On Mon, Apr 13, 2026 at 10:36 PM Stephen Hemminger <[email protected]> wrote: > > On SMT systems when a spinloop is done without a pause > it may cause excessive latency. This problem was found > by the fix_empty_spinloops coccinelle script. > > Signed-off-by: Stephen Hemminger <[email protected]>
rte_pause() translates to YIELD instruction. Since cnxk is an integrated SoC and it is a single threaded core, it won't help on anything other than adding one instruction bit more latency. In general 3/3 devtool is good. Please send a it separate version so that 3/3 patches can be merged through the main tree. --------------- The YIELD instruction write up from ARMv8 manual. YIELD is a hint instruction in the ARMv8-A architecture. It tells the CPU that the current hardware thread is doing nothing useful right now (typically spinning in a busy-wait loop), so the processor may reallocate shared execution resources to other hardware threads. On SMT (multithreaded) cores, this can give sibling hardware threads more resources, improving overall throughput. On most current single-threaded ARM cores, YIELD executes as a NOP — it has no microarchitectural effect, but it's architecturally valid and harmless. It does not put the core to sleep (unlike WFE/WFI). It's a pure hint: it never changes program correctness, only potentially performance/fairness. -------------
