29/04/2021 16:28, Ruifeng Wang: > From: Thomas Monjalon <tho...@monjalon.net> > > 28/04/2021 11:30, Ruifeng Wang: > > > From: David Marchand <david.march...@redhat.com> > > > > On Sun, Apr 25, 2021 at 7:57 AM Ruifeng Wang <ruifeng.w...@arm.com> > > > > wrote: > > > > > > > > > > The rte_wait_until_equal_xxx APIs abstract the functionality of > > > > > 'polling for a memory location to become equal to a given value'[1]. > > > > > > > > > > Use the API for the rte spinlock and ring implementations. > > > > > With the wait until equal APIs being stable, changes will not impact > > > > > ABI. > > > > > > > > Afaics, there is no ARM target with WFE enabled and we lost ability > > > > to enable WFE support with removal of the make build system. > > > > > > WFE can be enabled with direct meson file change. > > > WFE is not intended to be enabled by default. It can be enabled based > > > on benchmarking result on hardware. > > > > > > > > $ git grep RTE_ARM_USE_WFE > > > > config/arm/meson.build: ['RTE_ARM_USE_WFE', false], > > > > lib/eal/arm/include/rte_pause_64.h:#ifdef RTE_ARM_USE_WFE > > > > > > > > How did you enable WFE to test this series? > > > > > > I modified meson file to test. > > > Tests were also done with WFE disabled to make sure no degradation with > > generic implementation. > > > > I don't understand the usage. > > Which platform should use it? > > Platforms that implement WFE semantic (e.g. N1) can use. > The user can enable this feature for power efficiency purpose. But there is > something to > note as described in commit message 1be7855d77 when the API was introduced. > > > Should it be a compile-time option? > > Yes, it should be a compile-time option. > It can be configured via c_args meson option?
+Cc Bruce for discussing how to enable such feature. The problem with c_args is that the application has no way to know.
