On a fresh started system, free reports about 1.5G used RAM (8G RAM alltogether, Ubuntu 12.04 with lightdm and plasma desktop, one konsole window started). Having the apps running I use, it still consumes not more than 2G. However, having the system running for a couple of days, more and more of my free RAM disappears -- without showing up in the list of used apps: while smem --pie=name reports less than 20% used (and 80% being available), everything else says differently. free -m for example reports on about day 7:
total used free shared buffers cached
Mem: 7459 7013 446 0 178 997
-/+ buffers/cache: 5836 1623
Swap: 9536 296 9240
(so you can see, it's not the buffers or the cache). Today this finally ended with the system crashing completely: the windows manager being gone, apps "hanging in the air" (frameless) -- and a popup notifying me about "too many open files". Syslog reports:
kernel: [856738.020829] VFS: file-max limit 752838 reached
So I closed those applications I was able to close, and killed X using Ctrl-Alt-backspace. X tried to come up again after that with failsafeX, but was unable to do so as it could no longer detect its configuration. So I switched to a console using Ctrl-Alt-F2, captured all information I could think of (vmstat, free, smem, proc/meminfo, lsof, ps aux), and finally rebooted. X again came up with failsafeX; this time I told it to "recover from my backed-up configuration", then switched to a console and successfully used startx to bring up the graphical environment.
I have no real clue to what is causing this issue -- though it must have to do either with X itself, or with some user processes running on X -- as after killing X, free -m output looked like this:
total used free shared buffers cached
Mem: 7459 2677 4781 0 62 419
-/+ buffers/cache: 2195 5263
Swap: 9536 59 9477
(~3.5GB being freed) -- to compare with the output after a fresh start:
total used free shared buffers cached
Mem: 7459 1483 5975 0 63 730
-/+ buffers/cache: 689 6769
Swap: 9536 0 9536
Two more helpful outputs are provided by memstat -u. Shortly before the crash:
User Count Swap USS PSS RSS
mail 1 0 200 207 616
whoopsie 1 764 740 817 2300
colord 1 3200 836 894 2156
root 62 70404 352996 382260 569920
izzy 80 177508 1465416 1519266 1851840
After having X killed:
User Count Swap USS PSS RSS
mail 1 0 184 188 356
izzy 1 1400 708 739 1080
whoopsie 1 848 668 826 1772
colord 1 3204 804 888 1728
root 62 54876 131708 149950 267860
And after a restart, back in X:
User Count Swap USS PSS RSS
mail 1 0 212 217 628
whoopsie 1 0 1536 1880 5096
colord 1 0 3740 4217 7936
root 54 0 148668 180911 345132
izzy 47 0 370928 437562 915056
Edit: Just added two graphs from my monitoring system. Interesting to see: everytime when there's a "jump" in memory consumption, CPU peaks as well. Just found this right now -- and it reminds me of another indicator pointing to X itself: Often when returning to my machine and unlocking the screen, I found something doing heavvy work on my CPU. Checking with top, it always turned out to be /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch -background none.
So after this long explanation, finally my questions:
- What could be the possible causes?
- How can I better identify involved processes/applications?
- What steps could be taken to avoid this behaviour -- short from rebooting the machine all X days?
I was running 8.04 (Hardy) for about 5 years on my old machine, never having experienced the like (always more than 100 days uptime, before rebooting for e.g. kernel updates). This now is a complete new machine with a fresh install of 12.04. In case it matters, some specs:
AMD A4-3400 APU with Radeon(tm) HD Graphics, using the open-source ati/radeon driver (so no fglrx installed), 8GB RAM, WDC WD1002FAEX-0 hdd (1TB), Asus F1A75-V Evo mainboard. Ubuntu 12.04 64-bit with KDE4/Plasma. Apps usually open more or less permanently include Evolution, Firefox, konsole (with Midnight Commander running inside, about 4 tabs), and LibreOffice -- plus occasionally Calibre, Gimp and Moneyplex (banking software I'm already using for almost 20 years now, in a version which did fine on Hardy).
Edit:
Today I found one of the "evil guys": KDE4s plasma-desktop. Used memory was again up to 5GB, when I did a killall plasma-desktop && plasma-desktop. This freed up 1.3GB RAM! ps says:
RSS SIZE VSZ
plasma usage before restart 120988 526472 1300816
plasma usage after restart 92352 495972 1263632
So where have those 1.3GB been? The diff between those values, if added up, amount to 96MB -- not 1.3GB.
And this can only be one part, as still 3.7GB are in use (should be less than 2GB). I monitored this during the past 6 days using several tools: used memory (not talking about cache and buffers) increases slowly but steadily. Even if I'm not at my desk to run anything...
As to monitoring processes with open files, I currently use the following 1-liner (I love shell and especially bash) to get the top-5:
echo "$(for pid in $(ls -a /proc|egrep '^([0-9])*$'|sort -n 2>/dev/null); do
if [ -e /proc/$pid/fd ]; then FHC=$(ls -l /proc/$pid/fd|wc -l);
if [ $FHC -gt 0 ]; then PNAME="$(cat /proc/$pid/comm)";
echo "$FHC files opened by $pid ($PNAME)"; fi; fi; done)"|sort -r -n|head -n5
Command here in 4 lines for better readability. Nothing much yet from there -- except that Skype doesn't like have the Internet connection broken. Each disconnect causes a slight increase of its open files, but nothing dramatic. On the other hand it seems like plasma is also responsible for that:
See the drop of file handles at the end? That was the plasma restart.
