Messages in this thread | | | From | Christoph Müllner <> | Date | Thu, 18 Apr 2024 14:26:12 +0200 | Subject | Re: [RFC 0/2] riscv: Idle thread using Zawrs extension |
| |
On Thu, Apr 18, 2024 at 1:50 PM Xu Lu <luxu.kernel@bytedance.com> wrote: > > This patch series introduces a new implementation of idle thread using > Zawrs extension.
This overlaps with the following series: https://lore.kernel.org/all/20240315134009.580167-7-ajones@ventanamicro.com/
BR Christoph
> > The Zawrs[0] extension introduces two new instructions named WRS.STO and > WRS.NTO in RISC-V. When software registers a reservation set using LR > instruction, a subsequent WRS.STO or WRS.NTO instruction will cause the > hart to stall in a low-power state until a store happens to the > reservation set or an interrupt becomes pending. The difference between > these two instructions is that WRS.STO will terminate stall after an > implementation-defined timeout while WRS.NTO won't. > > This patch series implements idle thread using WRS.NTO instruction. > Besides, we found there is no need to send a real IPI to wake up an idle > CPU. Instead, we write IPI information to the reservation set of an idle > CPU to wake it up and let it handle IPI quickly, without going through > tranditional interrupt handling routine. > > [0] https://github.com/riscv/riscv-zawrs/blob/main/zawrs.adoc > > Xu Lu (2): > riscv: process: Introduce idle thread using Zawrs extension > riscv: Use Zawrs to accelerate IPI to idle cpu > > arch/riscv/Kconfig | 24 +++++++ > arch/riscv/include/asm/cpuidle.h | 11 +--- > arch/riscv/include/asm/hwcap.h | 1 + > arch/riscv/include/asm/processor.h | 31 +++++++++ > arch/riscv/include/asm/smp.h | 14 ++++ > arch/riscv/kernel/cpu.c | 5 ++ > arch/riscv/kernel/cpufeature.c | 1 + > arch/riscv/kernel/process.c | 102 ++++++++++++++++++++++++++++- > arch/riscv/kernel/smp.c | 39 +++++++---- > 9 files changed, 205 insertions(+), 23 deletions(-) > > -- > 2.20.1 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
| |