From: Michal Hocko <mhocko@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: akpm@linux-foundation.org, tj@kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm/page_alloc: break on the first hit of mem range
Date: Wed, 28 Mar 2018 09:02:00 +0200 [thread overview]
Message-ID: <20180328070200.GC9275@dhcp22.suse.cz> (raw)
In-Reply-To: <20180328003936.GB91956@WeideMacBook-Pro.local>
On Wed 28-03-18 08:39:36, Wei Yang wrote:
> On Tue, Mar 27, 2018 at 12:58:21PM +0200, Michal Hocko wrote:
> >On Tue 27-03-18 11:57:07, Wei Yang wrote:
> >> find_min_pfn_for_node() iterate on pfn range to find the minimum pfn for a
> >> node. The memblock_region in memblock_type are already ordered, which means
> >> the first hit in iteration is the minimum pfn.
> >
> >I haven't looked at the code yet but the changelog should contain the
> >motivation why it exists. It seems like this is an optimization. If so,
> >what is the impact?
> >
>
> Yep, this is a trivial optimization on searching the minimal pfn on a special
> node. It would be better for audience to understand if I put some words in
> change log.
>
> The impact of this patch is it would accelerate the searching process when
> there are many memory ranges in memblock.
>
> For example, in the case https://lkml.org/lkml/2018/3/25/291, there are around
> 30 memory ranges on node 0. The original code need to iterate all those ranges
> to find the minimal pfn, while after optimization it just need once.
Then show us some numbers to justify the change.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-03-28 7:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-27 3:57 [PATCH] mm/page_alloc: break on the first hit of mem range Wei Yang
2018-03-27 10:58 ` Michal Hocko
2018-03-28 0:39 ` Wei Yang
2018-03-28 7:02 ` Michal Hocko [this message]
2018-03-28 13:17 ` Wei Yang
2018-03-27 22:47 ` Andrew Morton
2018-03-28 0:51 ` Wei Yang
2018-03-28 1:37 ` Andrew Morton
2018-03-28 3:44 ` Wei Yang
2018-03-28 3:47 ` [PATCH] mm/page_alloc: optimize find_min_pfn_for_node() by geting the minimal pfn directly Wei Yang
2018-03-28 11:58 ` Michal Hocko
2018-03-28 13:34 ` Wei Yang
2018-03-28 14:02 ` Michal Hocko
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