linux-kernel - Re: [v8 PATCH 2/8]: cpuidle: implement a list based approach to register a set of idle routines.

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: <1254999033.26976.272.camel@twins>
Date:	Thu, 08 Oct 2009 12:50:33 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	arun@...ux.vnet.ibm.com
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Ingo Molnar <mingo@...e.hu>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Dipankar Sarma <dipankar@...ibm.com>,
	Balbir Singh <balbir@...ibm.com>,
	Arjan van de Ven <arjan@...radead.org>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-arch@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [v8 PATCH 2/8]: cpuidle: implement a list based approach to
 register a set of idle routines.

On Thu, 2009-10-08 at 16:12 +0530, Arun R Bharadwaj wrote:
> 
> > So cpuidle didn't already have a list of idle functions it takes an
> > appropriate one from?
> > 
> 
> No.. As of now, cpuidle supported only one _set_ of idle states that
> can be registered. So in this one set, it would choose the appropriate
> idle state. But this list mechanism(actually a stack) allows for
> multiple sets.
> 
> This is needed because we have a hierarchy of idle states discovery
> in x86. First, select_idle_routine() would select poll/mwait/default/c1e.
> It doesn't know of existance of ACPI. Later when ACPI comes up,
> it registers a set of routines on top of the earlier set.
> 
> > Then what does this governor do?
> >
> 
> The governor would only select the best idle state available from the
> set of states which is at the top of the stack. (In the above case, it
> would only consider the states registered by ACPI).
> 
> If the top-of-the-stack set of idle states is unregistered, the next
> set of states on the stack are considered.
> 
> > Also, does this imply the governor doesn't consider these idle routines?
> >
> 
> As i said above, governor would only consider the idle routines which
> are at the top of the stack.
> 
> Hope this gave a better idea..

So does it make sense to have a set of sets?

Why not integrate them all into one set to be ruled by this governor
thing?

--
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/