Hello guys, This series got a lot of attention from ARM people and it seems ready for integration. But I did not see comment from other architectures, could you have a look please?
Thanks. -- David Marchand On Thu, Aug 22, 2019 at 8:13 AM Gavin Hu <gavin...@arm.com> wrote: > > DPDK has multiple use cases where the core repeatedly polls a location in > memory. This polling results in many cache and memory transactions. > > Arm architecture provides WFE (Wait For Event) instruction, which allows > the cpu core to enter a low power state until woken up by the update to the > memory location being polled. Thus reducing the cache and memory > transactions. > > x86 has the PAUSE hint instruction to reduce such overhead. > > The rte_wait_until_equal_xxx APIs abstract the functionality of 'polling > for a memory location to become equal to a given value'. > > For non-Arm platforms, these APIs are just wrappers around do-while loop > with rte_pause, so there are no performance differences. > > For Arm platforms, use of WFE can be configured using CONFIG_RTE_USE_WFE > option. It is disabled by default. > > Currently, use of WFE is supported only for aarch64 platforms. armv7 > platforms do support the WFE instruction, but they require explicit wake up > events(sev) and are less performannt. > > Testing shows that, performance varies across different platforms, with > some showing degradation. > > CONFIG_RTE_ARM_USE_WFE should be enabled depending on the performance > benchmarking on the target platforms. Power saving should be an bonus, > but currenly we don't have ways to characterize that. > > V4: > - rename the config as CONFIG_RTE_ARM_USE_WFE to indicate it applys to arm > only > - introduce a macro for assembly Skelton to reduce the duplication of code > - add one patch for nxp fslmc to address a compiling error > V3: > - Convert RFCs to patches > V2: > - Use inline functions instead of marcos > - Add load and compare in the beginning of the APIs > - Fix some style errors in asm inline > V1: > - Add the new APIs and use it for ring and locks > > Gavin Hu (6): > bus/fslmc: fix the conflicting dmb function > eal: add the APIs to wait until equal > ticketlock: use new API to reduce contention on aarch64 > ring: use wfe to wait for ring tail update on aarch64 > spinlock: use wfe to reduce contention on aarch64 > config: add WFE config entry for aarch64 > > config/arm/meson.build | 1 + > config/common_base | 6 +++++ > drivers/bus/fslmc/mc/fsl_mc_sys.h | 10 +++++--- > drivers/bus/fslmc/mc/mc_sys.c | 3 +-- > .../common/include/arch/arm/rte_pause_64.h | 30 > ++++++++++++++++++++++ > .../common/include/arch/arm/rte_spinlock.h | 25 ++++++++++++++++++ > lib/librte_eal/common/include/generic/rte_pause.h | 26 ++++++++++++++++++- > .../common/include/generic/rte_ticketlock.h | 3 +-- > lib/librte_ring/rte_ring_c11_mem.h | 4 +-- > lib/librte_ring/rte_ring_generic.h | 3 +-- > 10 files changed, 99 insertions(+), 12 deletions(-) > > -- > 2.7.4 >
