vandersonmr <vanderson...@gmail.com> writes:
> We want to store statistics for each TB even after flushes.
> We do not want to modify or grow the TB struct.
> So we create a new struct to contain this statistics and
> link it to each TB while they are created.
>
> Signed-off-by: Vanderson M. do Rosario <vanderson...@gmail.com>
> ---
> accel/tcg/translate-all.c | 40 +++++++++++++++++++++++++++++++++++++++
> include/exec/exec-all.h | 21 ++++++++++++++++++++
> include/exec/tb-context.h | 1 +
> include/qemu/log.h | 1 +
> 4 files changed, 63 insertions(+)
>
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index 5d1e08b169..f7e99f90e0 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -1118,6 +1118,18 @@ static inline void code_gen_alloc(size_t tb_size)
> }
> }
>
> +static gint statistics_cmp(gconstpointer p1, gconstpointer p2)
> +{
> + const TBStatistics *a = (TBStatistics *) p1;
> + const TBStatistics *b = (TBStatistics *) p2;
> +
> + return (a->pc == b->pc &&
> + a->cs_base == b->cs_base &&
> + a->flags == b->flags &&
> + a->page_addr[0] == b->page_addr[0] &&
> + a->page_addr[1] == b->page_addr[1]) ? 0 : 1;
> +}
> +
There are a bunch of white space errors that need fixing up as you
probably already know from patchew ;-)
> static bool tb_cmp(const void *ap, const void *bp)
> {
> const TranslationBlock *a = ap;
> @@ -1586,6 +1598,29 @@ static inline void tb_page_add(PageDesc *p,
> TranslationBlock *tb,
> #endif
> }
>
> +static void tb_insert_statistics_structure(TranslationBlock *tb) {
> + TBStatistics *new_stats = g_new0(TBStatistics, 1);
> + new_stats->pc = tb->pc;
> + new_stats->cs_base = tb->cs_base;
> + new_stats->flags = tb->flags;
> + new_stats->page_addr[0] = tb->page_addr[0];
> + new_stats->page_addr[1] = tb->page_addr[1];
> +
> + GList *lookup_result = g_list_find_custom(tb_ctx.tb_statistics,
> new_stats, statistics_cmp);
> +
> + if (lookup_result) {
> + /* If there is already a TBStatistic for this TB from a
> previous flush
> + * then just make the new TB point to the older TBStatistic
> + */
> + free(new_stats);
> + tb->tb_stats = lookup_result->data;
> + } else {
> + /* If not, then points to the new tb_statistics and add it to
> the hash */
> + tb->tb_stats = new_stats;
> + tb_ctx.tb_statistics = g_list_prepend(tb_ctx.tb_statistics,
> new_stats);
This is going to race as nothing prevents two threads attempting to
insert records at the same time.
> + }
> +}
> +
> /* add a new TB and link it to the physical page tables. phys_page2 is
> * (-1) to indicate that only one page contains the TB.
> *
> @@ -1636,6 +1671,11 @@ tb_link_page(TranslationBlock *tb, tb_page_addr_t
> phys_pc,
> void *existing_tb = NULL;
> uint32_t h;
>
> + if (qemu_loglevel_mask(CPU_LOG_HOT_TBS)) {
> + /* create and link to its TB a structure to store statistics */
> + tb_insert_statistics_structure(tb);
> + }
> +
> /* add in the hash table */
> h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags &
> CF_HASH_MASK,
> tb->trace_vcpu_dstate);
Perhaps we could just have a second qht array which allows for
"unlocked" insertion of record. You could take advantage of the fact the
hash would be the same:
h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags & CF_HASH_MASK,
tb->trace_vcpu_dstate);
qht_insert(&tb_ctx.htable, tb, h, &existing_tb);
/* remove TB from the page(s) if we couldn't insert it */
if (unlikely(existing_tb)) {
...
tb = existing_tb;
} else if (qemu_loglevel_mask(CPU_LOG_HOT_TBS)) {
TBStatistics *new_stats = g_new0(TBStatistics, 1);
bool ok;
new_stats->pc = tb->pc;
new_stats->cs_base = tb->cs_base;
new_stats->flags = tb->flags;
new_stats->page_addr[0] = tb->page_addr[0];
new_stats->page_addr[1] = tb->page_addr[1];
ok = qht_insert(&tb_ctx.tb_stats, new_stats, h, NULL);
/*
* This should never fail as we succeeded in inserting the
* TB itself which means we haven't seen this combination yet.
*/
g_assert(ok);
}
It would also avoid the clunkiness of having to allocate and then
freeing an unused structure.
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 16034ee651..359100ef3b 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -324,6 +324,24 @@ static inline void
> tlb_flush_by_mmuidx_all_cpus_synced(CPUState *cpu,
> #define CODE_GEN_AVG_BLOCK_SIZE 150
> #endif
>
> +typedef struct TBStatistics TBStatistics;
> +
> +/*
> + * This struct stores statistics such as execution count of the
> TranslationBlocks.
> + * Each TB has its own TBStatistics. TBStatistics is suppose to live even
> after
> + * flushes.
> + */
> +struct TBStatistics {
> + target_ulong pc;
> + target_ulong cs_base;
> + uint32_t flags;
> + tb_page_addr_t page_addr[2];
> +
> + // total number of times that the related TB have being executed
No c++ style comments
> + uint32_t exec_count;
> + uint32_t exec_count_overflows;
> +};
> +
> /*
> * Translation Cache-related fields of a TB.
> * This struct exists just for convenience; we keep track of TB's in a binary
> @@ -403,6 +421,9 @@ struct TranslationBlock {
> uintptr_t jmp_list_head;
> uintptr_t jmp_list_next[2];
> uintptr_t jmp_dest[2];
> +
> + // Pointer to a struct where statistics from the TB is stored
No c++ style comments
> + TBStatistics *tb_stats;
> };
>
> extern bool parallel_cpus;
> diff --git a/include/exec/tb-context.h b/include/exec/tb-context.h
> index feb585e0a7..a78ce92e60 100644
> --- a/include/exec/tb-context.h
> +++ b/include/exec/tb-context.h
> @@ -35,6 +35,7 @@ struct TBContext {
>
> /* statistics */
> unsigned tb_flush_count;
> + GList *tb_statistics;
> };
>
> extern TBContext tb_ctx;
> diff --git a/include/qemu/log.h b/include/qemu/log.h
> index b097a6cae1..2fca65dd01 100644
> --- a/include/qemu/log.h
> +++ b/include/qemu/log.h
> @@ -45,6 +45,7 @@ static inline bool qemu_log_separate(void)
> /* LOG_TRACE (1 << 15) is defined in log-for-trace.h */
> #define CPU_LOG_TB_OP_IND (1 << 16)
> #define CPU_LOG_TB_FPU (1 << 17)
> +#define CPU_LOG_HOT_TBS (1 << 18)
>
> /* Lock output for a series of related logs. Since this is not needed
> * for a single qemu_log / qemu_log_mask / qemu_log_mask_and_addr, we
--
Alex Bennée
