Re: [PATCH] PM / Hibernate: Improve performance of LZO/plainhibernation, checksum image

From: Barry Song
Date: Wed Dec 28 2011 - 22:20:39 EST

2011/12/29 Bojan Smojver <bojan@xxxxxxxxxxxxx>:
> On Thu, 2011-12-29 at 10:37 +0800, Barry Song wrote:
>> i mean we can load image and decompress them in different threads when
>> we reboot from hibernation. after i read codes more carefully, that
>> has actually been done by lzo_decompress_threadfn().
> Correct. Both hibernation and thaw are multi-threaded.
>> here the problem is we didn't seem to get any faster after applying
>> your compression patch when doing hibernation on SD/NAND.
>> we are trying to figure out the reason.
> This may depend on many factors:
> - how much CPU power you have
> - how many CPUs you have
> - how much I/O can your disk do
> Remember, there is one thread that does CRC32 as well and other threads
> will have to sync with that thread.
> Anyhow, it would be interesting to know where the bottleneck is on your
> particular system. If you system has lots of CPU power and fast I/O, the
> patch indeed may not do anything at all.
> PS. I did my testing on a ThinkPad T510 laptop. It has a Core i5 M520
> 2.4 GHz mobile CPU (this appears to the system as 4 CPUs - it's two
> physical cores with hyper-threading enabled). The disk is classic
> platter based disk (Seagate ST9500420AS). There is 8 GB of RAM on this
> system.

well. our guys are still debugging.
the platform is ARM cortex-a9 single-core 1Ghz SoC and we save image
to a SD card or NAND.
a phenomenon we saw is that multi-BIOs is not merged into a request by
block level elevator. so the SD/NANDdisk driver handles many small
request one page by one page.

> --
> Bojan
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at