From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx102.postini.com [74.125.245.102]) by kanga.kvack.org (Postfix) with SMTP id 891366B004D for ; Wed, 28 Nov 2012 04:47:20 -0500 (EST) Received: from mail-ea0-f169.google.com ([209.85.215.169]) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_ARCFOUR_SHA1:16) (Exim 4.71) (envelope-from ) id 1TdeEh-0003HZ-FV for linux-mm@kvack.org; Wed, 28 Nov 2012 09:47:19 +0000 Received: by mail-ea0-f169.google.com with SMTP id a12so5458721eaa.14 for ; Wed, 28 Nov 2012 01:47:19 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1408044.6czCGhbHJH@vostro.rjw.lan> References: <1353761958-12810-1-git-send-email-ming.lei@canonical.com> <5434404.G1ERYjuorE@vostro.rjw.lan> <1408044.6czCGhbHJH@vostro.rjw.lan> Date: Wed, 28 Nov 2012 17:47:18 +0800 Message-ID: Subject: Re: [PATCH v6 2/6] PM / Runtime: introduce pm_runtime_set_memalloc_noio() From: Ming Lei Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: "Rafael J. Wysocki" Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Alan Stern , Oliver Neukum , Minchan Kim , Greg Kroah-Hartman , Jens Axboe , "David S. Miller" , Andrew Morton , netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-mm@kvack.org On Wed, Nov 28, 2012 at 5:29 PM, Rafael J. Wysocki wrote: > > But it doesn't have to walk the children. Moreover, with counters it only Yeah, I got it, it is the advantage of counter, but with extra 'int' field introduced in 'struct device'. > needs to walk the whole path if all devices in it need to be updated. For > example, if you call pm_runtime_set_memalloc_noio(dev, true) for a device > whose parent's counter is greater than zero already, you don't need to > walk the path above the parent. We still can do it with the flag only, pm_runtime_set_memalloc_noio(dev, true) can return immediately if one parent or the 'dev' flag is true. But considered that the pm_runtime_set_memalloc_noio(dev, false) is only called in a very infrequent path(network/block device->remove()), looks the introduced cost isn't worthy of the obtained advantage. So could you accept not introducing counter? and I will update with the above improvement you suggested. Thanks, -- Ming Lei -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org