linux-kernel - Re: [linux-pm] [PATCH] PM: HIBERNATION: skip the swap size check if the snapshot image size is anticipative

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Date:	Mon, 7 Nov 2011 09:31:10 +0800
From:	Barry Song <21cnbao@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Barry Song <Barry.Song@....com>,
	Xiangzhen Ye <Xiangzhen.Ye@....com>,
	linux-kernel@...r.kernel.org, Barry Song <Baohua.Song@....com>,
	linux-pm@...ts.linux-foundation.org,
	linux-arm-kernel@...ts.infradead.org,
	DL-SHA-WorkGroupLinux <workgroup.linux@....com>
Subject: Re: [linux-pm] [PATCH] PM: HIBERNATION: skip the swap size check if
 the snapshot image size is anticipative

2011/11/6 Barry Song <21cnbao@...il.com>:
> 2011/11/6 Pavel Machek <pavel@....cz>:
>> Hi!
>>
>>> From: Barry Song <Baohua.Song@....com>
>>>
>>> Current swsusp requires swap partitions even larger than real saved pages
>>> due to the worst compress ratio:
>>> but for an embedded system, which has limited storage space, then it might
>>> can't give the big size 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 bootloader 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.
>>
>> Would it be better to have /sys/power/... entry which would allow
>> configuring expected compression ratio at runtime?
>
> i think it is better to have a sys node than add another kernel param.
> but the point is i only care about the final image size but not
> compression ratio. i don't care how well lzo will do for me since i
> only have limited disk space and know how many pages want to be saved.
> there has been a image_size node, will we have a expected_image_size node?

or will we have just a node named /sys/power/check_size, if
1(default), check, otherwise(0 set by users), skip checking?

>>                                                                Pavel

-barry
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