From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH] arm64: Implement cpu_relax as yield
Date: Wed, 25 Feb 2015 13:24:38 +0000 [thread overview]
Message-ID: <20150225132437.GD12377@arm.com> (raw)
In-Reply-To: <1424819257-22664-1-git-send-email-peter.crosthwaite@xilinx.com>
On Tue, Feb 24, 2015 at 11:07:37PM +0000, Peter Crosthwaite wrote:
> ARM64 has the yield nop hint which has the intended semantics of
> cpu_relax. Implement.
>
> The immediate application is ARM CPU emulators. An emulator can take
> advantage of the yield hint to de-prioritise an emulated CPU in favor
> of other emulation tasks. QEMU A64 SMP emulation has yield awareness,
> and sees a significant boot time performance increase with this change.
Could you elaborate on the QEMU SMP boot case please? Usually SMP pens
for booting make use of wfe/sev to minimise the spinning overhead.
Will
next prev parent reply other threads:[~2015-02-25 13:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-24 23:07 [RFC PATCH] arm64: Implement cpu_relax as yield Peter Crosthwaite
2015-02-25 13:24 ` Will Deacon [this message]
2015-02-27 19:43 ` Peter Crosthwaite
2015-02-27 19:53 ` Will Deacon
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=20150225132437.GD12377@arm.com \
--to=will.deacon@arm.com \
--cc=linux-arm-kernel@lists.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;
as well as URLs for NNTP newsgroup(s).