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Date: Fri, 5 Jun 2015 11:14:48 +0800
From: Xishi Qiu <qiuxishi@huawei.com>
MIME-Version: 1.0
Subject: Re: [RFC PATCH 10/12] mm: add the buddy system interface
References: <55704A7E.5030507@huawei.com> <55704CC4.8040707@huawei.com> <3908561D78D1C84285E8C5FCA982C28F32A8D5C7@ORSMSX114.amr.corp.intel.com>
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To: "Luck, Tony" <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, "nao.horiguchi@gmail.com" <nao.horiguchi@gmail.com>, Yinghai Lu <yinghai@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, "mingo@elte.hu" <mingo@elte.hu>, Xiexiuqi <xiexiuqi@huawei.com>, Hanjun Guo <guohanjun@huawei.com>, Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>

On 2015/6/5 1:09, Luck, Tony wrote:

> +#ifdef CONFIG_MEMORY_MIRROR
> +	if (change_to_mirror(gfp_mask, ac.high_zoneidx))
> +		ac.migratetype = MIGRATE_MIRROR;
> +#endif
> 
> We may have to be smarter than this here. I'd like to encourage the
> enterprise Linux distributions to set CONFIG_MEMORY_MIRROR=y
> But the reality is that most systems will not configure any mirrored
> memory - so we don't want the common code path for memory
> allocation to call functions that set the migrate type, try to allocate
> and then fall back to a non-mirror when that may be a complete waste
> of time.
> 
> Maybe a global "got_mirror" that is true if we have some mirrored
> memory.  Then code is
> 
> 	if (got_mirror && change_to_mirror(...))
> 

Yes, I will change next time.

Thanks,

> .
> 



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