From: Andrew Morton <akpm@linux-foundation.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org, Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: [PATCH v2 6/8] mm: Store compound_dtor / compound_order as bytes
Date: Wed, 20 Dec 2017 15:39:07 -0800 [thread overview]
Message-ID: <20171220153907.7f3994967cba32c6f654982c@linux-foundation.org> (raw)
In-Reply-To: <20171220155552.15884-7-willy@infradead.org>
On Wed, 20 Dec 2017 07:55:50 -0800 Matthew Wilcox <willy@infradead.org> wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
>
> Neither of these values get even close to 256; compound_dtor is
> currently at a maximum of 3, and compound_order can't be over 64.
> No machine has inefficient access to bytes since EV5, and while
> those are still supported, we don't optimise for them any more.
So we couild fit compound_dtor and compound_order into a single byte if
desperate?
> This does not shrink struct page, but it removes an ifdef and
> frees up 2-6 bytes for future use.
Can we add a little comment telling readers "hey there's a gap here!"?
--
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:[~2017-12-20 23:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-20 15:55 [PATCH v2 0/8] Restructure struct page Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 1/8] mm: Align struct page more aesthetically Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 2/8] mm: De-indent struct page Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 3/8] mm: Remove misleading alignment claims Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 4/8] mm: Improve comment on page->mapping Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 5/8] mm: Introduce _slub_counter_t Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 6/8] mm: Store compound_dtor / compound_order as bytes Matthew Wilcox
2017-12-20 23:39 ` Andrew Morton [this message]
2017-12-21 0:01 ` Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 7/8] mm: Document how to use struct page Matthew Wilcox
2017-12-20 15:55 ` [PATCH v2 8/8] mm: Remove reference to PG_buddy Matthew Wilcox
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=20171220153907.7f3994967cba32c6f654982c@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=linux-mm@kvack.org \
--cc=mawilcox@microsoft.com \
--cc=willy@infradead.org \
/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