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Date: Wed, 4 May 2016 15:53:45 +0200
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>,
        Nicolas Pitre <nicolas.pitre@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Hildenbrand <dahi@linux.vnet.ibm.com>,
        Russell King <linux@arm.linux.org.uk>,
        lkml <linux-kernel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Subject: Re: kmap_atomic and preemption
Message-ID: <20160504155345.5fdd366e@free-electrons.com>
In-Reply-To: <20160504134729.GP3430@twins.programming.kicks-ass.net>
References: <5729D0F4.9090907@synopsys.com>
	<20160504134729.GP3430@twins.programming.kicks-ass.net>
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Hello,

On Wed, 4 May 2016 15:47:29 +0200, Peter Zijlstra wrote:

> static inline void *kmap_atomic(struct page *page)
> {
> 	preempt_disable();
> 	pagefault_disable();
> 	if (!PageHighMem(page))
> 		return page_address(page);
> 
> 	return __kmap_atomic(page);
> }

This is essentially what has been done on ARM in commit
9ff0bb5ba60638a688a46e93df8c5009896672eb, showing a pretty significant
improvement in network workloads.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com