From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [RFC][PATCH 0/2 -mm] kexec based hibernation Date: Wed, 29 Aug 2007 12:41:25 +1000 Message-ID: <46D4DCD5.4030601@yahoo.com.au> References: <9D7649D18729DE4BB2BD7B494F7FEDC257EA60@pdsmsx415.ccr.corp.intel.com> <1188180997.3247.68.camel@caritas-dev.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1188180997.3247.68.camel@caritas-dev.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: "Huang, Ying" Cc: nigel@nigel.suspend2.net, Kexec Mailing List , linux-kernel@vger.kernel.org, "Eric W. Biederman" , linux-pm@lists.linux-foundation.org, Andrew Morton , Jeremy Maitin-Shepard List-Id: linux-pm@vger.kernel.org Huang, Ying wrote: > On Mon, 2007-08-27 at 09:28 +0800, Hu, Fenghua wrote: > >>One quick question is, can it improve hiberation/wakeup time? > > > In general, for kexec based hibernation, what increases > hibernation/wakeup time: > > - One extra Linux boot is needed to hibernate and wakeup. > > > What decreases hibernation/wakeup time: > > - Most hibernation/wakeup work is done in full functional user space > program, so it is possible to do some optimization, such as parallel > compression. - It does not have to reclaim pagecache before suspend? - It does not have to restore working set afterwards? (You could do this to reduce image size, of course, but it can be optional which is nice). > So, I think the kexec based hibernation may be slower than original > implementation in general. In this prototype implementation, the > hibernation/wakeup time is much longer than original hibernation/wakeup > implementation. But it has much to be optimized and I think it can > approach the speed of the original implementation after optimization. Also, don't just look at the time to do a simple suspend/resume cycle, but the full cost of going from working state to working state (eg. grep a kernel tree or two!). Although the kexec details are out of my league, I really like everything about the concept :) Nice work. -- SUSE Labs, Novell Inc.