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

From: Barry Song
Date: Sat Dec 31 2011 - 03:56:35 EST

2011/12/29 Bojan Smojver <bojan@xxxxxxxxxxxxx>:
> On Thu, 2011-12-29 at 11:20 +0800, Barry Song wrote:
>> 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.
> Interesting, thanks.

we did see some visible IO performance improvement now. the main
reason we didn't see that before is because we enable on-demand
cpufreq in default status. while saving and resuming from snapshot,
cpu frequence is switched frequently due to IO sleep and
compression/uncompression CPU consume. then we enable Performance
policy while booting, and move to on-demand after system boot, we did
see a great performance improvement.
for our inand card, the speed to read/uncompress snapshot is improved
from 7.x MB to 11MB.

> --
> Bojan
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