new disk layout

[Bill Davidsen]

Roberto Ragusa wrote:
> Bill Davidsen wrote:
> 
>> In suspend to disk, see the output of the 'free' command. The data in
>> the 'buffers' and 'cached' need not be saved, the buffers are written to
>> the filesystem and the cached data are discarded. So the room you really
>> need is the swap in use plus the memory in use. And it gets more complex
>> than that, because the memory is compressed as it's written out (more
>> for speed than size, in practice),
> 
> Everything correct.
> The decision to not save buffers and cached is debatable. Even if
> it is memory which can be read again from the disk, it is MUCH
> faster to read from the swap image in a contiguous fashion, than
> to seek everywhere for minutes after a suspend.

That argument makes no sense for buffers, you don't want to compress them, write 
them to swap, read them in, decompress them, all so you can then write them to 
the filesystem anyway.

> That is one of the really good things which only tuxonice has.

I hope you're remembering that wrong, if it's going to be written to disk 
there's no benefit to doing a lot now so you can slow the restore and then do 
all that i/o anyway. You can make the argument for cache, at least you might 
save so i/o after resume.

> I hope to see it finally merged.

Don't hold your breath, for years I kept pointing out issue with suspend and 
being told "stop whining and send patches," and I would say "the patch is 
suspend2." It's been renamed, but still mostly not merged, and new bugs have 
been added.
> 
>> so it's really hard to guess how much
>> swap will actually be used.
> 
> But it is really simple to decide the size of the swap
> partition: use a big one.
> There is really no disadvantage to have a bigger one.
> 
> 2 GB RAM? -> 5 GB swap
> 
> more than enough to have 1gb swap used and suspend everything;
> probably large enough even when you upgrade to 4 GB RAM.
> 
> I don't think anyone really cares about 2 or 3 GB of disk
> on a modern machine (having 2 GB of RAM makes it modern).
> 
Haven't done much embedded work? Think 512M RAM, 2GB non-volatile storage, maybe 
another bit of EAPROM for firmware. That's not Fedora, but it definitely is 
suspend/resume.

-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot