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: <87d37gxbnc.fsf@abhimanyu.in.ibm.com>
Date:	Tue, 10 Apr 2012 13:26:55 +0530
From:	Nikunj A Dadhania <nikunj@...ux.vnet.ibm.com>
To:	paulmck@...ux.vnet.ibm.com,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arjan van de Ven <arjan@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"rusty\@rustcorp.com.au" <rusty@...tcorp.com.au>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	"akpm\@linux-foundation.org" <akpm@...ux-foundation.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Milton Miller <miltonm@....com>,
	"mingo\@elte.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, 9 Apr 2012 09:46:28 -0700, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> wrote:
> 
> > > 2.	Read and understand the architecture-specific code, looking
> > > 	for opportunities to consolidate additional function into
> > > 	core code.
> > > 
> > > 	a.	Carry out any indicated consolidation.
> > > 
> > > 	b.	Convert all architectures to make use of the
> > > 		consolidated implementation.
> > > 
> > > 	Not started.  Low priority from a big.LITTLE perspective.
> > 
> > 
> > Recently this unexpectedly assumed high priority due to some scheduler
> > changes and things got fixed up temporarily. And in that context,
> > Peter Zijlstra gave some more technical pointers on what is wrong and needs
> > to be done right. Link: https://lkml.org/lkml/2012/3/22/149
> > 
> > Nikunj (in CC) has offered to work with me on this consolidation.
> 
> Very cool!  I have added the following:
> 
> ------------------------------------------------------------------------
> 
> CONSOLIDATE ARCHITECTURE-SPECIFIC CPU-HOTPLUG CODE
> 
> 1.	Ensure that all CPU_STARTING notifiers complete before the
> 	incoming CPU is marked online (the blackfin architecture
> 	fails to do this).
> 
> 2.	Ensure that interrupts are disabled throughout the CPU_STARTING
> 	notifiers.  Currently, blackfin, cris, m32r, mips, sh, sparc64,
> 	um, and x86 fail to do this properly.
> 
> 3.	Ensure that all architectures that use CONFIG_USE_GENERIC_SMP_HELPERS
> 	hold ipi_call_lock() over the entire CPU-online process.  Currently,
> 	alpha, arm, m32r, mips, sh, and sparc32 seem to fail to do this
> 	properly.
> 
> 4.	Additional memory barriers are likely to be needed, for example,
> 	an smp_wmb() after setting cpu_active and an smp_rmb() in
> 	select_fallback_rq() before reading cpu_active.
> 
> Srivatsa Bhat (srivatsa.bhat@...ux.vnet.ibm.com) and Nikunj A Dadhania
> (nikunj@...ux.vnet.ibm.com) are taking on this work.
> 
Sounds good :-)

Regards
Nikunj

--
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/