linux-kernel - Re: [PATCH 2/3] memblock: Make finding index faster when modify regions.

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Date:   Mon, 16 Jan 2023 09:37:13 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     Peng Zhang <zhangpeng.00@...edance.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] memblock: Make finding index faster when modify
 regions.

On Mon, Jan 16, 2023 at 11:17:40AM +0800, Peng Zhang wrote:
> 
> 
> 在 2023/1/15 22:02, Mike Rapoport 写道:
> > Hi,
> > 
> > On Fri, Jan 13, 2023 at 04:26:58PM +0800, Peng Zhang wrote:
> > > We can use binary search to find the index to modify regions in
> > > memblock_add_range() and memblock_isolate_range(). Because the
> > > arrangement of regions is ordered. It may be faster when there are
> > > many regions. So implemented a binary search and a new macro to walk
> > > regions.
> > 
> > Did you see a measurable speedup with this optimization?
> > I'm not in favor of micro-optimizations that complicate code.
> > 
> Thank you for your reply. I haven't measured this patch yet, theoretically
> this small optimization might be difficult to observe.
> If you think this patch complicates the code, you can ignore this patch.
> 
> These three patches are independent and they can be applied independently.
> The logic of the third patch is very simple. It will not complicate the
> code. It is tested by the default configuration of qemu. The total number of
> iterations of memblock_merge_regions() in the third patch is reduced from
> more than one thousand to more than one hundred, this is only in the case of
> a small number of regions. Can you consider the third patch?

Can you please send the numbers and show how did you obtained them?

> Sincerely yours,
> Peng.

-- 
Sincerely yours,
Mike.