[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH RFC 07/20] migration: defer precopy policy to libxl
Wei Liu writes ("Re: [PATCH RFC 07/20] migration: defer precopy policy to libxl"): > On Thu, Mar 30, 2017 at 01:19:41AM -0400, Joshua Otto wrote: > > Is the memcpy() really significant here? If this were a tight > > loop, sure, but every invocation of the policy callback implies > > both a 4MB network transfer _and_ a synchronous RPC. > > Ian, How can Joshua pass a pointer across RPC boundary to avoid excessive > copying? You can't pass a pointer across the IPC boundary. The two bits of code run in different processes, with different address spaces. Also, this precopy stats struct is tiny: two unsigned and a long. Josuha is entirely right to ask whether the overhead is significant. I think it isn't. If the performance of the proposed arrangements is inadequate, the whole design needs reconsideration - the synchronous callback is more of a concer, as Joshua suggests. But I assume it's not, or Joshua would have noticed ! Thanks, Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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