> -----Original Message----- > From: Huang Shijie [mailto:shijie@xxxxxxxxxxxxxxxxxxxxxx] > Sent: Saturday, September 4, 2021 3:16 AM > To: Florian Weimer <fweimer@xxxxxxxxxx> > Cc: Huang Shijie via Libc-alpha <libc-alpha@xxxxxxxxxxxxxx>; > carlos@xxxxxxxxxxxxxxxx; zwang@xxxxxxxxxxxxxxxxxxx; > patches@xxxxxxxxxxxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; > torvalds@xxxxxxxxxxxxxxxxxxxx; viro@xxxxxxxxxxxxxxxxxx; willy@xxxxxxxxxxxxx; > Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx>; linux-mm@xxxxxxxxx > Subject: Re: [PATCH] Add LD_NUMA_REPLICATION for glibc > > 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. > Hi Shijie, Thanks! Could we have some benchmark data for this patch? I assume it will benefit frontend-bound large workset which might face relatively more icache miss? > > Thanks > Huang Shijie Thanks Barry
