On Tue, Jul 21, 2015 at 12:08:40PM +0300, Nikolay Borisov wrote: > On 07/21/2015 10:48 AM, Michal Hocko wrote: > > On Mon 20-07-15 14:22:32, Nikolay Borisov wrote: > >> What about memsw.limit_in_bytes - memory.limit_in_bytes for the total swap > > > > No this is not how the swap extension works. memsw counter covers > > usage+swap. You can have up to memsw.limit_in_bytes swapped out. So > > I think you are wrong with that assumption. According to the > documentation here: > https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/sec-memory.html > (the box titled "Setting the memory.memsw.limit_in_bytes and > memory.limit_in_bytes parameters") it seems that the space that could be > swapped is actually memsw.limit_in_bytes - memory.limit_in_bytes. > > The way I understand is you will only start swapping after the limit in > memory.limit_in_bytes has been exhausted and you will be able to swap > only until memsw.limit_in_bytes is exhausted (but since > memory.usage_in_bytes is already calculated in, which would equal to > memory.limit_in_bytes in a memory pressure situation) you effectively > have memsw.limit_in_bytes - memory.limit_in_bytes, no? No, the cgroup can also swap due to global/parental memory pressure, not just due to memory.limit_in_bytes. In that case, it can get its pages swapped out until it reaches memsw.limit_in_bytes, with memory consumption well below memory.limit or even 0. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
