From: Christoph Hellwig <hch@infradead.org>
To: Bean Huo <huobean@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
beanhuo@micron.com, Richard Weinberger <richard@nod.at>
Subject: Re: [PATCH RFC] mm: Let readahead submit larger batches of pages in case of ra->ra_pages == 0
Date: Fri, 11 Sep 2020 10:47:09 +0100 [thread overview]
Message-ID: <20200911094709.GB14158@infradead.org> (raw)
In-Reply-To: <ef82be594709a8f954f4933968bd96888e589df3.camel@gmail.com>
On Fri, Sep 11, 2020 at 10:15:24AM +0200, Bean Huo wrote:
> > What is special about ->ra_pages==0? Wouldn't this optimization
> > still
> > be valid if ->ra_pages==2?
> >
> > Doesn't this defeat the purpose of having ->ra_pages==0?
>
>
> Hi Andrew
> Sorry, I am still not quite understanding your above three questions.
>
> Based on my shallow understanding, ra_pages is associated with
> read_ahead_kb. Seems ra_pages controls the maximum read-ahead window
> size, but it doesn't work when the requested size exceeds ra_pages.
>
> If I set the read_ahead_kb to 0, also, as Christoph mentioned, MTD
> forcibly sets ra_pages to 0. I think the intention is that only wants
> to disable read-ahead, however, doesn't want
> generic_file_buffered_read() to split the request and read data with
> 4KB chunk size separately.
They way I understood Richard this is intentional.
next prev parent reply other threads:[~2020-09-11 9:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 14:48 Bean Huo
2020-09-04 18:09 ` Andrew Morton
2020-09-11 8:15 ` Bean Huo
2020-09-11 9:47 ` Christoph Hellwig [this message]
2020-09-11 11:35 ` Bean Huo
2020-09-11 11:36 ` Bean Huo
2020-09-07 7:16 ` Christoph Hellwig
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=20200911094709.GB14158@infradead.org \
--to=hch@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=beanhuo@micron.com \
--cc=huobean@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=richard@nod.at \
/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