From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Date: Thu, 21 Jan 2016 21:27:11 +0100 (CET) Message-ID: References: <1453305636-22156-1-git-send-email-daniel.lezcano@linaro.org> <1453305636-22156-2-git-send-email-daniel.lezcano@linaro.org> <20160120190718.GS6357@twins.programming.kicks-ass.net> <56A0A9E3.2070306@linaro.org> <20160121100834.GM6356@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from www.linutronix.de ([62.245.132.108]:41032 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751277AbcAUU2O (ORCPT ); Thu, 21 Jan 2016 15:28:14 -0500 In-Reply-To: <20160121100834.GM6356@twins.programming.kicks-ass.net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Peter Zijlstra Cc: Daniel Lezcano , rafael@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, nicolas.pitre@linaro.org, vincent.guittot@linaro.org On Thu, 21 Jan 2016, Peter Zijlstra wrote: > On Thu, Jan 21, 2016 at 10:50:27AM +0100, Daniel Lezcano wrote: > > > Actually, the handle passes dev_id in order to let the irqtimings to sort > > out a shared interrupt and prevent double sampling. In other words, for > > shared interrupts, statistics should be per t-uple(irq , dev_id) but that is > > something I did not implemented ATM. > > > > IMO, the handler is at the right place. The prediction code does not take > > care of the shared interrupts yet. > > That certainly added to the confusion. But if you want per dev_id stats, > the whole alloc framework is 'broken' too, for it allocates the stuff > per irq. > > > I tried to find a platform with shared interrupts in the ones I have > > available around me but I did not find any. Are the shared interrupts > > something used nowadays or coming from legacy hardware ? What is the > > priority to handle the shared interrupts in the prediction code ? > > They're less common (thankfully) than they used to be, but I still have > them: > > root@ivb-ep:~# cat /proc/interrupts | grep "," > 0 IO-APIC 5-fasteoi i801_smbus, i801_smbus Hardly something which is worth to add the extra complexity. > root@wsm-ep:~# cat /proc/interrupts | grep "," > 18: 0 0 IO-APIC 18-fasteoi ehci_hcd:usb1, uhci_hcd:usb6 > 23: 3 927 IO-APIC 23-fasteoi ehci_hcd:usb2, uhci_hcd:usb4 Stick the USB thingy into the XHCI port :) > 19: 9695230 19577242 .... IO-APIC 19-fasteoi uhci_hcd:usb5, ata_piix > root@snb:~# cat /proc/interrupts | grep "," > 19: 11058485 IO-APIC 19-fasteoi ata_piix, ata_piix Go to the BIOS and enable AHCI mode. Both the snb and the wsm-ep chipsets can be switched between legacy piix and ahci mode :) You seem to have a faible for last century hardware. > Also there's a whole host of SOCs that has them. And one of the reasons is, that a lot of drivers do not support msi, while these embedded beasts support MSI on almost every peripheral, at least the newer ones. Thanks, tglx