From: Tejun Heo <tj@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/2] mm/sparse: add last_section_nr in sparse_init() to reduce some iteration cycle
Date: Sat, 11 Feb 2017 11:24:00 +0900 [thread overview]
Message-ID: <20170211022400.GA19050@mtj.duckdns.org> (raw)
In-Reply-To: <20170211021829.9646-2-richard.weiyang@gmail.com>
Hello,
On Sat, Feb 11, 2017 at 10:18:29AM +0800, Wei Yang wrote:
> During the sparse_init(), it iterate on each possible section. On x86_64,
> it would always be (2^19) even there is not much memory. For example, on a
> typical 4G machine, it has only (2^5) to (2^6) present sections. This
> benefits more on a system with smaller memory.
>
> This patch calculates the last section number from the highest pfn and use
> this as the boundary of iteration.
* How much does this actually matter? Can you measure the impact?
* Do we really need to add full reverse iterator to just get the
highest section number?
Thanks.
--
tejun
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next prev parent reply other threads:[~2017-02-11 2:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-11 2:18 [RFC PATCH 1/2] mm/memblock: introduce for_each_mem_pfn_range_rev() Wei Yang
2017-02-11 2:18 ` [RFC PATCH 2/2] mm/sparse: add last_section_nr in sparse_init() to reduce some iteration cycle Wei Yang
2017-02-11 2:24 ` Tejun Heo [this message]
2017-02-13 13:03 ` Wei Yang
2017-02-17 14:12 ` Wei Yang
2017-03-06 19:42 ` Tejun Heo
2017-03-08 8:00 ` Wei Yang
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