Re: [Qemu-devel] [PATCH v3 01/39] tcg: Fold CPUTLBWindow into CPUTLBDesc

[Alistair Francis]

On Tue, May 7, 2019 at 5:10 PM Richard Henderson
<address@hidden> wrote:
>
> Reviewed-by: Alex Bennée <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>

Reviewed-by: Alistair Francis <address@hidden>

Alistair

> ---
>  include/exec/cpu-defs.h | 17 ++++-------------
>  accel/tcg/cputlb.c      | 24 ++++++++++++------------
>  2 files changed, 16 insertions(+), 25 deletions(-)
>
> diff --git a/include/exec/cpu-defs.h b/include/exec/cpu-defs.h
> index 8f2a848bf5..52d150aaf1 100644
> --- a/include/exec/cpu-defs.h
> +++ b/include/exec/cpu-defs.h
> @@ -127,18 +127,6 @@ typedef struct CPUIOTLBEntry {
>      MemTxAttrs attrs;
>  } CPUIOTLBEntry;
>
> -/**
> - * struct CPUTLBWindow
> - * @begin_ns: host time (in ns) at the beginning of the time window
> - * @max_entries: maximum number of entries observed in the window
> - *
> - * See also: tlb_mmu_resize_locked()
> - */
> -typedef struct CPUTLBWindow {
> -    int64_t begin_ns;
> -    size_t max_entries;
> -} CPUTLBWindow;
> -
>  typedef struct CPUTLBDesc {
>      /*
>       * Describe a region covering all of the large pages allocated
> @@ -148,9 +136,12 @@ typedef struct CPUTLBDesc {
>       */
>      target_ulong large_page_addr;
>      target_ulong large_page_mask;
> +    /* host time (in ns) at the beginning of the time window */
> +    int64_t window_begin_ns;
> +    /* maximum number of entries observed in the window */
> +    size_t window_max_entries;
>      /* The next index to use in the tlb victim table.  */
>      size_t vindex;
> -    CPUTLBWindow window;
>      size_t n_used_entries;
>  } CPUTLBDesc;
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index f2f618217d..6c7593235c 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -79,11 +79,11 @@ static inline size_t sizeof_tlb(CPUArchState *env, 
> uintptr_t mmu_idx)
>      return env->tlb_mask[mmu_idx] + (1 << CPU_TLB_ENTRY_BITS);
>  }
>
> -static void tlb_window_reset(CPUTLBWindow *window, int64_t ns,
> +static void tlb_window_reset(CPUTLBDesc *desc, int64_t ns,
>                               size_t max_entries)
>  {
> -    window->begin_ns = ns;
> -    window->max_entries = max_entries;
> +    desc->window_begin_ns = ns;
> +    desc->window_max_entries = max_entries;
>  }
>
>  static void tlb_dyn_init(CPUArchState *env)
> @@ -94,7 +94,7 @@ static void tlb_dyn_init(CPUArchState *env)
>          CPUTLBDesc *desc = &env->tlb_d[i];
>          size_t n_entries = 1 << CPU_TLB_DYN_DEFAULT_BITS;
>
> -        tlb_window_reset(&desc->window, get_clock_realtime(), 0);
> +        tlb_window_reset(desc, get_clock_realtime(), 0);
>          desc->n_used_entries = 0;
>          env->tlb_mask[i] = (n_entries - 1) << CPU_TLB_ENTRY_BITS;
>          env->tlb_table[i] = g_new(CPUTLBEntry, n_entries);
> @@ -151,18 +151,18 @@ static void tlb_mmu_resize_locked(CPUArchState *env, 
> int mmu_idx)
>      int64_t now = get_clock_realtime();
>      int64_t window_len_ms = 100;
>      int64_t window_len_ns = window_len_ms * 1000 * 1000;
> -    bool window_expired = now > desc->window.begin_ns + window_len_ns;
> +    bool window_expired = now > desc->window_begin_ns + window_len_ns;
>
> -    if (desc->n_used_entries > desc->window.max_entries) {
> -        desc->window.max_entries = desc->n_used_entries;
> +    if (desc->n_used_entries > desc->window_max_entries) {
> +        desc->window_max_entries = desc->n_used_entries;
>      }
> -    rate = desc->window.max_entries * 100 / old_size;
> +    rate = desc->window_max_entries * 100 / old_size;
>
>      if (rate > 70) {
>          new_size = MIN(old_size << 1, 1 << CPU_TLB_DYN_MAX_BITS);
>      } else if (rate < 30 && window_expired) {
> -        size_t ceil = pow2ceil(desc->window.max_entries);
> -        size_t expected_rate = desc->window.max_entries * 100 / ceil;
> +        size_t ceil = pow2ceil(desc->window_max_entries);
> +        size_t expected_rate = desc->window_max_entries * 100 / ceil;
>
>          /*
>           * Avoid undersizing when the max number of entries seen is just 
> below
> @@ -182,7 +182,7 @@ static void tlb_mmu_resize_locked(CPUArchState *env, int 
> mmu_idx)
>
>      if (new_size == old_size) {
>          if (window_expired) {
> -            tlb_window_reset(&desc->window, now, desc->n_used_entries);
> +            tlb_window_reset(desc, now, desc->n_used_entries);
>          }
>          return;
>      }
> @@ -190,7 +190,7 @@ static void tlb_mmu_resize_locked(CPUArchState *env, int 
> mmu_idx)
>      g_free(env->tlb_table[mmu_idx]);
>      g_free(env->iotlb[mmu_idx]);
>
> -    tlb_window_reset(&desc->window, now, 0);
> +    tlb_window_reset(desc, now, 0);
>      /* desc->n_used_entries is cleared by the caller */
>      env->tlb_mask[mmu_idx] = (new_size - 1) << CPU_TLB_ENTRY_BITS;
>      env->tlb_table[mmu_idx] = g_try_new(CPUTLBEntry, new_size);
> --
> 2.17.1
>
>