linux-kernel - Re: [tip:x86/mm] percpu: Introduce a read-mostly percpu API

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Date:	Wed, 20 Oct 2010 19:53:17 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Shaohua Li <shaohua.li@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"eric.dumazet@...il.com" <eric.dumazet@...il.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...ux.intel.com" <hpa@...ux.intel.com>
Subject: Re: [tip:x86/mm] percpu: Introduce a read-mostly percpu API

I know, but I can't do that immediately.  It is an optimizatiin we can do for .38.

"Shaohua Li" <shaohua.li@...el.com> wrote:

>Hi hpa,
>On Thu, Oct 21, 2010 at 07:06:59AM +0800, tip-bot for Shaohua Li wrote:
>> [ hpa: moved it *after* the page-aligned section, for obvious
>>   reasons. ]
>move it after page-aligned section can't guarantee to avoid cache false
>sharing.
>we need:
>. = ALIGN(CACHE_LINE_SIZE);
>*(.data..percpu..readmostly)
>. = ALIGN(CACHE_LINE_SIZE);
>To make sure before/after readmostly section doesn't share cache line
>with
>others. The headcache is some arch need L1_CACHE_SIZE and others need
>(1 << INTERNODE_CACHE_SHIFT). We need change all ARCHs to make this
>happen.

-- 
Sent from my mobile phone.  Please pardon any lack of formatting.
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