On Sat, 2018-12-15 at 13:23 -0800, David Miller wrote: > From: Paolo Abeni <pab...@redhat.com> > Date: Fri, 14 Dec 2018 11:51:56 +0100 > > > The spectre v2 counter-measures, aka retpolines, are a source of measurable > > overhead[1]. We can partially address that when the function pointer refers > > to > > a builtin symbol resorting to a list of tests vs well-known builtin > > function and > > direct calls. > > > > Experimental results show that replacing a single indirect call via > > retpoline with several branches and a direct call gives performance gains > > even when multiple branches are added - 5 or more, as reported in [2]. > > > > This may lead to some uglification around the indirect calls. In netconf > > 2018 > > Eric Dumazet described a technique to hide the most relevant part of the > > needed > > boilerplate with some macro help. > > > > This series is a [re-]implementation of such idea, exposing the introduced > > helpers in a new header file. They are later leveraged to avoid the indirect > > call overhead in the GRO path, when possible. > > > > Overall this gives > 10% performance improvement for UDP GRO benchmark and > > smaller but measurable for TCP syn flood. > > > > The added infra can be used in follow-up patches to cope with retpoline > > overhead > > in other points of the networking stack (e.g. at the qdisc layer) and > > possibly > > even in other subsystems. > ... > > Series applied, I'll push this out after a build check completes.
Again, I messed it! I'm really sorry to waste everybody's time. I was unable to give proper coverage with different configs. I tested vs.: CONFIG_IPV6=ymn CONFIG_INET=yn but # CONFIG_RETPOLINE is not set fooled me. The following patch should fix. I'll try more configurations. Is there any way to try/tests all kbuild robot configs? Please feel free to give me an hard stop if this sounds too much a trial and error thing. Paolo -- diff --git a/include/linux/indirect_call_wrapper.h b/include/linux/indirect_call_wrapper.h index 7c8b7f4..00d7e8e9 100644 --- a/include/linux/indirect_call_wrapper.h +++ b/include/linux/indirect_call_wrapper.h @@ -28,8 +28,8 @@ #define INDIRECT_CALLABLE_SCOPE #else -#define INDIRECT_CALL_1(f, name, ...) f(__VA_ARGS__) -#define INDIRECT_CALL_2(f, name, ...) f(__VA_ARGS__) +#define INDIRECT_CALL_1(f, f1, ...) f(__VA_ARGS__) +#define INDIRECT_CALL_2(f, f2, f1, ...) f(__VA_ARGS__) #define INDIRECT_CALLABLE_DECLARE(f) #define INDIRECT_CALLABLE_SCOPE static #endif
