On 04/14/2013 04:28 AM, Michael S. Tsirkin wrote:
On Fri, Apr 12, 2013 at 09:47:08AM -0400, Michael R. Hines wrote:
Second, as I've explained, I strongly, strongly disagree with unregistering
memory for all of the aforementioned reasons - workloads do not
operate in such a manner that they can tolerate memory to be
pulled out from underneath them at such fine-grained time scales
in the *middle* of a relocation and I will not commit to writing a solution
for a problem that doesn't exist.
Exactly same thing happens with swap, doesn't it?
You are saying workloads simply can not tolerate swap.
If you can prove (through some kind of anaylsis) that workloads
would benefit from this kind of fine-grained memory overcommit
by having cgroups swap out memory to disk underneath them
without their permission, I would happily reconsider my position.
- Michael
This has nothing to do with cgroups directly, it's just a way to
demonstrate you have a bug.
If your datacenter or your cloud or your product does not want to
tolerate page registration, then don't use RDMA!
The bottom line is: RDMA is useless without page registration. Without
it, the performance of it will be crippled. If you define that as a bug,
then so be it.
- Michael
