Re: Suspend 2 merge

Christoph Hellwig
2004-11-27T04:18:45Z

On Fri, Nov 26, 2004 at 01:38:48PM +0100, Pavel Machek wrote:
> > Again, when you're running on limited time, twice as fast is still twice
> > as fast.
>
> My machine suspends in 7 seconds, and that's swsusp1. According to
> your numbers, suspend2 should suspend it in 1 second and LZE
> compressed should be .5 second.
>
> I'd say "who cares". 7 seconds seems like fast enough for me. And I'm
> *not* going to add 2000 lines of code for 500msec speedup during
> suspend.

Yupp. Premature optimization is the roo of all evil. swsusp is

a) an absolute slowpath compared to any normal kernel operation,
and called extremly seldomly
b) only usefull for a small subset of all linux instances

hacking core code (fastpathes) for speedups there is a really bad idea.
If you can speed it up without beeing intrusive all power to you.

> > I'm trying not to make assumptions about how we're writing the image,
> > either. If you want to pipe your image over a network to some server,
> > you should be able to, and not have to implement compression again in
> > the writer for that.
>
> Suspend-over-network is obscure-enough
> feature. Compressed-suspend-over-network is even worse.
>
> BTW my feeling is that if you want to do suspend-over-network, you
> should just modify nbd to work with suspend2 and stop adding
> special-purpose code to suspend.

Honestly I think it's a feature so obscure that we wouldn't ever want to
merge it unless it just happens to work as a fallout of a more important
feature.