Re: Gkrellm reports memory and ramdisk as disk writing

On 2015-12-21 Usama Akkad wrote:
> To reproduce:
> 
> 1. Setup your browser cache on ramdisk or disable disk cache (firefox
> way) 2. Visit any live stream or youtube video website
> 3. Gkrellm reported sda disk activity will be the same as using the
> hard disk. tools like iotop show a noticeable difference  

I tried, but my workstation has too many daemons running and the IO is
always all over the place, so it's impossible for me to tell if there's
any difference when playing a video (I couldn't see any).

Perhaps someone else on a more quiescent system can test for you.

Here's an idea: perhaps when you're switching to a dynamic ram disk or
tmpfs "disk" what is happening is instead of going out to sda to your
fs, it's going out to sda to your swap space.  If your RAM was
pressured (getting full-ish) then a tmpfs can (I think) start writing
out to swap.  If your swap was also on sda then that would be your
mystery sda activity in gkrellm.

You can test this theory by turning off swap:  swapoff -a
And retesting.

You could also see if the browser is obeying your cache tweaks.  Try
this:
touch /tmp/t
** start test **
find ~/.cache/mozilla/firefox -newer /tmp/t
** repeat the find as the test plays

If files are really being written to disk, they'll show up there.
Change the dir to match whatever your browser uses (you may have to
poke around a bit), or just use firefox.

One of these should reveal that the apparent mismatch is actually
caused by something other than gkrellm.  Good luck!