Excerpts from Matthew Wilcox's message of September 1, 2021 1:25 pm: > On Wed, Sep 01, 2021 at 11:07:41AM +0800, Shijie Huang wrote: >> In the NUMA, we only have one page cache for each file. For the >> program/shared libraries, the >> remote-access delays longer then the local-access. >> >> So, is it possible to implement the per-node page cache for >> programs/libraries? > > At this point, we have no way to support text replication within a > process. So what you're suggesting (if implemented) would work for > processes which limit themselves to a single node. That is, if you > have a system with CPUs 0-3 on node 0 and CPUs 4-7 on node 1, a process > which only works on node 0 or only works on node 1 will get text on the > appropriate node. > > If there's a process which runs on both nodes 0 and 1, there's no support > for per-node PGDs. So it will get a mix of pages from nodes 0 and 1, > and that doesn't necessarily seem like a big win. I haven't yet dived > into how hard it would be to make mm->pgd a per-node allocation. > > I have been thinking about this a bit; one of our internal performance > teams flagged the potential performance win to me a few months ago. > I don't have a concrete design for text replication yet; there have been > various attempts over the years, but none were particularly compelling. What was not compelling about it? https://lists.openwall.net/linux-kernel/2007/07/27/112 What are the other attempts? Thanks, Nick
