[PATCH] RISC-V: only flush icache when it has VM_EXEC set
Alexandre Ghiti
alex at ghiti.fr
Tue Jan 9 22:47:48 PST 2024
Hi Yangyu,
On 09/01/2024 19:48, Yangyu Chen wrote:
> As I-Cache flush on current RISC-V needs to send IPIs to every CPU cores
> in the system is very costly, limiting flush_icache_mm to be called only
> when vma->vm_flags has VM_EXEC can help minimize the frequency of these
> operations. It improves performance and reduces disturbances when
Which platform did you test this patchset? Do you have any measurement
of the performance improvements?
> copy_from_user_page is needed such as profiling with perf.
>
> For I-D coherence concerns, it will not fail if such a page adds VM_EXEC
> flags in the future since we have checked it in the __set_pte_at function.
>
> Signed-off-by: Yangyu Chen <cyy at cyyself.name>
> ---
> arch/riscv/include/asm/cacheflush.h | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
> index 3cb53c4df27c..915f532dc336 100644
> --- a/arch/riscv/include/asm/cacheflush.h
> +++ b/arch/riscv/include/asm/cacheflush.h
> @@ -33,8 +33,11 @@ static inline void flush_dcache_page(struct page *page)
> * so instead we just flush the whole thing.
> */
> #define flush_icache_range(start, end) flush_icache_all()
> -#define flush_icache_user_page(vma, pg, addr, len) \
> - flush_icache_mm(vma->vm_mm, 0)
> +#define flush_icache_user_page(vma, pg, addr, len) \
> +do { \
> + if (vma->vm_flags & VM_EXEC) \
> + flush_icache_mm(vma->vm_mm, 0); \
> +} while (0)
>
> #ifdef CONFIG_64BIT
> #define flush_cache_vmap(start, end) flush_tlb_kernel_range(start, end)
Otherwise, it looks good to me, so you can add:
Reviewed-by: Alexandre Ghiti <alexghiti at rivosinc.com>
Thanks,
Alex
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