On Wed, Feb 15, 2017 at 05:37:22PM +0530, Anshuman Khandual wrote: > This four patches define CDM node with HugeTLB & Buddy allocation > isolation. Please refer to the last RFC posting mentioned here for more Always include the background with the changelog itself. Do not assume that people are willing to trawl through a load of past postings to assemble the picture. I'm only taking a brief look because of the page allocator impact but it does not appear that previous feedback was addressed. In itself, the series does very little and as Vlastimil already pointed out, it's not a good idea to try merge piecemeal when people could not agree on the big picture (I didn't dig into it). The only reason I'm commenting at all is to say that I am extremely opposed to the changes made to the page allocator paths that are specific to CDM. It's been continual significant effort to keep the cost there down and this is a mess of special cases for CDM. The changes to hugetlb to identify "memory that is not really memory" with special casing is also quite horrible. It's completely unclear that even if one was to assume that CDM memory should be expressed as nodes why such systems do not isolate all processes from CDM nodes by default and then allow access via memory policies or cpusets instead of special casing the page allocator fast path. It's also completely unclear what happens if a device should then access the CDM and how that should be synchronised with the core, if that is even possible. It's also unclear if this is even usable by an application in userspace at this point in time. If it is and the special casing is needed then the regions should be isolated from early mem allocations in the arch layer that is CDM aware, initialised late, and then setup userspace to isolate all but privileged applications from the CDM nodes. Do not litter the core with is_cdm_whatever checks. At best this is incomplete because it does not look as if it could be used by anything properly and the fast path alterations are horrible even if it could be used. As it is, it should not be merged in my opinion. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
