Re: zram on ARM

[Luigi Semenzato <semenzato@google.com>]

Some parts of my previous message are premature---I haven't actually
tried exactly this code on x86, and I should also try David Rientjes's
patch.  But I'd still like to know how this has been tested on ARM.

Thanks!

On Fri, Nov 2, 2012 at 12:59 PM, Luigi Semenzato <semenzato@google.com> wrote:
> Does anybody have any information on the status of zram on ARM?
> Specifically, how much it has been tested.
>
> I noticed that zram and zsmalloc on ToT no longer have the x86
> restriction, and they compile fine on our 3.4 branch.  Sadly, that's
> where my luck ends.
>
> When I run my standard Chrome load (which just opens a bunch of
> memory-intensive browser tabs), Chrome dies shortly after the system
> starts swapping pages out.  For instance, here's are the SI and SO
> fields of "vmstat 1":
>
>    si   so
>     0    0
>     0    0
>     0    0
>     0    0
>     0    0
>     0    0
>     0    0
>     0    0
>     0  168
>     0    0
>     0  924
>   188 26332
>   520 30672
>  1304 32208
>  2360 30804
>  18836 24832
>                      <--- chrome dies here
>  6496    0
>   892    0
>   260    0
>     8    0
>
> I also have a simpler load: a program that allocates memory non-stop,
> and fills part of it with data from /dev/urandom (to simulate the
> observed compressibility). The program never reads its data though, so
> it doesn't get swapped back in, as in the previous load.  This runs
> for a while and partially fills the swap device, then the system
> hangs.
>
> Deja vu, eh?  I am running this with my patch, which may result in
> extra OOM kills.  Interestingly, a few threads are blocked in
> exit_mm(), but not on a page fault.  Most processes are in
> congestion_wait(), so this is probably not the same situation I was
> seeing earlier.
>
> Anyway, I am attaching the output of SysRQ-X with lots of stack
> traces.  Thank you very much for any information!
>
> Luigi

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