Re: [Qemu-devel] [RFC 6/6] cputlb: dynamically resize TLBs based on use rate

[Richard Henderson <richard.henderson@linaro.org>]

On 10/6/18 2:45 PM, Emilio G. Cota wrote:
> @@ -122,6 +123,39 @@ size_t tlb_flush_count(void)
>      return count;
>  }
>  
> +/* Call with tlb_lock held */
> +static void tlb_mmu_resize_locked(CPUArchState *env, int mmu_idx)
> +{
> +    CPUTLBDesc *desc = &env->tlb_desc[mmu_idx];
> +    size_t rate = desc->used * 100 / desc->size;
> +    size_t new_size = desc->size;
> +
> +    if (rate == 100) {
> +        new_size = MIN(desc->size << 2, 1 << TCG_TARGET_TLB_MAX_INDEX_BITS);
> +    } else if (rate > 70) {
> +        new_size = MIN(desc->size << 1, 1 << TCG_TARGET_TLB_MAX_INDEX_BITS);
> +    } else if (rate < 30) {
> +        desc->n_flushes_low_rate++;
> +        if (desc->n_flushes_low_rate == 100) {
> +            new_size = MAX(desc->size >> 1, 1 << MIN_CPU_TLB_BITS);
> +            desc->n_flushes_low_rate = 0;
> +        }
> +    }
> +
> +    if (new_size == desc->size) {

s/desc->size/old_size/g
Otherwise it looks plausible as a first cut.


r~