From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757611Ab2AESqJ (ORCPT ); Thu, 5 Jan 2012 13:46:09 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:55211 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754713Ab2AESqH (ORCPT ); Thu, 5 Jan 2012 13:46:07 -0500 Date: Thu, 5 Jan 2012 19:46:05 +0100 From: Pavel Machek To: Barry Song <21cnbao@gmail.com> Cc: Barry Song , rjw@sisk.pl, linux-pm@lists.linux-foundation.org, workgroup.linux@csr.com, Xiangzhen Ye , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Barry Song Subject: Re: [PATCH v2] PM: HIBERNATION: skip the swap size check if the snapshot image size is anticipative Message-ID: <20120105184604.GA11065@atrey.karlin.mff.cuni.cz> References: <1322208422-12346-1-git-send-email-Barry.Song@csr.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-2 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! Is the check even useful these days? Should we remove it altogether? Pavel > Pavel ,Rafael, any feedback? > -barry > > 2011/11/25 Barry Song : > > From: Barry Song > > > > Current swsusp requires swap partitions even larger than real saved pages > > based on the worst compression ratio: > > but for an embedded system, which has limited storage space, then it might > > can't give the large partition to save snapshot. > > In the another way, some embedded systems can definitely know the most size > > needed for snapshot since they run some specific application lists. > > So this patch provides the possibility for users to tell kernel even > > the system has a little snapshot partition, but it is still enough. > > For example, if the system need to save 120MB memory, origin swsusp will require > > a 130MB partition to save snapshot. but if users know 30MB is enough for them( > > compressed image will be less than 30MB), they just make a 30MB partition by > > echo 0 > /sys/power/check_swap_size > > > > Signed-off-by: Barry Song > > Cc: Xiangzhen Ye > > --- > >  -v2:drop swap_enough bootargs and use /sys/power/check_swap_size node > > > >  Documentation/power/interface.txt |    5 +++++ > >  kernel/power/hibernate.c          |   22 ++++++++++++++++++++++ > >  kernel/power/power.h              |    2 ++ > >  kernel/power/swap.c               |    9 +++++++++ > >  4 files changed, 38 insertions(+), 0 deletions(-) > > > > diff --git a/Documentation/power/interface.txt b/Documentation/power/interface.txt > > index c537834..5e205f0 100644 > > --- a/Documentation/power/interface.txt > > +++ b/Documentation/power/interface.txt > > @@ -47,6 +47,11 @@ Writing to this file will accept one of > >        'testproc' > >        'test' > > > > +/sys/power/check_swap_size controls whether we can skip checking the swap > > +partition size by worst compression ratio. If users know the swap partition > > +is enough for compressed snapshot, write 0 to /sys/power/check_swap_size. > > +It is useful for an embedded system with known running softwares. > > + > >  /sys/power/image_size controls the size of the image created by > >  the suspend-to-disk mechanism.  It can be written a string > >  representing a non-negative integer that will be used as an upper > > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c > > index 1c53f7f..5552473 100644 > > --- a/kernel/power/hibernate.c > > +++ b/kernel/power/hibernate.c > > @@ -1024,11 +1024,33 @@ static ssize_t reserved_size_store(struct kobject *kobj, > > > >  power_attr(reserved_size); > > > > +static ssize_t check_swap_size_show(struct kobject *kobj, struct kobj_attribute *attr, > > +                              char *buf) > > +{ > > +       return sprintf(buf, "%d\n", check_swap_size); > > +} > > + > > +static ssize_t check_swap_size_store(struct kobject *kobj, struct kobj_attribute *attr, > > +                               const char *buf, size_t n) > > +{ > > +       int check_size; > > + > > +       if (sscanf(buf, "%d", &check_size) == 1) { > > +               check_swap_size = check_size; > > +               return n; > > +       } > > + > > +       return -EINVAL; > > +} > > + > > +power_attr(check_swap_size); > > + > >  static struct attribute * g[] = { > >        &disk_attr.attr, > >        &resume_attr.attr, > >        &image_size_attr.attr, > >        &reserved_size_attr.attr, > > +       &check_swap_size_attr.attr, > >        NULL, > >  }; > > > > diff --git a/kernel/power/power.h b/kernel/power/power.h > > index 23a2db1..4f0fa78 100644 > > --- a/kernel/power/power.h > > +++ b/kernel/power/power.h > > @@ -74,6 +74,8 @@ static struct kobj_attribute _name##_attr = { \ > > > >  /* Preferred image size in bytes (default 500 MB) */ > >  extern unsigned long image_size; > > +/* If 0, skip checking whether the swap size is enough for compressed snapshot */ > > +extern int check_swap_size; > >  /* Size of memory reserved for drivers (default SPARE_PAGES x PAGE_SIZE) */ > >  extern unsigned long reserved_size; > >  extern int in_suspend; > > diff --git a/kernel/power/swap.c b/kernel/power/swap.c > > index 11a594c..db90195 100644 > > --- a/kernel/power/swap.c > > +++ b/kernel/power/swap.c > > @@ -37,6 +37,12 @@ > >  #define HIBERNATE_SIG  "S1SUSPEND" > > > >  /* > > + * if users know swap partitions are enough for compressed snapshots, > > + * echo 0 > /sys/power/check_swap_size > > + */ > > +int check_swap_size = 1; > > + > > +/* > >  *     The swap map is a data structure used for keeping track of each page > >  *     written to a swap partition.  It consists of many swap_map_page > >  *     structures that contain each an array of MAP_PAGE_ENTRIES swap entries. > > @@ -772,6 +778,9 @@ static int enough_swap(unsigned int nr_pages, unsigned int flags) > >        unsigned int free_swap = count_swap_pages(root_swap, 1); > >        unsigned int required; > > > > +       if (!check_swap_size) > > +               return 1; > > + > >        pr_debug("PM: Free swap pages: %u\n", free_swap); > > > >        required = PAGES_FOR_IO + ((flags & SF_NOCOMPRESS_MODE) ? > > -- > > 1.7.1 -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html