linux-kernel - Re: CPU Hotplug rework

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: <1332748920.16159.65.camel@twins>
Date:	Mon, 26 Mar 2012 10:02:00 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	paulmck@...ux.vnet.ibm.com,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Milton Miller <miltonm@....com>,
	"mingo@...e.hu" <mingo@...e.hu>, Tejun Heo <tj@...nel.org>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Linux PM mailing list <linux-pm@...r.kernel.org>
Subject: Re: CPU Hotplug rework

On Mon, 2012-03-26 at 11:11 +1030, Rusty Russell wrote:
> Obviously, having callbacks hanging around until the CPU comes back is
> not viable, nor is blocking preempt during the callbacks.  Calling
> get_online_cpus() is too heavy. 

-rt has patches (albeit somewhat ugly) to make get_online_cpus() a br
style rw-lock. That is, it makes the read side a per-cpu lock/counter so
that its much faster and only touches cpu-local state in the common
case.

It would be good to clean those up and make get_online_cpus() fast and
usable.
--
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/