21 Mar
2011
21 Mar
'11
20:53
On Mon, 21 Mar 2011 18:53:45 +0100 Jan Karawrote: > Hello, > > On Mon 21-03-11 15:02:22, Stefan Seyfried wrote: > > I have seen the following repeatedly, from time to time during the last > > years, but only today I have probably found a way to trigger it: > > > > * create some heavy FS workload on XFS, probably pushing the machine > > heavily into swap > > * stop the workload (probably that "make -j" in a big C++ project is not > > such a good idea after all...) > > * machine stays slow, as if it had no memory, starts swapping even though > > there are apparently gigabytes of free memory > > * free shows there is lots of memory free: > > susi:~ # free > > total used free shared buffers cached > > Mem: 3949728 3583132 366596 0 348 199180 > > -/+ buffers/cache: 3383604 566124 > > Swap: 2093052 317460 1775592 > Well, 366 MB free isn't that much given you have 317 MB in swap and 3.9 > GB of memory. Yes, I actually switched "used" and "free" in my mind X-). Anyway, there is no process using the memory, If I add all up, I have something like 300MB used, and I think the slabtop clearly shows that the kernel grabbed all memory. > > * swapoff often fails, even though there should be enough memory according > > to "free" > > * slabtop shows there is quite some amount of space in use: > > Active / Total Objects (% used) : 160024 / 14304077 (1.1%) > > Active / Total Slabs (% used) : 11111 / 778760 (1.4%) > > Active / Total Caches (% used) : 117 / 220 (53.2%) > > Active / Total Size (% used) : 104352.71K / 3073816.64K (3.4%) > > Minimum / Average / Maximum Object : 0.02K / 0.21K / 4096.00K > > > > OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME > > 13434482 0 0% 0.20K 707078 19 2828312K xfs_btree_cur > > 507270 0 0% 0.39K 50727 10 202908K xfs_efi_item > > 167297 8 0% 0.22K 9841 17 39364K xfs_buf_item > > 24752 21011 84% 0.03K 221 112 884K size-32 > Hmm, so you have about 3 GB of memory in unused slabs. That's indeed a > bug. This reminds me of one swap-over-NFS bug which was causing a similar > effect for journal_handle slab. And after some digging - it was bug 554081 > - I see that openSUSE 11.4 and master branches don't have the fix. Nick > forgot to commit the fix to master branch and I didn't realize that > either. So I'd bet on this patch... I'm also going to push it to master > branch. Thanks. Unfortunately it's not easy to reproduce, so I cannot instantly tell you if it's fixed. Is it possible that the same bug is / was in 11.2 or 11.3? Just because I'm pretty sure that I saw similar things on my server at home quite some time ago. The box is now 11.3, but I'm pretty sure it was 11.2 or 11.1 when I first saw it (about 1,5 years ago) Maybe we should drop all those enterprise patches from openSUSE. Makes life easier by getting closer to mainline and only the paying customers suffer :-) Lucky me that I did *not* report this on lkml or fsdevel :-) -- Stefan Seyfried "Dispatch war rocket Ajax to bring back his body!" -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-kernel+help@opensuse.org