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

From: Nigel Cunningham
Date: Fri Jul 30 2010 - 19:40:30 EST

Hi again.

On 31/07/10 09:22, Bojan Smojver wrote:
On Sat, 2010-07-31 at 08:05 +1000, Nigel Cunningham wrote:
Is an order 6 allocation really necessary,

I tried with 5 and 4 and got slightly lower throughput numbers. With 6,
I was getting 145 to 150 MB/s, with 4 I'm getting around 130 MB/s (this
is all on hibernate).

So, here is one with 4.

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.

I might try this for TuxOnIce too - I'm only using order 0 allocations at the moment and have been wondering how I can get the higher write speed I think should be possible on my system :) I was thinking along the lines of locking, but perhaps that was the wrong area to pursue! :)

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 :)

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