All of lore.kernel.org
 help / color / mirror / Atom feed
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>

  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 \
    --subject='Re: [PATCH v2 6/8] mm: Store compound_dtor / compound_order as bytes' \
    /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

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.