maemo.org - Talk - Improved LZO or ported Snappy for ZRAM?

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- - Improved LZO or ported Snappy for ZRAM? (https://talk.maemo.org/showthread.php?t=87461)

Improved LZO or ported Snappy for ZRAM?

A per this discussion 8.5+ months ago:

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I’m hoping they’ll be clever enough to back port the zram snappy compression patches at some stage

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That sounds handy/cool, what is it?

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Zram is what’s being used instead of a storage-based swap partition, and I’d suggest is why there is so much less (read none) soft blocking compared to the n900 (to be fair the much larger amount of ram helps a lot too). Instead of putting swapped out memory to a swap partition, it is instead compressed but still kept in memory. It tends to use a whole pile less space (than just being kept in ram), and means that swap operations no longer have any i/o requirement, at the cost of a little more cpu usage.

The snappy compression patches were about using the google snappy compression format (which is more efficient that the LZO algorithm that zram uses) to improve zram performance.
Unfortunately, I since realised that it’s quite x86_64 specific so it’s considered unlikely to be of much benefit on arm :-(
There is apparently though some recent improvements to the LZO algorithm that improve it’s performance greatly which would be great to see adopted on the n9 :-)

I was wondering if anyone knows whether the improvements to LZO did come with PR1.2 or PR1.3?
If not, perhaps it's possible to merge them ourselves?
Or perhaps it is in-fact feasible to back-port Snappy compression patches?

Cheers.

Re: Improved LZO or ported Snappy for ZRAM?

I'm not sure of that but you may want to check this out by rainisto which uses the spare mtd block for swap instead of taking away 256MB of RAM as swap and keeping RAM at 1GB...

Re: Improved LZO or ported Snappy for ZRAM?

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Originally Posted by thedead1440 (Post 1282529)

I'm not sure of that but you may want to check this out by rainisto which uses the spare mtd block for swap instead of taking away 256MB of RAM as swap and keeping RAM at 1GB...

Geez that was quick....
Seems you're always the one addressing my posts lately, step away from the forum, it can become highly addictive, I know from experience :D
Yeah I have that thread bookmarked, I hadn't read it all the way through yet though, so thanks for pointing to that post, very interesting & definitely something I'll try eventually.
But I was more interested in whether anyone knows more about what I've asked...

Cheers.

Re: Improved LZO or ported Snappy for ZRAM?

If you want to build a kernel and benchmark, the tiny patches are available here.

Re: Improved LZO or ported Snappy for ZRAM?

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Originally Posted by Hurrian (Post 1282761)

If you want to build a kernel and benchmark, the tiny patches are available here.

Nice find, looks like a perfect addition for the kernel update project:
https://wiki.merproject.org/wiki/N9_...update_project

I wonder if using the Snappy algorithms instead is feasible...
I believe they're only x86_64 specific ATM, although admittedly I haven't investigated closely yet.