linux-kernel - Re: [PATCH 1/2] cpuhotplug/nohz: Remove offline cpus from nohz-idle state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130105103627.GU2631@n2100.arm.linux.org.uk>
Date:	Sat, 5 Jan 2013 10:36:27 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Srivatsa Vaddagiri <vatsa@...eaurora.org>
Cc:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-arm-kernel@...ts.infradead.org,
	Mike Frysinger <vapier@...too.org>,
	uclinux-dist-devel@...ckfin.uclinux.org,
	Ralf Baechle <ralf@...ux-mips.org>, linux-mips@...ux-mips.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linuxppc-dev@...ts.ozlabs.org,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	linux-s390@...r.kernel.org, Paul Mundt <lethal@...ux-sh.org>,
	linux-sh@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	sparclinux@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org, mhocko@...e.cz,
	srivatsa.bhat@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 1/2] cpuhotplug/nohz: Remove offline cpus from
	nohz-idle state

On Thu, Jan 03, 2013 at 06:58:38PM -0800, Srivatsa Vaddagiri wrote:
> I also think that the
> wait_for_completion() based wait in ARM's __cpu_die() can be replaced with a
> busy-loop based one, as the wait there in general should be terminated within
> few cycles.

Why open-code this stuff when we have infrastructure already in the kernel
for waiting for stuff to happen?  I chose to use the standard infrastructure
because its better tested, and avoids having to think about whether we need
CPU barriers and such like to ensure that updates are seen in a timely
manner.

My stance on a lot of this idle/cpu dying code is that much of it can
probably be cleaned up and merged into a single common implementation -
in which case the use of standard infrastructure for things like waiting
for other CPUs do stuff is even more justified.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/