From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965229AbcAUMiJ (ORCPT ); Thu, 21 Jan 2016 07:38:09 -0500 Received: from mail-wm0-f47.google.com ([74.125.82.47]:37240 "EHLO mail-wm0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965242AbcAUMiF (ORCPT ); Thu, 21 Jan 2016 07:38:05 -0500 Subject: Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings To: Peter Zijlstra 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> Cc: Thomas Gleixner , rafael@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, nicolas.pitre@linaro.org, vincent.guittot@linaro.org From: Daniel Lezcano Message-ID: <56A0D12A.1080007@linaro.org> Date: Thu, 21 Jan 2016 13:38:02 +0100 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20160121100834.GM6356@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/21/2016 11:08 AM, 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. Yep, that's correct. I was planning to re-work it later by handling the shared interrupts, assuming they were not so common, but regarding the examples below, that's wrong. >> 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 "," > 59: 0 0 0 0 0 0 > 0 0 0 0 0 0 0 > 0 0 0 0 0 0 0 > 0 0 0 0 0 0 0 > 0 0 0 0 0 0 0 > 0 0 0 0 0 0 IO-APIC > 5-fasteoi i801_smbus, i801_smbus > > root@wsm-ep:~# cat /proc/interrupts | grep "," > 18: 0 0 0 0 0 0 0 0 0 0 0 0 IO-APIC 18-fasteoi ehci_hcd:usb1, uhci_hcd:usb6 > 19: 9695230 19577242 13205011 3970578 740376 1138693 0 0 0 0 0 0 IO-APIC 19-fasteoi uhci_hcd:usb5, ata_piix > 23: 3 0 0 0 927 0 0 0 0 0 0 0 IO-APIC 23-fasteoi ehci_hcd:usb2, uhci_hcd:usb4 > > root@snb:~# cat /proc/interrupts | grep "," > 19: 11058485 0 0 0 0 0 0 0 IO-APIC 19-fasteoi ata_piix, ata_piix > > > Also there's a whole host of SOCs that has them. Ah, I see. Thank you very much for these examples. Sounds like, I have to handle the shared interrupts sooner than what I was expecting ... :) -- Daniel -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog