Set_disksize_zram_LTP_testsuite

Set_disksize_zram_LTP_testsuite

[Na Nha]

My name is Le Minh nhan, I am a Linux developer.

When I had used LTP testsuite to test our kernel, I encountered an error.
Testcase "zram02" of LTP testsuite  sets 100G disksize to zram, the
kernel says "cannot allocate memory". But there is no problem if I use
other values: 10G,20G...90G to set disksize of zram.

Could you please help me to find what the problem is?
What is the limitation of disksize I can set to zram or any suggestion
I could do?

I am so happy and grateful if you repsond my email.

Thanks and best regards,

Le Minh Nhan

Re: Set_disksize_zram_LTP_testsuite

[Karel Zak]

On Mon, Oct 23, 2017 at 11:48:25PM +0700, Na Nha wrote:
> My name is Le Minh nhan, I am a Linux developer.
> 
> When I had used LTP testsuite to test our kernel, I encountered an error.
> Testcase "zram02" of LTP testsuite  sets 100G disksize to zram, the
> kernel says "cannot allocate memory". But there is no problem if I use
> other values: 10G,20G...90G to set disksize of zram.

The command zramctl uses 64-bit numbers for sizes, so it's without any
limitation, but don't forget that kernel uses RAM to allocate it...
see

 https://www.kernel.org/doc/Documentation/blockdev/zram.txt

where is more details about the limits, some of the limits is possible
set by /sys.

Note that zramctl --size modifies disksize attribute only.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com