Re: -nice tree [was Re: [Swsusp-devel] Re: swsusp problems [was Re: Your opinion on the merge?]]

From: Michael Frank
Date: Fri Mar 26 2004 - 01:06:57 EST

On Thu, 25 Mar 2004 23:27:45 +0100, Pavel Machek <pavel@xxxxxxx> wrote:


By the way, here's an example where having the /proc interface is a good
thing: which do you use? zip compression, lzf compression or no
compression? Until recently I always used lzf compression. I just

We should select one, and drop the others.

gzip is useless for almost everyone -> gets little testing -> is
probably broken.

upgraded my laptop's hard drive, and found I wasn't getting the
performance improvements in suspending I expected. It turns out that the
CPU is now the limiting factor. Because I had the /proc interface, I
could easily adjust the debug settings to show me throughput and then
try a couple of suspend cycles with compression enabled and with it
disabled. Without the /proc interface, I would have had to have
recompiled the kernel to switch settings. (I didn't try gzip because I
knew it wasn't going to be a contender for me).

/proc is needed a lot

- enable escape
- select reboot mode
which is essential for multibooting. We use it all the time to
boot various installations of Linux
- select compression none, lzw or gzip
none is used when disk faster that cpu-limited lzf
lzf is used when cpu is fast enough to compress to disk
Fast CPU can do 100MB/s+ to 50MB/s drives
gzip is used by some who care about image size eg flash users
- keep image mode (when compiled in)
which is used for embedded kiosks for example
Boeing requested and uses it
- default console level
Controls console messages or nice display
- access debug info header
This is needed to analyze swsusp2 performance
- access resume parameters
Saves a reboot when changing parameters
- activate
swsusp2 activation independent of apci, apm
- last result
info on why swsusp2 did not suspend such as out of
memory or swap or freezing failure
- access version info
could be dropped in mainline
- access interface version info
could be dropped in mainline


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