On Sat, Feb 02, 2008 at 09:14:57PM -0600, Jack Steiner wrote: > Also, most (but not all) applications that use the GRU do not usually do > anything that requires frequent flushing (fortunately). The GRU is intended > for HPC-like applications. These don't usually do frequent map/unmap > operations or anything else that requires a lot of flushes. > > I expect that KVM is a lot different.
I don't think so. invalidate_page/pages/range_start,end is a slow and unfrequent path for KVM (or alternatively the ranges are very small in which case _range_start/end won't payoff compared to _pages). Whenever invalidate_page[s] become a fast path, we're generally I/O bound. get_user_pages is always the fast path instead. I thought it was much more important that get_user_pages scale as well as it does now and that the KVM page fault isn't serialized with a mutex, than whatever invalidate side optimization. get_user_pages may run frequently from all vcpus even if there are no invalidates and no memory pressure and I don't mean only during startup. > I have most of the GRU code working with the latest mmuops patch. I still > have a list of loose ends that I'll get to next week. The most important is > the exact handling of the range invalidates. The code that I currently have > works (mostly) but has a few endcases that will cause problems. Once I > finish, I'll be glad to send you snippets of the code (or all of it) if you > would like to take a look. Sure. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
