From: Tejun Heo <tj@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: Andrew Morton <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: Mon, 6 Mar 2017 14:42:25 -0500 [thread overview]
Message-ID: <20170306194225.GB19696@htj.duckdns.org> (raw)
In-Reply-To: <CADZGycapTYxdxwHacFYiECZQ23uPDARQcahw_9zuKrNu-wG63g@mail.gmail.com>
Hello, Wei.
On Fri, Feb 17, 2017 at 10:12:31PM +0800, Wei Yang wrote:
> > And compare the ruling with the iteration for the loop to be (1UL <<
> > 5) and (1UL << 19).
> > The runtime is 0.00s and 0.04s respectively. The absolute value is not much.
systemd-analyze usually does a pretty good job of breaking down which
phase took how long. It might be worthwhile to test whether the
improvement is actually visible during the boot.
> >> * Do we really need to add full reverse iterator to just get the
> >> highest section number?
> >>
> >
> > You are right. After I sent out the mail, I realized just highest pfn
> > is necessary.
That said, getting efficient is always great as long as the added
complexity is justifiably small enough. If you can make the change
simple enough, it'd be a lot easier to merge.
Thanks.
--
tejun
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-03-06 19:42 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
2017-02-13 13:03 ` Wei Yang
2017-02-17 14:12 ` Wei Yang
2017-03-06 19:42 ` Tejun Heo [this message]
2017-03-08 8:00 ` 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=20170306194225.GB19696@htj.duckdns.org \
--to=tj@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=richard.weiyang@gmail.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox