Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751062AbaLOWeU (ORCPT ); Mon, 15 Dec 2014 17:34:20 -0500 Received: from mail-pd0-f174.google.com ([209.85.192.174]:58473 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750892AbaLOWeT (ORCPT ); Mon, 15 Dec 2014 17:34:19 -0500 From: Kevin Hilman To: Dave Gerlach Cc: , , "Rafael J. Wysocki" , Pavel Machek , Len Brown , Nishanth Menon Subject: Re: [PATCH] PM QoS: Add debugfs support to view the list of constraints References: <1417799948-48440-1-git-send-email-d-gerlach@ti.com> Date: Mon, 15 Dec 2014 14:34:15 -0800 In-Reply-To: <1417799948-48440-1-git-send-email-d-gerlach@ti.com> (Dave Gerlach's message of "Fri, 5 Dec 2014 11:19:08 -0600") Message-ID: <7h1to0h7a0.fsf@deeprootsystems.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dave Gerlach writes: > From: Nishanth Menon > > PM QoS requests are notoriously hard to debug and made even > more so due to their highly dynamic nature. Having visibility > into the internal data representation per constraint allows > us to have much better appreciation of potential issues or > bad usage by drivers in the system. > > So introduce for all classes of PM QoS, an entry in > /sys/kernel/debug/pm_qos that shall show all the current > requests as well as the snapshot of the value these requests > boil down to. For example: > ==> /sys/kernel/debug/pm_qos/cpu_dma_latency <== > 1: 4444: Active > 2: 2000000000: Default > 3: 2000000000: Default > 4: 2000000000: Default > Type=Minimum, Value=4444, Requests: active=1 / total=4 > > ==> /sys/kernel/debug/pm_qos/memory_bandwidth <== > Empty! > > ... > > The actual value listed will have their meaning based > on the QoS it is on, the 'Type' indicates what logic > it would use to collate the information - Minimum, > Maximum, or Sum. Value is the collation of all requests. > This interface also compares the values with the defaults > for the QoS class and marks the ones that are > currently active. > > Signed-off-by: Nishanth Menon > Signed-off-by: Dave Gerlach A very useful feature indeed, Acked-by: Kevin Hilman Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/