From: Michal Hocko <mhocko@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [RESEND PATCH] base/memory: pass the base_section in add_memory_block
Date: Wed, 14 Jun 2017 08:30:38 +0200 [thread overview]
Message-ID: <20170614063038.GE6045@dhcp22.suse.cz> (raw)
In-Reply-To: <20170614060558.GA14009@WeideMBP.lan>
On Wed 14-06-17 14:05:58, Wei Yang wrote:
> Hi, Michael
>
> I copied your reply here:
>
> >[Sorry for a late response]
> >
> >On Wed 07-06-17 16:52:12, Wei Yang wrote:
> >> The second parameter of init_memory_block() is used to calculate the
> >> start_section_nr of this block, which means any section in the same block
> >> would get the same start_section_nr.
> >
> >Could you be more specific what is the problem here?
> >
>
> There is no problem in this code. I just find a unnecessary calculation and
> remove it in this patch.
This code needs a larger rething rather than here and there small
changes I believe.
> >> This patch passes the base_section to init_memory_block(), so that to
> >> reduce a local variable and a check in every loop.
> >
> >But then you are not handling a memblock which starts with a !present
> >section. The code is quite hairy but I do not see why your change is any
>
> I don't see the situation you pointed here.
>
> In add_memory_block(), section_nr is used to record the first section which is
> present. And this variable is used to calculate the section which is passed to
> init_memory_block().
>
> In init_memory_block(), the section got from add_memory_block(), is used to
> calculate scn_nr, but finally transformed to "start_section_nr". That means in
> init_memory_block(), we just need the "start_section_nr" of a memory_block. We
> don't care about who is the first present section.
You are right. The code is confusing as hell!
That being said, I am not opposing the patch but I would much rather
appreciate a consistent cleanup in the whole memblock vs. sections area.
That would be a larger project but the end result is really worth it.
--
Michal Hocko
SUSE Labs
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prev parent reply other threads:[~2017-06-14 6:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-14 5:45 [RESEND PATCH] base/memory: pass the base_section in add_memory_block Wei Yang
2017-06-14 5:59 ` Michal Hocko
2017-06-14 6:19 ` Wei Yang
2017-06-14 6:22 ` Michal Hocko
2017-06-14 6:05 ` Wei Yang
2017-06-14 6:30 ` Michal Hocko [this message]
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