Timeline for Discrepancy between reported used memory and sum of application memory usage
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 8, 2013 at 12:43 | comment | added | Alicja Kario | I started with the applications down: there wasn't any application that was using significantly more memory after week of uptime than when it was freshly started, that's why I started searching what's happening in the kernel | |
| Mar 5, 2013 at 22:35 | comment | added | Huygens | You know, it is the top-down or bottom-up approach. You want one where you start form the kernel detailed info and go up to the app, I would start from the apps and try identifying which is the culprit. Both approach are correct! But I can only help you when drilling from the apps to the kernel I'm afraid, as we have hit the limit of my kernel knowledge now... | |
| Mar 5, 2013 at 17:16 | comment | added | Alicja Kario | @Hyugens: There's 525048 kB of memory that I don't know how it's used, it's not SLAB, it's not cache, it's not buffers and it's not user applications. The question is, how can I get detailed info about kernel memory usage? | |
| Mar 3, 2013 at 21:31 | comment | added | Huygens | Is your question just about the counting of memory? Or are you looking for which process is using the memory? I am not sure how to help you further. | |
| Mar 3, 2013 at 21:06 | comment | added | Alicja Kario | I appreciate your input, but as I've said, disabling zram and enabling regular swap didn't help, ergo zram isn't the problem. | |
| Mar 3, 2013 at 18:45 | comment | added | Huygens | @HubertKario as you know I have set up a test VM for zram. I have found out that under memory stress, the kernel will start swaping, and instead of having a linear filling up of the swap it was much faster/easy to do so! After removing some of the memory pressure I still had swap > free memory, so the kernel had to keep some swap. I reactivated my hard disk swap and removed zram. This force the memory of the 4 zram disks to be put back in RAM and at the end I ended up with: 0 MB swap used and 1 GB free memory!! zram can be handy but also a memory hog! | |
| Mar 3, 2013 at 8:24 | comment | added | Huygens | @HubertKario Neither the kernel documentation on zram nor the compcache (the original project) are telling/advising to any hard disk swap. I guess this would depend on the workload and resource need that it implies. On Linux you can give priority for each swap, like I said I have one machine which is using zram, it has the highest priority for zram swap, and the lowest for hard disk swap, and I can clearly see one filling up before the other is even touched. An example of how to configure it: wiki.archlinux.org/index.php/Swap#Priority | |
| Mar 3, 2013 at 8:15 | comment | added | Huygens | I do have an old PC which I am still using regularly with only 1 GB of RAM, an old Sempron 2800+ and an AGP Radeon card. Memory is extremely limited nowadays, by simply browsing the internet you quickly start using the swap. On this machine, I have set up zram, but I also kept my swap partition. I could not give too much of the 1 GB to zram without limiting my physical RAM, so I gave only 256 MB, Basically it was like increasing the RAM from 1 GB to something a bit higher (with a little overhead ;-) ) and that was just enough for my usage, but I still keep on swaping to disk! | |
| Mar 2, 2013 at 19:55 | comment | added | Alicja Kario | First: while your in-depth explanation of zram is not far from reality, it's supposed to be used without real swap. Second: disabling zram didn't really help. The problem is probably caused by some bug in radeon driver, unfortunately I won't have time to debug it in near future. | |
| Mar 1, 2013 at 22:51 | history | answered | Huygens | CC BY-SA 3.0 |