From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753952Ab1KYKVu (ORCPT ); Fri, 25 Nov 2011 05:21:50 -0500 Received: from co202.xi-lite.net ([149.6.83.202]:40919 "EHLO co202.xi-lite.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752789Ab1KYKVs (ORCPT ); Fri, 25 Nov 2011 05:21:48 -0500 Message-ID: <4ECF6C36.8000702@parrot.com> Date: Fri, 25 Nov 2011 11:21:42 +0100 From: Matthieu CASTET User-Agent: Thunderbird 2.0.0.24 (X11/20100228) MIME-Version: 1.0 To: Barry Song CC: "pavel@ucw.cz" , "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 References: <1322208422-12346-1-git-send-email-Barry.Song@csr.com> In-Reply-To: <1322208422-12346-1-git-send-email-Barry.Song@csr.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, but did embedded system will really use swap interface ? Often they don't have swap and can already save suspend image in disk/nand : - SNAPSHOT_CREATE_IMAGE - read it from /dev/snapshot and write it to a file. The only problem with the current interface, is that you can't SNAPSHOT_UNFREEZE before reading the image. But this is need for some filesystem that have thread. For example we have a demo where we save the suspend image in a ubi volume and restore it from bootloader. Matthieu Barry Song a écrit : > 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) ?