Shridhar Daithankar wrote:Linux doesn't release the swap file page when a page is read back: If a page is only read by the user space app, then the swapped out page remains valid, and thus the kernel can skip the write to disk on the next swapout. Thus if you are paranoid, you must limit the total address space to the size of your swap files.
Hi all,
Following is from Documentation/vm/overcommit-accounting
-------------
2 - (NEW) strict overcommit. The total address space commit
for the system is not permitted to exceed swap + a
configurable percentage (default is 50) of physical RAM.
Depending on the percentage you use, in most situations
this means a process will not be killed while accessing
pages but will receive errors on memory allocation as
appropriate.
It is strange to choose 50% of RAM plus swap (what if your spam is
small). I thought it would be 100% of RAM plus the swap that exceeds RAM
size.
If your swap space (your wrote "spam" - I assume a typo) is small, then you'll run into problems. It's recommended that your swap space should be 2*physical memory. I assume that many oom killer reports are from system with too small swap files, and then an updatedb run pushes the system into oom.
-- Manfred
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