Why the system becomes unresponsive before system total memory be reached ?

I've 2G DDR3 installed (1802MB usable) but when memory usage reach ~1450MB the system starts to be unresponsive and stay freezing until the memory usage reduce.

% uname -r

% free -m
              total       used       free     shared    buffers     cached
Mem:          1802       1614        187        147        189        301
-/+ buffers/cache:       1123        679
Swap:         1023        206        817

To monitor memory usage I'm using a awesome wm widget.

Swap read speeds:

 % sudo hdparm -tT /dev/sda5

 Timing cached reads:   3958 MB in  2.00 seconds = 1979.41 MB/sec
 Timing buffered disk reads: 130 MB in  3.02 seconds =  43.03 MB/sec

Swap write speeds (not swap to be precise, but write speed to disk partition):

 # dd if=/dev/zero of=/dev/sda5 bs=8k count=500000
 54587+0 records in
 54587+0 records out
 447176704 bytes (447 MB) copied, 7.81582 s, 57.2 MB/s
  • Take a look at the system log. If the OOM killer is active, the system is in trouble. Otherwise, the swap is probably slow as hell. – Daniel B Jul 18 '14 at 18:54
  • Your system become slow because your swap is using 206MB. This is to be expected. – Ramhound Jul 18 '14 at 18:55
  • @DanielB I don't know how to check if OOM killer is active. I've updated question with swap partition speeds. – Victor Aurélio Jul 18 '14 at 19:24
  • @Ramhound your comment make no sense to me, since the swap resides in disk, how can this affect memory usage ? can you explain your comment please. – Victor Aurélio Jul 18 '14 at 19:25
  • Read speeds for swap are only 1 part, what are the write speeds like? – cybernard Jul 18 '14 at 19:42

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.