From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH 1/1] suspend: make sync() on suspend-to-RAM optional Date: Wed, 15 Jul 2015 08:43:21 +0200 Message-ID: <20150715064320.GA23713@amd> References: <1436927091-32520-1-git-send-email-lenb@kernel.org> <505338dbbcdce9416ac05f67288b10442fbda179.1436926113.git.len.brown@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <505338dbbcdce9416ac05f67288b10442fbda179.1436926113.git.len.brown@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Len Brown Cc: rjw@rjwysocki.net, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Len Brown List-Id: linux-pm@vger.kernel.org On Tue 2015-07-14 22:24:51, Len Brown wrote: > From: Len Brown > > The Linux kernel suspend path has traditionally invoked sys_sync(). > > But sys_sync() can be expensive, and some systems do not want > to pay the cost of sys_sync() on every suspend. Have you measured how expesive it can be, and why it is expensive? > So make sys_sync on suspend optional. > > Create sysfs attribute /sys/power/pm_suspend_do_sync. > When set to 1, the kernel will sys_sync() on suspend, > When set to 0, it will not. > > This attribute can be changed by root at run-time. > Kernel build parameter CONFIG_PM_SUSPEND_DO_SYNC_DEFAULT. > As this is 1, by default, this patch does not change > default behavior. Why do you need CONFIG parameter? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html