On Tue, Jun 10, 2014 at 01:12:04PM +0200, Paolo Bonzini wrote: > Il 10/06/2014 11:59, Michael S. Tsirkin ha scritto: > >> >What's the point compared to memory-backend-ram? > >> > >> That you can use shared memory, for example together with vhost-user. > > > >I don't think it's a good idea until THP supports shared memory. > > Why? For example it would be useful for testing on machines that you don't > have root for, and that do not have a hugetlbfs mount point. For example > you could run the test case from the vhost-user's patches.
Sounds useful, I guess we could allow this when running under qtest. > THP is not a magic wand and you can get slowness from memory fragmentation > at any time. Right but there's a difference between "can get slowness when memory is overcommitted" and "will get slowness even on a mostly idle box". > We should not limit ourselves due to kernel bugs. > > Paolo Why not? Practically people do have to run this on some kernel, we should not use kernel in a way that it can't support well. Old firefox doing a ton of fsync commands and slowing the box to a crawl comes to mind as another example of this. -- MST
