From: Oscar Salvador <osalvador@techadventures.net>
To: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>,
akpm@linux-foundation.org, rientjes@google.com,
linux-mm@kvack.org, kirill.shutemov@linux.intel.com,
bob.picco@hp.com
Subject: Re: [PATCH 3/3] mm/sparse: use __highest_present_section_nr as the boundary for pfn check
Date: Thu, 23 Aug 2018 22:52:48 +0200 [thread overview]
Message-ID: <20180823205248.GA22452@techadventures.net> (raw)
In-Reply-To: <20180823191729.GQ29735@dhcp22.suse.cz>
On Thu, Aug 23, 2018 at 09:17:29PM +0200, Michal Hocko wrote:
> And how exactly does it help to check for the smaller vs. a larger number?
> Both are O(1) operations AFAICS. __highest_present_section_nr makes
> perfect sense when we iterate over all sections or similar operations
> where it smaller number of iterations really makes sense.
Sure, improvement/optimization was not really my point, a comparasion is
a comparasion.
The gain, if any, would be because we would catch
non present sections sooner before calling to present_section().
In the case that __highest_present_section_nr differs from
NR_MEM_SECTIONS, of course.
I thought it would make more sense given the nature of the function itself.
The only thing I did not like much was that we need to export the symbol, though.
So, as you said, the price might be too hight for what we get.
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2018-08-23 20:52 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-23 13:07 [PATCH 0/3] trivial code refine for sparsemem Wei Yang
2018-08-23 13:07 ` [PATCH 1/3] mm/sparse: add likely to mem_section[root] check in sparse_index_init() Wei Yang
2018-08-23 13:13 ` Michal Hocko
2018-08-23 22:57 ` Wei Yang
2018-08-24 7:31 ` Michal Hocko
2018-08-24 0:11 ` Dave Hansen
2018-08-24 15:07 ` Wei Yang
2018-09-03 22:27 ` Wei Yang
2018-09-09 1:38 ` Wei Yang
2018-09-10 20:30 ` Dave Hansen
2018-09-11 15:00 ` Wei Yang
2018-08-23 13:07 ` [PATCH 2/3] mm/sparse: expand the CONFIG_SPARSEMEM_EXTREME range in __nr_to_section() Wei Yang
2018-08-23 13:21 ` Michal Hocko
2018-08-23 23:03 ` Wei Yang
2018-08-24 0:09 ` Dave Hansen
2018-08-24 15:24 ` Wei Yang
2018-08-23 13:07 ` [PATCH 3/3] mm/sparse: use __highest_present_section_nr as the boundary for pfn check Wei Yang
2018-08-23 13:25 ` Michal Hocko
2018-08-23 14:00 ` Oscar Salvador
2018-08-23 19:17 ` Michal Hocko
2018-08-23 20:52 ` Oscar Salvador [this message]
2018-08-24 0:15 ` Dave Hansen
2018-08-24 18:11 ` Wei Yang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180823205248.GA22452@techadventures.net \
--to=osalvador@techadventures.net \
--cc=akpm@linux-foundation.org \
--cc=bob.picco@hp.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=richard.weiyang@gmail.com \
--cc=rientjes@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.