linux-kernel - Re: [PATCH]: Compress hibernation image with LZO (in-kernel)

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Date:	Sat, 31 Jul 2010 11:18:57 +1000
From:	Nigel Cunningham <nigel@...onice.net>
To:	Bojan Smojver <bojan@...ursive.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH]: Compress hibernation image with LZO (in-kernel)

Hi.

On 31/07/10 11:03, Bojan Smojver wrote:
> On Sat, 2010-07-31 at 09:40 +1000, Nigel Cunningham wrote:
>
>> How about vmallocing the cmp as well? That would greatly reduce the
>> potential for page allocation failures while still letting you use an
>> order 6 area.
>
> In save_image(), that worked. In load_image() it would cause a crash
> (something about kernel not being able to satisfy paging request). So, I
> just made it __get_free_pages() instead. But, yeah good point.
>
> Keep in mind that I have absolutely no idea how kernel memory allocation
> works. I'm kinda coping and pasting code and hoping it doesn't crash :-)

It should be possible to do the allocation at that point. I might see if 
I can take a look later on.

>>> PS. I guess with this, read_sync can simply disappear as well.
>>
>> I haven't looked at the code for a while, but it might still be needed
>> for the header? I know that in TuxOnIce, I need to read the first page
>> synchronously when bootstrapping reading the image (can't read the next
>> page until you know where it is, and its location is on the first page).
>> Since swsusp uses those index pages, I think it would have the same
>> issue - they would need to be read before it could read the following
>> pages. Of course I'm going off memory :)
>
> I think it can go, because the header is already read/written with&bio
> set to NULL (sync read). See patch to remove read_sync.

Okee doke.

By the way, please inline your patches. It makes it much easier to read 
and comment on them.

Oh, and I've said it privately but not publicly: great work!

Regards,

Nigel
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