Hi,

I'm running R5E50 and am trying to configure ACPI S4 sleep. It is now possible for me to use hibernate and resume from hard drive. The only problem is that resume takes 3 to 4 minutes with 512 MB RAM no swap. I used use_suspend2.sh to enable everything.

What could cause the long resume times (3 minutes to read 512 ram image)?

I just did some more tests and it seems like read speed from IDE hard drive during resume is terrible. I found this in dmesg:

Suspend2 debugging info:
- SUSPEND core : 2.2.8.4
- Kernel Version : 2.6.18-chw-13
- Compiler vers. : 4.1
- Attempt number : 2
- Parameters : 0 16400 0 1 0 4
- Overall expected compression percentage: 0.
- SwapAllocator active.
Swap available for image: 194786 pages.
- I/O speed: Write 29 MB/s, Read 7 MB/s.
- Extra pages : 273 used/500.

Read speed when i boot normal is about 55 MB/s. When I check with hdparm on normal boot is DMA enabled, but after resume is it disabled. Im using a Gigabyte 945P-S3 motherboard with Intel 945P chipset.

Does anyone have a clue whats causing the DMA to disappear after hibernate?

Problem solved!

I re-compiled my kernel and enabled CONFIG_IDEDMA_PCI_AUTO. It turned out that I never got DMA enabled for IDE by kernel, but my hdparm.conf adjusted the settings to use DMA when system had booted normally.

By the way, I had too compile LZF support into the kernel instead of as a module which is default in R5E50 if i use lzf as a compressor otherwise decompression will fail and the kernel will panic on resume. Maybe it is a good idea to compile lzf into the kernel by default in future releases to avoid confusion when suspend2 is used?

Now I am able to suspend in about 10 seconds and resume in 30 from pressing power switch to fully up and running which I think is OK performance.

I hope this will help others that have problems with suspend2.

sounds like a cool feature for my slave backend.

I hope it is possible to do this in the future without recompiling the kernel.

I will live without for now.
Unfortunately, i often need to do fresh upgrades to fix major screw ups or fs corruption. Adding a recompile of the kernel would turn a reinstall from hours into days to get back to where i was with customizations / fixes.