On Tue, Dec 11, 2018 at 9:40 AM Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, Dec 10, 2018 at 5:23 PM Andy Lutomirski <luto@xxxxxxxxxx> wrote: > > > > I'm seriously considering sending a patch to remove x32 support from > > upstream Linux. Here are some problems with it: > > I talked to Arnd (I think - we were talking about all the crazy ABI's, > but maybe it was with somebody else) about exactly this in Edinburgh. > > Apparently the main real use case is for extreme benchmarking. It's > the only use-case where the complexity of maintaining a whole > development environment and distro is worth it, it seems. Apparently a > number of Spec submissions have been done with the x32 model. > > I'm not opposed to trying to sunset the support, but let's see who complains.. I'm just a single user. I do rely on it though, FWIW. I hadn't finished my benchmarking in Edinburgh, but for my new machine that does kernel builds 24/7, I ended up going with x32 userspace (in a container). Main reason is that it's a free ~10% improvement in runtime over 64-bit. I.e. GCC-as-a-workload is quite a bit faster as x32, supposedly mostly due to smaller D cache footprints (I ran out of cycles to tinker with back and forth perf data collection and settled down on just running it). Running classic 32-bit (i386? i686? whatever it's called) is about half as good. I.e. even then I get a ~5% performance win. Less than x32, but still better than 64-bit userspace. -Olof
