All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Giulio Benetti <giulio.benetti@benettiengineering.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Arnd Bergmann <arnd@arndb.de>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH v2 2/2] ARM: mm: convert empty_zero_page to array for consistency
Date: Wed, 19 Oct 2022 15:44:43 +0100	[thread overview]
Message-ID: <Y1ANW9ZRRPDJxlmc@shell.armlinux.org.uk> (raw)
In-Reply-To: <20221018222503.90118-2-giulio.benetti@benettiengineering.com>

On Wed, Oct 19, 2022 at 12:25:03AM +0200, Giulio Benetti wrote:
> ARM architecture is the only one to have empty_zero_page to be a
> struct page pointer, while in all other implementations empty_zero_page is
> a data pointer or directly an array(the zero page itself). So let's convert
> empty_zero_page to an array for consistency and to avoid an early
> allocation+dcache flush. Being the array in .bss it will be cleared earlier
> in a more linear way(and a bit faster) way.
> 
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>

I'm completely against this approach. It introduces inefficiencies in
paths we don't need, and also means that the zero page is at a fixed
location relative to the kernel, neither of which I like in the
slightest.

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Giulio Benetti <giulio.benetti@benettiengineering.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Arnd Bergmann <arnd@arndb.de>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH v2 2/2] ARM: mm: convert empty_zero_page to array for consistency
Date: Wed, 19 Oct 2022 15:44:43 +0100	[thread overview]
Message-ID: <Y1ANW9ZRRPDJxlmc@shell.armlinux.org.uk> (raw)
In-Reply-To: <20221018222503.90118-2-giulio.benetti@benettiengineering.com>

On Wed, Oct 19, 2022 at 12:25:03AM +0200, Giulio Benetti wrote:
> ARM architecture is the only one to have empty_zero_page to be a
> struct page pointer, while in all other implementations empty_zero_page is
> a data pointer or directly an array(the zero page itself). So let's convert
> empty_zero_page to an array for consistency and to avoid an early
> allocation+dcache flush. Being the array in .bss it will be cleared earlier
> in a more linear way(and a bit faster) way.
> 
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>

I'm completely against this approach. It introduces inefficiencies in
paths we don't need, and also means that the zero page is at a fixed
location relative to the kernel, neither of which I like in the
slightest.

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

  reply	other threads:[~2022-10-19 15:09 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-18 22:25 [PATCH v2 1/2] ARM: mm: fix no-MMU ZERO_PAGE() implementation Giulio Benetti
2022-10-18 22:25 ` Giulio Benetti
2022-10-18 22:25 ` [PATCH v2 2/2] ARM: mm: convert empty_zero_page to array for consistency Giulio Benetti
2022-10-18 22:25   ` Giulio Benetti
2022-10-19 14:44   ` Russell King (Oracle) [this message]
2022-10-19 14:44     ` Russell King (Oracle)
2022-10-19 16:29     ` Giulio Benetti
2022-10-19 16:29       ` Giulio Benetti
2022-11-04 20:07 ` [PATCH v2 1/2] ARM: mm: fix no-MMU ZERO_PAGE() implementation Giulio Benetti
2022-11-04 20:07   ` Giulio Benetti
2022-11-04 20:28   ` Arnd Bergmann
2022-11-04 20:28     ` Arnd Bergmann
2022-11-04 20:51     ` Giulio Benetti
2022-11-04 20:51       ` Giulio Benetti
2022-11-04 20:16 ` Arnd Bergmann
2022-11-04 20:16   ` Arnd Bergmann

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=Y1ANW9ZRRPDJxlmc@shell.armlinux.org.uk \
    --to=linux@armlinux.org.uk \
    --cc=akpm@linux-foundation.org \
    --cc=anshuman.khandual@arm.com \
    --cc=arnd@arndb.de \
    --cc=giulio.benetti@benettiengineering.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=wangkefeng.wang@huawei.com \
    --cc=will@kernel.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 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.