Re: swap storm since kernel 3.2.x

From: Johannes Stezenbach
Date: Wed Feb 08 2012 - 06:52:52 EST


On Wed, Feb 08, 2012 at 09:56:15AM +0100, Toralf Förster wrote:
>
> From what I can tell is this:
> If the system is under heavy I/O load and hasn't too much free RAM (git pull,
> svn update and RAM consuming BOINC applications) then kernel 3.0.20 handle
> this somehow while 3.2.x run into a swap storm like.

FWIW, I also saw heavy swapping with 3.2.2 with the
CONFIG_DEBUG_OBJECTS issue reported here:
http://lkml.org/lkml/2012/1/30/227

But the thing is that even though SUnreclaim was
huge there was still 1G MemFree and it swapped heavily
on idle system when just switching between e.g. Firefox and gvim.

Today I'm running 3.2.4 with CONFIG_DEBUG_OBJECTS disabled
(but otherwise the same config) and it doesn't swap even
after a fair amount of I/O:

MemTotal: 3940088 kB
MemFree: 1024920 kB
Buffers: 293328 kB
Cached: 447796 kB
SwapCached: 24 kB
Active: 847136 kB
Inactive: 567200 kB
Active(anon): 478736 kB
Inactive(anon): 246744 kB
Active(file): 368400 kB
Inactive(file): 320456 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 3903484 kB
SwapFree: 3903196 kB
Dirty: 16 kB
Writeback: 0 kB
AnonPages: 673192 kB
Mapped: 40956 kB
Shmem: 52268 kB
Slab: 1434188 kB
SReclaimable: 1367388 kB
SUnreclaim: 66800 kB
KernelStack: 1600 kB
PageTables: 4880 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 5873528 kB
Committed_AS: 1744916 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 348116 kB
VmallocChunk: 34359362739 kB
DirectMap4k: 12288 kB
DirectMap2M: 4098048 kB

OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
586182 353006 60% 1.74K 32595 18 1043040K ext3_inode_cache
289062 170979 59% 0.58K 10706 27 171296K dentry
247266 107729 43% 0.42K 13737 18 109896K buffer_head


Johannes
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