VSwap testing
This article describes how to test VSwap functionality
[originally written by xemul@]
We need the following set of atomic tests
- RAM limit works
- SWAP limit works
- OOM killer works
- Pages sent to swap can be read back again
- No real swapout starts when there's enough RAM on the node
- No leaks happen after container stop
To do this the following set of atomic tests is required: 1) RAM limit works
- Start container with unlimited RAM and SWAP.
- Note the physpages.held value
- Set RAM = physpages.held + X
- Run memeater, that will map and touch RAM pages
- _Before_ memeater exits check, that physpages.held didn't grow above the .limit
2) SWAP limit works
- Start container with unlimited RAM and SWAP.
- Note the physpages.held value
- Set RAM = physpages.held + X
- Set SWAP = Y
- Run memeater, that will map and touch RAM + SWAP pages
- Check that none of physpages.held and swappages.held grew above the .limit (memeater _may_ be killed during this test)
3) OOM killer works
- Start two containers with unlimited RAM and SWAP
- Set RAM and SWAP for both like in previous examples
- Run memeater in one of them, that consumes infinite amount of RAM.
- Check, that memeater is killed in the 1st container
- Check, that no tasks in the 2nd one are killed
(the above three can probably be made of vzt-slm test) 4) Pages sent to swap can be read back again
- Start container with unlimited RAM and SWAP.
- Note the physpages.held value
- Set RAM = physpages.held + X
- Run memeater, that will map and write to 2xRAM pages
- Check, that swappages.held is not zero
- Make memeater read the whole memory again and check that the values written are preserved
5) No real swapout starts when there's enough RAM on the node
- Take a node with non-zero swap partition
- Start a container with unlimited RAM and SWAP
- Note the physpages.held value
- Check that real swap is not used
- Set RAM = physpages.held + X
- Run memeater, that will eat 2xRAM pages
- Check, that memeater is not dead
- Before memeater exits check, that swappages.held is not zero
- Check that real swap is still not used
6) No leaks happen after container stop. This will be done using kmemleak - see PSBM-34183
