From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Date: Fri, 15 Jul 2005 22:37:57 +0000 Subject: Re: [NUMA] Display and modify the memory policy of a process through /proc//numa_policy Message-Id: <20050715223756.GL15783@wotan.suse.de> List-Id: References: <20050714230501.4a9df11e.pj@sgi.com> <20050715140437.7399921f.pj@sgi.com> <20050715211210.GI15783@wotan.suse.de> <20050715214700.GJ15783@wotan.suse.de> <20050715220753.GK15783@wotan.suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Lameter Cc: Andi Kleen , Paul Jackson , kenneth.w.chen@intel.com, linux-mm@kvack.org, linux-ia64@vger.kernel.org On Fri, Jul 15, 2005 at 03:30:40PM -0700, Christoph Lameter wrote: > I cannot imagine that migrate pages make it into the kernel in its > current form. It combines multiple functionalities that need to be > separate (it does update the memory policy, clears the page cache, deals > with memory policy translations and then does heuristics to guess which > vma's to transfer) and then provides a complex function moving of pages > between groups of nodes. > > Therefore: > > 1. Updating the memory policy is something that can be useful in other > settings as well so it need to be separate. The patch we are discussing Not for external processes except in the narrow special case of migrating everything. External processes shouldn' t know about virtual addresses of other people. > 3. Memory policy translations better be done in user space. The batch > scheduler /sysadmin knows which node has what pages so it can easily > develop page movement scheme that is optimal for the process. I don't think the existing policies are complex enough to make this useful. The mapping for page migration for all of them is quite straight forward. -Andi