Revision 83dac59409387789b88bed40b1be86a8abc572be authored by Deepthi Dharwar on 03 October 2012, 18:42:26 UTC, committed by Benjamin Herrenschmidt on 17 October 2012, 23:57:25 UTC
Earlier without cpuidle framework on pseries, the native arch idle routine comprised of both snooze and nap states. smt_snooze_delay variable was used to delay the idle process entry to deeper idle state like nap. With the coming of cpuidle, this arch specific idle was replaced by two different idle routines, one for supporting snooze and other for nap. This enabled addition of more low level idle states on pseries in the future. On adopting the generic cpuidle framework for POWER systems, the decision of which idle state to choose from, given a predicted idle time is taken by the menu governor based on target_residency and exit_latency of the idle states. target_residency is the minimum time to be resident in that idle state. Exit_latency is time taken to exit out of idle state. Deeper the idle state, both the target residency and exit latency would be higher. In the current design, smt_snooze_delay is used as target_residency for the snooze state which is incorrect, as it is not the minimum but the maximum duration to be in snooze state. This would result in the governor in taking bad decision, as presently target_residency of nap < target_residency of snooze inspite of nap being deeper idle state. This patch aims to fix this problem by replacing the smt_snooze_delay loop in snooze state, with the need_resched() as the governor is aware of entry and exit of various idle transitions based on which next idle time prediction. The governor is intelligent enough to determine the idle state the needs to be transitioned to and maintains a whole of heuristics including io load, previous idle states predictions etc for the same, based on which idle state entry decision is taken. With this fix, of setting target_residency of snooze to 0 nap to smt_snooze_delay if the predicted idle time is less than smt_snooze_delay (target_residency of nap) value governor would pick snooze state, else nap. This adhers to the previous native idle design. Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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# This list is used by git-shortlog to fix a few botched name translations
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Aaron Durbin <adurbin@google.com>
Adam Oldham <oldhamca@gmail.com>
Adam Radford <aradford@gmail.com>
Adrian Bunk <bunk@stusta.de>
Alan Cox <alan@lxorguk.ukuu.org.uk>
Alan Cox <root@hraefn.swansea.linux.org.uk>
Aleksey Gorelov <aleksey_gorelov@phoenix.com>
Al Viro <viro@ftp.linux.org.uk>
Al Viro <viro@zenIV.linux.org.uk>
Andreas Herrmann <aherrman@de.ibm.com>
Andrew Morton <akpm@osdl.org>
Andrew Vasquez <andrew.vasquez@qlogic.com>
Andy Adamson <andros@citi.umich.edu>
Archit Taneja <archit@ti.com>
Arnaud Patard <arnaud.patard@rtp-net.org>
Arnd Bergmann <arnd@arndb.de>
Axel Dyks <xl@xlsigned.net>
Axel Lin <axel.lin@gmail.com>
Ben Gardner <bgardner@wabtec.com>
Ben M Cahill <ben.m.cahill@intel.com>
Björn Steinbrink <B.Steinbrink@gmx.de>
Brian Avery <b.avery@hp.com>
Brian King <brking@us.ibm.com>
Christoph Hellwig <hch@lst.de>
Corey Minyard <minyard@acm.org>
Damian Hobson-Garcia <dhobsong@igel.co.jp>
David Brownell <david-b@pacbell.net>
David Woodhouse <dwmw2@shinybook.infradead.org>
Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Domen Puncer <domen@coderock.org>
Douglas Gilbert <dougg@torque.net>
Ed L. Cashin <ecashin@coraid.com>
Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Felipe W Damasio <felipewd@terra.com.br>
Felix Kuhling <fxkuehl@gmx.de>
Felix Moeller <felix@derklecks.de>
Filipe Lautert <filipe@icewall.org>
Franck Bui-Huu <vagabon.xyz@gmail.com>
Frank Zago <fzago@systemfabricworks.com>
Greg Kroah-Hartman <greg@echidna.(none)>
Greg Kroah-Hartman <gregkh@suse.de>
Greg Kroah-Hartman <greg@kroah.com>
Henk Vergonet <Henk.Vergonet@gmail.com>
Henrik Kretzschmar <henne@nachtwindheim.de>
Herbert Xu <herbert@gondor.apana.org.au>
Jacob Shin <Jacob.Shin@amd.com>
James Bottomley <jejb@mulgrave.(none)>
James Bottomley <jejb@titanic.il.steeleye.com>
James E Wilson <wilson@specifix.com>
James Ketrenos <jketreno@io.(none)>
Jean Tourrilhes <jt@hpl.hp.com>
Jeff Garzik <jgarzik@pretzel.yyz.us>
Jens Axboe <axboe@suse.de>
Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
John Stultz <johnstul@us.ibm.com>
Juha Yrjola <at solidboot.com>
Juha Yrjola <juha.yrjola@nokia.com>
Juha Yrjola <juha.yrjola@solidboot.com>
Kay Sievers <kay.sievers@vrfy.org>
Kenneth W Chen <kenneth.w.chen@intel.com>
Koushik <raghavendra.koushik@neterion.com>
Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Leonid I Ananiev <leonid.i.ananiev@intel.com>
Linas Vepstas <linas@austin.ibm.com>
Mark Brown <broonie@sirena.org.uk>
Matthieu CASTET <castet.matthieu@free.fr>
Mayuresh Janorkar <mayur@ti.com>
Michael Buesch <m@bues.ch>
Michel Dänzer <michel@tungstengraphics.com>
Mitesh shah <mshah@teja.com>
Morten Welinder <terra@gnome.org>
Morten Welinder <welinder@anemone.rentec.com>
Morten Welinder <welinder@darter.rentec.com>
Morten Welinder <welinder@troll.com>
Mythri P K <mythripk@ti.com>
Nguyen Anh Quynh <aquynh@gmail.com>
Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Patrick Mochel <mochel@digitalimplant.org>
Peter A Jonsson <pj@ludd.ltu.se>
Peter Oruba <peter@oruba.de>
Peter Oruba <peter.oruba@amd.com>
Praveen BP <praveenbp@ti.com>
Rajesh Shah <rajesh.shah@intel.com>
Ralf Baechle <ralf@linux-mips.org>
Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
Rémi Denis-Courmont <rdenis@simphalempin.com>
Rudolf Marek <R.Marek@sh.cvut.cz>
Rui Saraiva <rmps@joel.ist.utl.pt>
Sachin P Sant <ssant@in.ibm.com>
Sam Ravnborg <sam@mars.ravnborg.org>
Sascha Hauer <s.hauer@pengutronix.de>
S.Çağlar Onur <caglar@pardus.org.tr>
Simon Kelley <simon@thekelleys.org.uk>
Stéphane Witzmann <stephane.witzmann@ubpmes.univ-bpclermont.fr>
Stephen Hemminger <shemminger@osdl.org>
Sumit Semwal <sumit.semwal@ti.com>
Tejun Heo <htejun@gmail.com>
Thomas Graf <tgraf@suug.ch>
Tony Luck <tony.luck@intel.com>
Tsuneo Yoshioka <Tsuneo.Yoshioka@f-secure.com>
Uwe Kleine-König <ukleinek@informatik.uni-freiburg.de>
Uwe Kleine-König <ukl@pengutronix.de>
Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Viresh Kumar <viresh.linux@gmail.com> <viresh.kumar@st.com>
Takashi YOSHII <takashi.yoshii.zj@renesas.com>
Yusuke Goda <goda.yusuke@renesas.com>
Gustavo Padovan <gustavo@las.ic.unicamp.br>
Gustavo Padovan <padovan@profusion.mobi>
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