Hello list,
I thought I should share this experience I've just had with the latest kernel RC and cgroups (+ vserver of course).
Upgrading from 2.6.36, I saw this new option in the kernel config: "Memory Resource Controller Swap Extension enabled by default" (aka CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED). This is set to "No" as a default, so I left it that way and booted the new kernel.
The result was a kernel in which the swap controller was indeed disabled and could not be enabled by any means I could think of (cgroups were mounted with "-o all", no sysctl for that option ...). In effect, this breaks cgroups and prevents your guests from starting properly in case you have any memory.memsw limits set for them. The only solution was to build a new kernel with CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED set to "Yes".
Now perhaps there *is* a way to enable this particular subsys after boot, and if anyone can find it, I'll be glad to hear about it :-)
Cheers,
Romain Riviere
Received on Mon Feb 14 09:50:11 2011