Re: [PATCH 4/9] cputlb: Hoist tlb portions in tlb_mmu_resize_locked

[Alistair Francis]

On Thu, Jan 9, 2020 at 12:52 PM Richard Henderson
<address@hidden> wrote:
>
> No functional change, but the smaller expressions make
> the code easier to read.
>
> Signed-off-by: Richard Henderson <address@hidden>

Reviewed-by: Alistair Francis <address@hidden>

Alistair

> ---
>  accel/tcg/cputlb.c | 35 +++++++++++++++++------------------
>  1 file changed, 17 insertions(+), 18 deletions(-)
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index 49c605b6d8..c7dc1dc85a 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -115,8 +115,8 @@ static void tlb_dyn_init(CPUArchState *env)
>
>  /**
>   * tlb_mmu_resize_locked() - perform TLB resize bookkeeping; resize if 
> necessary
> - * @env: CPU that owns the TLB
> - * @mmu_idx: MMU index of the TLB
> + * @desc: The CPUTLBDesc portion of the TLB
> + * @fast: The CPUTLBDescFast portion of the same TLB
>   *
>   * Called with tlb_lock_held.
>   *
> @@ -153,10 +153,9 @@ static void tlb_dyn_init(CPUArchState *env)
>   * high), since otherwise we are likely to have a significant amount of
>   * conflict misses.
>   */
> -static void tlb_mmu_resize_locked(CPUArchState *env, int mmu_idx)
> +static void tlb_mmu_resize_locked(CPUTLBDesc *desc, CPUTLBDescFast *fast)
>  {
> -    CPUTLBDesc *desc = &env_tlb(env)->d[mmu_idx];
> -    size_t old_size = tlb_n_entries(&env_tlb(env)->f[mmu_idx]);
> +    size_t old_size = tlb_n_entries(fast);
>      size_t rate;
>      size_t new_size = old_size;
>      int64_t now = get_clock_realtime();
> @@ -198,14 +197,15 @@ static void tlb_mmu_resize_locked(CPUArchState *env, 
> int mmu_idx)
>          return;
>      }
>
> -    g_free(env_tlb(env)->f[mmu_idx].table);
> -    g_free(env_tlb(env)->d[mmu_idx].iotlb);
> +    g_free(fast->table);
> +    g_free(desc->iotlb);
>
>      tlb_window_reset(desc, now, 0);
>      /* desc->n_used_entries is cleared by the caller */
> -    env_tlb(env)->f[mmu_idx].mask = (new_size - 1) << CPU_TLB_ENTRY_BITS;
> -    env_tlb(env)->f[mmu_idx].table = g_try_new(CPUTLBEntry, new_size);
> -    env_tlb(env)->d[mmu_idx].iotlb = g_try_new(CPUIOTLBEntry, new_size);
> +    fast->mask = (new_size - 1) << CPU_TLB_ENTRY_BITS;
> +    fast->table = g_try_new(CPUTLBEntry, new_size);
> +    desc->iotlb = g_try_new(CPUIOTLBEntry, new_size);
> +
>      /*
>       * If the allocations fail, try smaller sizes. We just freed some
>       * memory, so going back to half of new_size has a good chance of 
> working.
> @@ -213,25 +213,24 @@ static void tlb_mmu_resize_locked(CPUArchState *env, 
> int mmu_idx)
>       * allocations to fail though, so we progressively reduce the allocation
>       * size, aborting if we cannot even allocate the smallest TLB we support.
>       */
> -    while (env_tlb(env)->f[mmu_idx].table == NULL ||
> -           env_tlb(env)->d[mmu_idx].iotlb == NULL) {
> +    while (fast->table == NULL || desc->iotlb == NULL) {
>          if (new_size == (1 << CPU_TLB_DYN_MIN_BITS)) {
>              error_report("%s: %s", __func__, strerror(errno));
>              abort();
>          }
>          new_size = MAX(new_size >> 1, 1 << CPU_TLB_DYN_MIN_BITS);
> -        env_tlb(env)->f[mmu_idx].mask = (new_size - 1) << CPU_TLB_ENTRY_BITS;
> +        fast->mask = (new_size - 1) << CPU_TLB_ENTRY_BITS;
>
> -        g_free(env_tlb(env)->f[mmu_idx].table);
> -        g_free(env_tlb(env)->d[mmu_idx].iotlb);
> -        env_tlb(env)->f[mmu_idx].table = g_try_new(CPUTLBEntry, new_size);
> -        env_tlb(env)->d[mmu_idx].iotlb = g_try_new(CPUIOTLBEntry, new_size);
> +        g_free(fast->table);
> +        g_free(desc->iotlb);
> +        fast->table = g_try_new(CPUTLBEntry, new_size);
> +        desc->iotlb = g_try_new(CPUIOTLBEntry, new_size);
>      }
>  }
>
>  static void tlb_flush_one_mmuidx_locked(CPUArchState *env, int mmu_idx)
>  {
> -    tlb_mmu_resize_locked(env, mmu_idx);
> +    tlb_mmu_resize_locked(&env_tlb(env)->d[mmu_idx], 
> &env_tlb(env)->f[mmu_idx]);
>      env_tlb(env)->d[mmu_idx].n_used_entries = 0;
>      env_tlb(env)->d[mmu_idx].large_page_addr = -1;
>      env_tlb(env)->d[mmu_idx].large_page_mask = -1;
> --
> 2.20.1
>
>