From: Tejun Heo <tj@kernel.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
mingo@elte.hu, tglx@linutronix.de, bphilips@suse.de,
yinghai@kernel.org, akpm@linux-foundation.org,
torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
jeff@garzik.org, linux-ide@vger.kernel.org,
stern@rowland.harvard.edu, gregkh@suse.de, khali@linux-fr.org
Subject: Re: [PATCH 09/12] irq: implement IRQ expecting
Date: Sat, 19 Jun 2010 11:03:24 +0200 [thread overview]
Message-ID: <4C1C87DC.6060405@kernel.org> (raw)
In-Reply-To: <20100619090031.GE18946@basil.fritz.box>
Hello,
On 06/19/2010 11:00 AM, Andi Kleen wrote:
>> IIUC, it's not to help or optimize polling itself. It just gives us a
>> way to estimate when the next interrupt would be so that power can be
>> optimized for non polling cases.
>
> Shouldn't the idle governour estimate this already?
I'm not an expert on the subject. According to Arjan,
One of the hard cases right now that the C state code has is that it
needs to predict the future. While it has a ton of heuristics,
including some is there IO oustanding" ones, libata is a really good
case: libata will know generally that within one seek time (5 msec
on rotating rust, much less on floating electrons) there'll be an
interrupt (give or take, but this is what we can do heuristics for
on a per irq level). So it's a good suggestion of what the future
will be like, MUCH better than any hint we have right now... all we
have right now is some history, and when the next timer is....
So, it seems like it would help.
Thanks.
--
tejun
next prev parent reply other threads:[~2010-06-19 9:04 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-13 15:31 [PATCHSET] irq: better lost/spurious irq handling Tejun Heo
2010-06-13 15:31 ` [PATCH 01/12] irq: cleanup irqfixup Tejun Heo
2010-06-13 15:31 ` [PATCH 02/12] irq: make spurious poll timer per desc Tejun Heo
2010-06-15 5:10 ` Konrad Rzeszutek Wilk
2010-06-15 16:34 ` Tejun Heo
2010-06-13 15:31 ` [PATCH 03/12] irq: use desc->poll_timer for irqpoll Tejun Heo
2010-06-13 15:31 ` [PATCH 04/12] irq: kill IRQF_IRQPOLL Tejun Heo
2010-06-13 15:31 ` [PATCH 05/12] irq: misc preparations for further changes Tejun Heo
2010-06-13 15:31 ` [PATCH 06/12] irq: implement irq_schedule_poll() Tejun Heo
2010-06-13 15:31 ` [PATCH 07/12] irq: improve spurious IRQ handling Tejun Heo
2010-06-13 15:31 ` [PATCH 08/12] irq: implement IRQ watching Tejun Heo
2010-06-13 15:31 ` [PATCH 09/12] irq: implement IRQ expecting Tejun Heo
2010-06-14 9:21 ` Jiri Slaby
2010-06-14 9:43 ` Tejun Heo
2010-06-14 9:46 ` Tejun Heo
2010-06-17 3:48 ` Arjan van de Ven
2010-06-17 8:18 ` Tejun Heo
2010-06-17 11:12 ` Thomas Gleixner
2010-06-17 11:23 ` Tejun Heo
2010-06-17 11:43 ` Alan Cox
2010-06-17 15:54 ` Tejun Heo
2010-06-17 16:02 ` Arjan van de Ven
2010-06-17 16:47 ` Tejun Heo
2010-06-18 6:26 ` Arjan van de Ven
2010-06-18 9:23 ` Tejun Heo
2010-06-18 9:45 ` Thomas Gleixner
2010-06-19 8:35 ` Andi Kleen
2010-06-19 8:42 ` Tejun Heo
2010-06-19 9:00 ` Andi Kleen
2010-06-19 9:03 ` Tejun Heo [this message]
2010-06-19 14:54 ` Arjan van de Ven
2010-06-19 19:49 ` Andi Kleen
2010-06-19 20:07 ` Arjan van de Ven
2010-06-13 15:31 ` [PATCH 10/12] irq: add comment about overall design of lost/spurious IRQ handling Tejun Heo
2010-06-13 15:31 ` [PATCH 11/12] libata: use IRQ expecting Tejun Heo
2010-06-13 15:31 ` [PATCH 12/12] usb: use IRQ watching Tejun Heo
2010-06-14 21:41 ` Greg KH
2010-06-14 21:52 ` Tejun Heo
2010-06-14 22:11 ` Greg KH
2010-06-14 22:19 ` Tejun Heo
2010-06-15 10:30 ` Kay Sievers
2010-06-15 11:05 ` Jean Delvare
2010-06-15 13:30 ` Kay Sievers
2010-06-15 11:20 ` Tejun Heo
2010-06-15 13:36 ` Kay Sievers
2010-06-15 17:36 ` Tejun Heo
2010-06-15 17:47 ` Greg KH
2010-06-15 17:52 ` Tejun Heo
2010-06-21 13:51 ` Tejun Heo
2010-06-21 20:27 ` Greg KH
2010-06-22 7:32 ` Tejun Heo
[not found] ` <1276443098-20653-12-git-send-email-tj@kernel.org>
2010-06-21 13:52 ` [PATCH 11/12] libata: use IRQ expecting Tejun Heo
2010-06-25 0:22 ` Jeff Garzik
2010-06-25 7:44 ` Tejun Heo
2010-06-25 9:48 ` Jeff Garzik
2010-06-25 9:51 ` Tejun Heo
2010-06-25 13:02 ` [PATCH 1/2 #upstream] sata_fsl,mv,nv: prepare for NCQ command completion update Tejun Heo
2010-06-25 13:03 ` [PATCH 2/2 #upstream] libata: always use ata_qc_complete_multiple() for NCQ command completions Tejun Heo
2010-08-17 22:03 ` Jeff Garzik
2010-08-01 23:47 ` [PATCH 1/2 #upstream] sata_fsl,mv,nv: prepare for NCQ command completion update Jeff Garzik
2010-08-02 7:18 ` Tejun Heo
2010-08-04 4:22 ` Jeff Garzik
2010-06-26 3:45 ` [PATCH 11/12] libata: use IRQ expecting Jeff Garzik
2010-06-26 3:52 ` Jeff Garzik
2010-06-26 8:31 ` Tejun Heo
2010-06-26 9:16 ` Jeff Garzik
2010-06-26 9:44 ` Tejun Heo
2010-07-02 14:41 ` Tejun Heo
2010-07-02 14:53 ` Tejun Heo
2010-07-10 10:06 ` Tejun Heo
2010-07-14 7:58 ` Jeff Garzik
2010-07-14 9:26 ` Tejun Heo
2010-07-27 17:37 ` Jeff Garzik
2010-07-02 14:59 ` [GIT PULL] irq: better lost/spurious irq handling Tejun Heo
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