Re: 2.6.10-rc3: kswapd eats CPU on start of memory-eating task

[Nick Piggin <nickpiggin@yahoo.com.au>]

Mikhail Ramendik wrote:
> Hello,
> 
> With kernel 2.6.10-rc3 and 256 M RAM, when I start a task taht eats a ot of 
> RAM (for example, viewing a big TIFF file; also tested with a synthetic 
> "eater"), in the resulting swapping process kswapd tahes quite a bit of CPU 
> time. The computer becomes extremely unresponsive, the clock (in icewm) stops 
> for periods of time up to a minute). And the task startup itself is somewhaat 
> slow.
> 
> I have checked both 2.6.8.1 and 2.6.9 for comparison, and they fare a lot 
> better. The CPU hogging is not there, the computer is much more responsive, 
> and the task starts faster.
> 

Hi Mikhail,

I'm not quite sure what the problem would be. Please check that you are using
the same config for each kernel, and both kernels have detected the same amount
of memory.

Then, can you start by posting /proc/vmstat before and after running the
synthetic "eater" for some amount of time, with both 2.6.9 and 2.6.10-rc3; so:

boot 2.6.9
cat /proc/vmstat > 2.6.9-pre ; ./eater ; cat /proc/vmstat 2.6.9-post

and the same for 2.6.10-rc3.

Also, /proc/meminfo and /proc/slabinfo output for each kernel before running
eater may give some clues.

Oh, and can you post the source code for the "eater" as well, please?

Thanks,
Nick