swap space is not freed when it is no longer used

[Klaus Vormweg]

Binary package hint: linux-image-2.6.28-11-generic

Swap space is claimed, when I use memory intesive applications like VmWare or Gimp with big pictures. It seems that the used swap space is almost never freed again. That leads to an unusable slow system, when more swap space is needed and ultimatly to a kenerl panic (out of memory).

Here is a swap space statistics of today (sysstat sar -S). Swap space usage goes up after the start of VmWare (around 13:10), but does not go down again after stopping VmWare (around 13:20). The last line depicts an empty Gnome Desktop with no (visible) programs running.

              kbswpfree kbswpused %swpused kbswpcad %swpcad
10:55:01 977752 18236 1,83 840 4,61
11:05:01 977752 18236 1,83 840 4,61
11:15:01 977752 18236 1,83 840 4,61
11:25:01 977340 18648 1,87 744 3,99
11:35:01 976040 19948 2,00 600 3,01
11:45:01 969160 26828 2,69 996 3,71
11:55:01 957384 38604 3,88 1512 3,92
12:05:01 939636 56352 5,66 1752 3,11
12:15:01 928496 67492 6,78 2284 3,38
12:25:01 916812 79176 7,95 2664 3,36
12:35:01 916448 79540 7,99 3360 4,22
12:45:01 916448 79540 7,99 3360 4,22
12:55:01 916448 79540 7,99 3360 4,22
13:05:02 911376 84612 8,50 6576 7,77
13:15:03 362060 633928 63,65 35120 5,54
13:25:01 421472 574516 57,68 44104 7,68
13:35:01 423808 572180 57,45 44512 7,78
13:45:01 430692 565296 56,76 45100 7,98
13:55:01 438900 557088 55,93 48868 8,77
14:05:01 487552 508436 51,05 45376 8,92
14:15:01 493624 502364 50,44 45244 9,01

System is a P4 with 1GB ram and 1 GB swap

Ubuntu version: 9.04
Kernel: linux-image-2.6.28-11-generic 2.6.28-11.42

[Klaus Vormweg (klaus-vormweg-deactivatedaccount)]

This behaviour seems to be caused by UXA hardware acceleration of the intel xorg video driver. So this does not concern the kernel