vandersonmr <vanderson...@gmail.com> writes:
> Adding tb_stats [start|pause|stop|filter] command to hmp.
> This allows controlling the collection of statistics.
> It is also possible to set the level of collection:
> all, jit, or exec.
>
> The goal of this command is to allow the dynamic exploration
> of the TCG behavior and quality. Therefore, for now, a
> corresponding QMP command is not worthwhile.
>
> Signed-off-by: Vanderson M. do Rosario <vanderson...@gmail.com>
> ---
> accel/tcg/tb-stats.c | 107 ++++++++++++++++++++++++++++++++++++++++
> hmp-commands.hx | 17 +++++++
> include/exec/tb-stats.h | 13 +++++
> include/qemu/log.h | 1 +
> monitor/misc.c | 40 +++++++++++++++
> 5 files changed, 178 insertions(+)
>
> diff --git a/accel/tcg/tb-stats.c b/accel/tcg/tb-stats.c
> index 44497d4f9b..6c330e1b02 100644
> --- a/accel/tcg/tb-stats.c
> +++ b/accel/tcg/tb-stats.c
> @@ -6,6 +6,9 @@
>
> #include "qemu/qemu-print.h"
>
> +/* only accessed in safe work */
> +static GList *last_search;
> +
> struct jit_profile_info {
> uint64_t translations;
> uint64_t aborted;
> @@ -104,4 +107,108 @@ void dump_jit_profile_info(TCGProfile *s)
> }
> }
>
> +static void dessaloc_tbstats(void *p, uint32_t hash, void *userp)
> +{
> + g_free(p);
> +}
surely free_tbstats would be a better name?
> +
> +void clean_tbstats(void)
> +{
> + /* remove all tb_stats */
> + qht_iter(&tb_ctx.tb_stats, dessaloc_tbstats, NULL);
> + qht_destroy(&tb_ctx.tb_stats);
> +}
> +
> +static void reset_tbstats_flag(void *p, uint32_t hash, void *userp)
> +{
> + uint32_t flag = *((int *)userp);
> + TBStatistics *tbs = p;
> + tbs->stats_enabled = flag;
> +}
> +
> +void set_tbstats_flags(uint32_t flag)
> +{
> + /* iterate over tbstats setting their flag as TB_NOTHING */
> + qht_iter(&tb_ctx.tb_stats, reset_tbstats_flag, &flag);
> +}
> +
> +void do_hmp_tbstats_safe(CPUState *cpu, run_on_cpu_data icmd)
> +{
> + struct TbstatsCommand *cmdinfo = icmd.host_ptr;
> + int cmd = cmdinfo->cmd;
> + uint32_t level = cmdinfo->level;
> +
> + /* for safe, always pause TB generation while running this commands */
> + mmap_lock();
This doesn't serialise in all cases - in fact it's running as safe work
which is our serial case. The mmap_lock is really only needed for code
generation in linux-user. I think the lock/unlock can be dropped from
these operations.
> +
> + switch (cmd) {
> + case START:
> + if (tb_stats_collection_paused()) {
> + set_tbstats_flags(level);
> + } else {
> + if (tb_stats_collection_enabled()) {
> + qemu_printf("TB information already being recorded");
> + return;
> + }
> + qht_init(&tb_ctx.tb_stats, tb_stats_cmp, CODE_GEN_HTABLE_SIZE,
> + QHT_MODE_AUTO_RESIZE);
I'm wary of initialising this in multiple places. Maybe move this to
enable_collect_tb_stats and drop the initialisation in tb_htable_init.
> + }
> +
> + set_default_tbstats_flag(level);
> + enable_collect_tb_stats();
> + tb_flush(cpu);
> + break;
> + case PAUSE:
> + if (!tb_stats_collection_enabled()) {
> + qemu_printf("TB information not being recorded");
> + return;
> + }
> +
> + /* Continue to create TBStatistic structures but stop collecting
> statistics */
> + pause_collect_tb_stats();
> + tb_flush(cpu);
> + set_default_tbstats_flag(TB_NOTHING);
> + set_tbstats_flags(TB_PAUSED);
Minor style suggestion - make the tb_flush the last thing you do once
you have moved things around. You are in safe work so nothing should be
happening anyway and it reads better.
> + break;
> + case STOP:
> + if (!tb_stats_collection_enabled()) {
> + qemu_printf("TB information not being recorded");
> + return;
> + }
> +
> + /* Dissalloc all TBStatistics structures and stop creating new ones
> */
> + disable_collect_tb_stats();
> + tb_flush(cpu);
> + clean_tbstats();
As above.
> + break;
> + case FILTER:
> + if (!tb_stats_collection_enabled()) {
> + qemu_printf("TB information not being recorded");
> + return;
> + }
> + if (!last_search) {
> + qemu_printf("no search on record! execute info tbs before
> filtering!");
> + return;
> + }
> +
> + tb_flush(cpu);
> + set_default_tbstats_flag(TB_NOTHING);
> +
> + /* Set all tbstats as paused, then return only the ones from
> last_search */
> + pause_collect_tb_stats();
> + set_tbstats_flags(TB_PAUSED);
> +
> + for (GList *iter = last_search; iter; iter = g_list_next(iter)) {
> + TBStatistics *tbs = iter->data;
> + tbs->stats_enabled = level;
> + }
If we are only interested in tracking the N hotestest at this point we
want to prevent allocation of new TBStats and free all the unused ones?
> +
> + break;
> + default: /* INVALID */
g_assert_not_reached()? This would be an internal bug if we ever sent
the wrong command?
> + break;
> + }
> +
> + mmap_unlock();
> + g_free(cmdinfo);
> +}
>
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index bfa5681dd2..419898751e 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -1885,6 +1885,23 @@ STEXI
> @findex qemu-io
> Executes a qemu-io command on the given block device.
>
> +ETEXI
> +#if defined(CONFIG_TCG)
> + {
> + .name = "tb_stats",
> + .args_type = "command:s,level:s?",
> + .params = "command [stats_level]",
> + .help = "Control tb statistics collection:"
> + "tb_stats (start|pause|stop|filter)
> [all|jit_stats|exec_stats]",
What does filter do?
> + .cmd = hmp_tbstats,
> + },
> +#endif
> +
> +STEXI
> +@item tb_stats
> +@findex
> +Control recording tb statistics
> +
> ETEXI
>
> {
> diff --git a/include/exec/tb-stats.h b/include/exec/tb-stats.h
> index 7d775f2c0d..d1debd3262 100644
> --- a/include/exec/tb-stats.h
> +++ b/include/exec/tb-stats.h
> @@ -6,6 +6,9 @@
> #include "exec/tb-context.h"
> #include "tcg.h"
>
> +enum SortBy { SORT_BY_HOTNESS, SORT_BY_HG /* Host/Guest */, SORT_BY_SPILLS };
> +enum TbstatsCmd { START, PAUSE, STOP, FILTER };
> +
> #define tb_stats_enabled(tb, JIT_STATS) \
> (tb && tb->tb_stats && (tb->tb_stats->stats_enabled & JIT_STATS))
>
> @@ -60,4 +63,14 @@ bool tb_stats_cmp(const void *ap, const void *bp);
>
> void dump_jit_profile_info(TCGProfile *s);
>
> +void set_tbstats_flags(uint32_t flags);
> +void clean_tbstats(void);
> +
> +struct TbstatsCommand {
> + enum TbstatsCmd cmd;
> + uint32_t level;
> +};
> +
> +void do_hmp_tbstats_safe(CPUState *cpu, run_on_cpu_data icmd);
> +
> #endif
> diff --git a/include/qemu/log.h b/include/qemu/log.h
> index 93642603e5..47071d72c7 100644
> --- a/include/qemu/log.h
> +++ b/include/qemu/log.h
> @@ -133,6 +133,7 @@ void qemu_log_close(void);
> #define TB_NOTHING 0
> #define TB_EXEC_STATS (1 << 1)
> #define TB_JIT_STATS (1 << 2)
> +#define TB_PAUSED (1 << 3)
>
> void enable_collect_tb_stats(void);
> void disable_collect_tb_stats(void);
> diff --git a/monitor/misc.c b/monitor/misc.c
> index 00338c002a..aea9b0db4f 100644
> --- a/monitor/misc.c
> +++ b/monitor/misc.c
> @@ -459,6 +459,46 @@ static void hmp_info_registers(Monitor *mon, const QDict
> *qdict)
> }
>
> #ifdef CONFIG_TCG
> +static void hmp_tbstats(Monitor *mon, const QDict *qdict)
> +{
> + if (!tcg_enabled()) {
> + error_report("TB information is only available with accel=tcg");
> + return;
> + }
> +
> + char *cmd = (char *) qdict_get_try_str(qdict, "command");
> + enum TbstatsCmd icmd = -1;
> +
> + if (strcmp(cmd, "start") == 0) {
> + icmd = START;
> + } else if (strcmp(cmd, "pause") == 0) {
> + icmd = PAUSE;
> + } else if (strcmp(cmd, "stop") == 0) {
> + icmd = STOP;
> + } else if (strcmp(cmd, "filter") == 0) {
> + icmd = FILTER;
> + } else {
> + error_report("invalid command!");
> + }
> +
> + char *slevel = (char *) qdict_get_try_str(qdict, "level");
> + uint32_t level = TB_EXEC_STATS | TB_JIT_STATS;
> + if (slevel) {
> + if (strcmp(slevel, "jit_stats") == 0) {
> + level = TB_JIT_STATS;
> + } else if (strcmp(slevel, "exec_stats") == 0) {
> + level = TB_EXEC_STATS;
> + }
> + }
> +
> + struct TbstatsCommand *tbscommand = g_new0(struct TbstatsCommand, 1);
> + tbscommand->cmd = icmd;
> + tbscommand->level = level;
It might be worth considering squashing these into a single pointer to
avoid the allocation and free?
> + async_safe_run_on_cpu(first_cpu, do_hmp_tbstats_safe,
> + RUN_ON_CPU_HOST_PTR(tbscommand));
> +
> +}
> +
> static void hmp_info_jit(Monitor *mon, const QDict *qdict)
> {
> if (!tcg_enabled()) {
--
Alex Bennée
