| Message ID | 20230726074732.32981-1-wang_yang6662023@163.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | RISC-V: Use GCC __builtin_prefetch() to implement prefetch() | expand |
Hey, On Wed, Jul 26, 2023 at 03:47:32PM +0800, wang_yang wrote: > GCC's __builtin_prefetch() was introduced a long time ago, all supported GCC > versions have it.So this patch is to use it for implementing the prefetch. > > RISC-V Cache Management Operation instructions has been supported by GCC last > year.you can refer to > https://github.com/gcc-mirror/gcc/commit/3df3ca9014f94fe4af07444fea19b4ab29ba8e73 This should be in a Link: tag. > It is worth noting that CPU based on RISC-V should support Zicbop extension. How do you intend determining whether the CPU supports Zicbop? > This has been already done on other architectures (see the commit: > https://github.com/torvalds/linux/commit/0453fb3c528c5eb3483441a466b24a4cb409eec5). That's not how to describe commits, please see how that is done elsewhere in the git history. > > Signed-off-by: Wang Yang <yangwang@nj.iscas.ac.cn> WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line) #6: GCC's __builtin_prefetch() was introduced a long time ago, all supported GCC ERROR: Missing Signed-off-by: line by nominal patch author 'wang_yang <wang_yang6662023@163.com>' > --- > arch/riscv/include/asm/processor.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h > index c950a8d9edef..f16d4c85ca5b 100644 > --- a/arch/riscv/include/asm/processor.h > +++ b/arch/riscv/include/asm/processor.h > @@ -70,6 +70,17 @@ extern void start_thread(struct pt_regs *regs, > > extern unsigned long __get_wchan(struct task_struct *p); > > +#define ARCH_HAS_PREFETCH > +static inline void prefetch(const void *ptr) > +{ > + __builtin_prefetch(ptr, 0, 3); As far as I can tell, this does not do anything and will be removed by the compiler. Please take a look at how other extensions are implemented. Also, why 3? (Your answer should be in the commit message) Thanks, Conor. > +} > + > +#define ARCH_HAS_PREFETCHW > +static inline void prefetchw(const void *ptr) > +{ > + __builtin_prefetch(ptr, 1, 3); > +} > > static inline void wait_for_interrupt(void) > { > -- > 2.34.1 >
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index c950a8d9edef..f16d4c85ca5b 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -70,6 +70,17 @@ extern void start_thread(struct pt_regs *regs, extern unsigned long __get_wchan(struct task_struct *p); +#define ARCH_HAS_PREFETCH +static inline void prefetch(const void *ptr) +{ + __builtin_prefetch(ptr, 0, 3); +} + +#define ARCH_HAS_PREFETCHW +static inline void prefetchw(const void *ptr) +{ + __builtin_prefetch(ptr, 1, 3); +} static inline void wait_for_interrupt(void) {
GCC's __builtin_prefetch() was introduced a long time ago, all supported GCC versions have it.So this patch is to use it for implementing the prefetch. RISC-V Cache Management Operation instructions has been supported by GCC last year.you can refer to https://github.com/gcc-mirror/gcc/commit/3df3ca9014f94fe4af07444fea19b4ab29ba8e73 It is worth noting that CPU based on RISC-V should support Zicbop extension. This has been already done on other architectures (see the commit: https://github.com/torvalds/linux/commit/0453fb3c528c5eb3483441a466b24a4cb409eec5). Signed-off-by: Wang Yang <yangwang@nj.iscas.ac.cn> --- arch/riscv/include/asm/processor.h | 11 +++++++++++ 1 file changed, 11 insertions(+)