@redhat.com> <20170327105514.1ed5b1ba@redhat.com> <20170327143947.4c237e54@redhat.com> <20170327141518.GB27285@bombadil.infradead.org> <20170327171500.4beef762@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: Pankaj Gupta , Tariq Toukan , Mel Gorman , Tariq Toukan , netdev@vger.kernel.org, akpm@linux-foundation.org, linux-mm , Saeed Mahameed , linux-kernel@vger.kernel.org To: Jesper Dangaard Brouer Return-path: Content-Disposition: inline In-Reply-To: <20170327171500.4beef762@redhat.com> Sender: owner-linux-mm@kvack.org List-Id: netdev.vger.kernel.org On Mon, Mar 27, 2017 at 05:15:00PM +0200, Jesper Dangaard Brouer wrote: > And I also verified it worked: > > 0.63 │ mov __preempt_count,%eax > │ free_hot_cold_page(): > 1.25 │ test $0x1f0000,%eax > │ ↓ jne 1e4 > > And this simplification also made the compiler change this into a > unlikely branch, which is a micro-optimization (that I will leave up to > the compiler). Excellent! That said, I think we should define in_irq_or_nmi() in preempt.h, rather than hiding it in the memory allocator. And since we're doing that, we might as well make it look like the other definitions: diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 7eeceac52dea..af98c29abd9d 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -81,6 +81,7 @@ #define in_interrupt() (irq_count()) #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) #define in_nmi() (preempt_count() & NMI_MASK) +#define in_irq_or_nmi() (preempt_count() & (HARDIRQ_MASK | NMI_MASK)) #define in_task() (!(preempt_count() & \ (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET))) I think there are some genuine questions to be asked about the other users of in_irq() whether they really want to use in_irq_or_nmi(). There's fewer than a hundred of them, so somebody sufficiently motivated could take a look in a few days. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org