On Fri, Sep 03, 2021 at 08:28:57AM +0200, Florian Weimer wrote: > * Huang Shijie via Libc-alpha: > > > This patch adds LD_NUMA_REPLICATION which influences the linkage of shared libraries at run time. > > > > If LD_NUMA_REPLICATION is set for program foo like this: > > #LD_NUMA_REPLICATION=1 ./foo > > > > At the time ld.so mmaps the shared libraries, it will uses > > mmap(, c->prot | PROT_WRITE, MAP_COPY | MAP_FILE | MAP_POPULATE,) > > for them, and the mmap will trigger COW(copy on write) for the shared > > libraries at the NUMA node which the program `foo` runs. After the > > COW, the foo will have a copy of the shared library segment(mmap > > covered) which belong to the same NUMA node. > > > > So when enable LD_NUMA_REPLICATION, it will consume more memory, > > but it will reduce the remote-access in NUMA. > > I think the kernel could do this in a much better way, avoiding > duplicating the pages within the same NUMA node. I think maybe only the per-NUMA-node page cache can avoid it.. > > The other issue is the temporary RWX mapping, which does not > interoperate well with some security hardening features. > Thanks for the feedback. I CC more people who may have interesting about this. Thanks Huang Shijie
