[Qemu-devel] [PATCH 1/2] cputlb: Use memset when flushing entries

[Qemu-devel] [PATCH 1/2] cputlb: Use memset when flushing entries

[Richard Henderson]

The size of tlb_table is 4k on a 64-bit host.  For overwriting
memory at this size, cacheline tricks can help.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 cputlb.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/cputlb.c b/cputlb.c
index fff0afb..d2da404 100644
--- a/cputlb.c
+++ b/cputlb.c
@@ -33,13 +33,6 @@
 /* statistics */
 int tlb_flush_count;
 
-static const CPUTLBEntry s_cputlb_empty_entry = {
-    .addr_read  = -1,
-    .addr_write = -1,
-    .addr_code  = -1,
-    .addend     = -1,
-};
-
 /* NOTE:
  * If flush_global is true (the usual case), flush all tlb entries.
  * If flush_global is false, flush (at least) all tlb entries not
@@ -55,7 +48,6 @@ static const CPUTLBEntry s_cputlb_empty_entry = {
 void tlb_flush(CPUArchState *env, int flush_global)
 {
     CPUState *cpu = ENV_GET_CPU(env);
-    int i;
 
 #if defined(DEBUG_TLB)
     printf("tlb_flush:\n");
@@ -64,14 +56,7 @@ void tlb_flush(CPUArchState *env, int flush_global)
        links while we are modifying them */
     cpu->current_tb = NULL;
 
-    for (i = 0; i < CPU_TLB_SIZE; i++) {
-        int mmu_idx;
-
-        for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
-            env->tlb_table[mmu_idx][i] = s_cputlb_empty_entry;
-        }
-    }
-
+    memset(env->tlb_table, -1, sizeof(env->tlb_table));
     memset(env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof (void *));
 
     env->tlb_flush_addr = -1;
@@ -87,7 +72,7 @@ static inline void tlb_flush_entry(CPUTLBEntry *tlb_entry, target_ulong addr)
                  (TARGET_PAGE_MASK | TLB_INVALID_MASK)) ||
         addr == (tlb_entry->addr_code &
                  (TARGET_PAGE_MASK | TLB_INVALID_MASK))) {
-        *tlb_entry = s_cputlb_empty_entry;
+        memset(tlb_entry, -1, sizeof(*tlb_entry));
     }
 }
 
-- 
1.8.3.1

[Qemu-devel] [PATCH 2/2] cputlb: Tidy memset of arrays

[Richard Henderson]

Don't duplicate the array length computation in the memset
when plain sizeof can produce the correct results.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 cputlb.c        | 2 +-
 translate-all.c | 5 ++---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/cputlb.c b/cputlb.c
index d2da404..9270055 100644
--- a/cputlb.c
+++ b/cputlb.c
@@ -57,7 +57,7 @@ void tlb_flush(CPUArchState *env, int flush_global)
     cpu->current_tb = NULL;
 
     memset(env->tlb_table, -1, sizeof(env->tlb_table));
-    memset(env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof (void *));
+    memset(env->tb_jmp_cache, 0, sizeof(env->tb_jmp_cache));
 
     env->tlb_flush_addr = -1;
     env->tlb_flush_mask = 0;
diff --git a/translate-all.c b/translate-all.c
index aeda54d..66755b1 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -699,11 +699,10 @@ void tb_flush(CPUArchState *env1)
     CPU_FOREACH(cpu) {
         CPUArchState *env = cpu->env_ptr;
 
-        memset(env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof(void *));
+        memset(env->tb_jmp_cache, 0, sizeof(env->tb_jmp_cache));
     }
 
-    memset(tcg_ctx.tb_ctx.tb_phys_hash, 0,
-            CODE_GEN_PHYS_HASH_SIZE * sizeof(void *));
+    memset(tcg_ctx.tb_ctx.tb_phys_hash, 0, sizeof(tcg_ctx.tb_ctx.tb_phys_hash));
     page_flush_tb();
 
     tcg_ctx.code_gen_ptr = tcg_ctx.code_gen_buffer;
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH 2/2] cputlb: Tidy memset of arrays

[Aurelien Jarno]

On Sat, Dec 07, 2013 at 10:44:52AM +1300, Richard Henderson wrote:
> Don't duplicate the array length computation in the memset
> when plain sizeof can produce the correct results.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  cputlb.c        | 2 +-
>  translate-all.c | 5 ++---
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/cputlb.c b/cputlb.c
> index d2da404..9270055 100644
> --- a/cputlb.c
> +++ b/cputlb.c
> @@ -57,7 +57,7 @@ void tlb_flush(CPUArchState *env, int flush_global)
>      cpu->current_tb = NULL;
>  
>      memset(env->tlb_table, -1, sizeof(env->tlb_table));
> -    memset(env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof (void *));
> +    memset(env->tb_jmp_cache, 0, sizeof(env->tb_jmp_cache));
>  
>      env->tlb_flush_addr = -1;
>      env->tlb_flush_mask = 0;
> diff --git a/translate-all.c b/translate-all.c
> index aeda54d..66755b1 100644
> --- a/translate-all.c
> +++ b/translate-all.c
> @@ -699,11 +699,10 @@ void tb_flush(CPUArchState *env1)
>      CPU_FOREACH(cpu) {
>          CPUArchState *env = cpu->env_ptr;
>  
> -        memset(env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof(void *));
> +        memset(env->tb_jmp_cache, 0, sizeof(env->tb_jmp_cache));
>      }
>  
> -    memset(tcg_ctx.tb_ctx.tb_phys_hash, 0,
> -            CODE_GEN_PHYS_HASH_SIZE * sizeof(void *));
> +    memset(tcg_ctx.tb_ctx.tb_phys_hash, 0, sizeof(tcg_ctx.tb_ctx.tb_phys_hash));
>      page_flush_tb();
>  
>      tcg_ctx.code_gen_ptr = tcg_ctx.code_gen_buffer;

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net

Re: [Qemu-devel] [PATCH 1/2] cputlb: Use memset when flushing entries

[Aurelien Jarno]

On Sat, Dec 07, 2013 at 10:44:51AM +1300, Richard Henderson wrote:
> The size of tlb_table is 4k on a 64-bit host.  For overwriting
> memory at this size, cacheline tricks can help.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  cputlb.c | 19 ++-----------------
>  1 file changed, 2 insertions(+), 17 deletions(-)
> 
> diff --git a/cputlb.c b/cputlb.c
> index fff0afb..d2da404 100644
> --- a/cputlb.c
> +++ b/cputlb.c
> @@ -33,13 +33,6 @@
>  /* statistics */
>  int tlb_flush_count;
>  
> -static const CPUTLBEntry s_cputlb_empty_entry = {
> -    .addr_read  = -1,
> -    .addr_write = -1,
> -    .addr_code  = -1,
> -    .addend     = -1,
> -};
> -
>  /* NOTE:
>   * If flush_global is true (the usual case), flush all tlb entries.
>   * If flush_global is false, flush (at least) all tlb entries not
> @@ -55,7 +48,6 @@ static const CPUTLBEntry s_cputlb_empty_entry = {
>  void tlb_flush(CPUArchState *env, int flush_global)
>  {
>      CPUState *cpu = ENV_GET_CPU(env);
> -    int i;
>  
>  #if defined(DEBUG_TLB)
>      printf("tlb_flush:\n");
> @@ -64,14 +56,7 @@ void tlb_flush(CPUArchState *env, int flush_global)
>         links while we are modifying them */
>      cpu->current_tb = NULL;
>  
> -    for (i = 0; i < CPU_TLB_SIZE; i++) {
> -        int mmu_idx;
> -
> -        for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
> -            env->tlb_table[mmu_idx][i] = s_cputlb_empty_entry;
> -        }
> -    }
> -
> +    memset(env->tlb_table, -1, sizeof(env->tlb_table));
>      memset(env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof (void *));
>  
>      env->tlb_flush_addr = -1;
> @@ -87,7 +72,7 @@ static inline void tlb_flush_entry(CPUTLBEntry *tlb_entry, target_ulong addr)
>                   (TARGET_PAGE_MASK | TLB_INVALID_MASK)) ||
>          addr == (tlb_entry->addr_code &
>                   (TARGET_PAGE_MASK | TLB_INVALID_MASK))) {
> -        *tlb_entry = s_cputlb_empty_entry;
> +        memset(tlb_entry, -1, sizeof(*tlb_entry));
>      }
>  }

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net

Re: [Qemu-devel] [PATCH 1/2] cputlb: Use memset when flushing entries

[Andreas Färber]

Am 22.12.2013 19:04, schrieb Aurelien Jarno:
> On Sat, Dec 07, 2013 at 10:44:51AM +1300, Richard Henderson wrote:
>> The size of tlb_table is 4k on a 64-bit host.  For overwriting
>> memory at this size, cacheline tricks can help.
>>
>> Signed-off-by: Richard Henderson <rth@twiddle.net>
>> ---
>>  cputlb.c | 19 ++-----------------
>>  1 file changed, 2 insertions(+), 17 deletions(-)
[...]
> 
> Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

Don't spot a matching cover letter - thanks, applied both to qom-cpu:
https://github.com/afaerber/qemu-cpu/commits/qom-cpu

Andreas

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