Re: [Qemu-devel] [PATCH v4 7/7] monitor: adding info tbs, tb, and coverset

[Alex Bennée]

Alex Bennée <address@hidden> writes:

> vandersonmr <address@hidden> writes:
>
>> Adding info [tbs|tb|coverset] commands to HMP.
>> These commands allow the exploration of TBs
>> generated by the TCG. Understand which one
>> hotter, with more guest/host instructions...
>> and examine their guest, host and IR code.
>>
>> The goal of this command is to allow the dynamic exploration
>> of TCG behavior and code quality. Therefore, for now, a
>> corresponding QMP command is not worthwhile.
>>
>> Signed-off-by: vandersonmr <address@hidden>
>> ---
>>  accel/tcg/tb-stats.c         | 275 +++++++++++++++++++++++++++++++++++
>>  hmp-commands-info.hx         |  23 +++
>>  include/exec/tb-stats.h      |  37 +++++
>>  include/qemu/log-for-trace.h |   2 +
>>  include/qemu/log.h           |   1 +
>>  linux-user/exit.c            |   4 +
>>  monitor/misc.c               |  71 +++++++++
>>  util/log.c                   |  26 +++-
>>  8 files changed, 431 insertions(+), 8 deletions(-)
>>
>> diff --git a/accel/tcg/tb-stats.c b/accel/tcg/tb-stats.c
>> index 6c330e1b02..85a16cd563 100644
>> --- a/accel/tcg/tb-stats.c
>> +++ b/accel/tcg/tb-stats.c
>> @@ -212,3 +212,278 @@ void do_hmp_tbstats_safe(CPUState *cpu, 
>> run_on_cpu_data icmd)
>>      g_free(cmdinfo);
>>  }
>>
>> +static void collect_tb_stats(void *p, uint32_t hash, void *userp)
>> +{
>> +    last_search = g_list_prepend(last_search, p);
>> +}
>> +
>> +static void dump_tb_header(TBStatistics *tbs)
>> +{
>> +    unsigned g = tbs->translations.total ?
>> +        tbs->code.num_guest_inst / tbs->translations.total : 0;
>> +    unsigned ops = tbs->translations.total ?
>> +        tbs->code.num_tcg_ops / tbs->translations.total : 0;
>> +    unsigned ops_opt = tbs->translations.total ?
>> +        tbs->code.num_tcg_ops_opt / tbs->translations.total : 0;
>> +    unsigned h = tbs->translations.total ?
>> +        tbs->code.num_host_inst / tbs->translations.total : 0;
>> +    unsigned spills = tbs->translations.total ?
>> +        tbs->code.spills / tbs->translations.total : 0;
>> +
>> +    float guest_host_prop = g ? ((float) h / g) : 0;
>> +
>> +    qemu_log("TB%d: phys:0x"TB_PAGE_ADDR_FMT" virt:0x"TARGET_FMT_lx
>> +             " flags:%#08x (trans:%lu uncached:%lu exec:%lu ints: g:%u 
>> op:%u op_opt:%u h:%u h/g:%.2f spills:%d)\n",
>> +             tbs->display_id,
>> +             tbs->phys_pc, tbs->pc, tbs->flags,
>> +             tbs->translations.total, tbs->translations.uncached,
>> +             tbs->executions.total, g, ops, ops_opt, h, guest_host_prop,
>> +             spills);
>> +}
>> +
>> +static gint
>> +inverse_sort_tbs(gconstpointer p1, gconstpointer p2, gpointer psort_by)
>> +{
>> +    const TBStatistics *tbs1 = (TBStatistics *) p1;
>> +    const TBStatistics *tbs2 = (TBStatistics *) p2;
>> +    int sort_by = *((int *) psort_by);
>> +    unsigned long c1 = 0;
>> +    unsigned long c2 = 0;
>> +
>> +    if (likely(sort_by == SORT_BY_SPILLS)) {
>> +        c1 = tbs1->code.spills;
>> +        c2 = tbs2->code.spills;
>> +    } else if (likely(sort_by == SORT_BY_HOTNESS)) {
>> +        c1 = tbs1->executions.total;
>> +        c2 = tbs2->executions.total;
>> +    } else if (likely(sort_by == SORT_BY_HG)) {
>> +        if (tbs1->code.num_guest_inst == 0) {
>> +            return -1;
>> +        }
>> +        if (tbs2->code.num_guest_inst == 0) {
>> +            return 1;
>> +        }
>> +
>> +        float a = (float) tbs1->code.num_host_inst / 
>> tbs1->code.num_guest_inst;
>> +        float b = (float) tbs2->code.num_host_inst / 
>> tbs2->code.num_guest_inst;
>> +        c1 = a <= b ? 0 : 1;
>> +        c2 = a <= b ? 1 : 0;
>> +    }
>> +
>> +    return c1 < c2 ? 1 : c1 == c2 ? 0 : -1;
>> +}
>> +
>> +static void do_dump_coverset_info(int percentage)
>> +{
>> +    uint64_t total_exec_count = 0;
>> +    uint64_t covered_exec_count = 0;
>> +    unsigned coverset_size = 0;
>> +    int id = 1;
>> +    GList *i;
>> +
>> +    g_list_free(last_search);
>> +    last_search = NULL;
>> +
>> +    qht_iter(&tb_ctx.tb_stats, collect_tb_stats, NULL);
>> +
>> +    int sort_by = SORT_BY_HOTNESS;
>> +    last_search = g_list_sort_with_data(last_search, inverse_sort_tbs, 
>> &sort_by);
>> +
>> +    if (!last_search) {
>> +        qemu_log("No data collected yet\n");
>> +        return;
>> +    }
>> +
>> +    /* Compute total execution count for all tbs */
>> +    for (i = last_search; i; i = i->next) {
>> +        TBStatistics *tbs = (TBStatistics *) i->data;
>> +        total_exec_count += tbs->executions.total * 
>> tbs->code.num_guest_inst;
>> +    }
>> +
>> +    for (i = last_search; i; i = i->next) {
>> +        TBStatistics *tbs = (TBStatistics *) i->data;
>> +        covered_exec_count += tbs->executions.total * 
>> tbs->code.num_guest_inst;
>> +        tbs->display_id = id++;
>> +        coverset_size++;
>> +        dump_tb_header(tbs);
>> +
>> +        /* Iterate and display tbs until reach the percentage count cover */
>> +        if (((double) covered_exec_count / total_exec_count) >
>> +                ((double) percentage / 100)) {
>> +            break;
>> +        }
>> +    }
>> +
>> +    qemu_log("\n------------------------------\n");
>> +    qemu_log("# of TBs to reach %d%% of the total of guest insts exec: 
>> %u\t",
>> +                percentage, coverset_size);
>> +    qemu_log("Total of guest insts exec: %lu\n", total_exec_count);
>> +    qemu_log("\n------------------------------\n");
>> +
>> +    /* free the unused bits */
>> +    if (i) {
>> +        if (i->next) {
>> +            i->next->prev = NULL;
>> +        }
>> +        g_list_free(i->next);
>> +        i->next = NULL;
>> +    }
>> +}
>> +
>> +static void do_dump_tbs_info(int count, int sort_by)
>> +{
>> +    int id = 1;
>> +    GList *i;
>> +
>> +    g_list_free(last_search);
>> +    last_search = NULL;
>> +
>> +    qht_iter(&tb_ctx.tb_stats, collect_tb_stats, NULL);
>> +
>> +    last_search = g_list_sort_with_data(last_search, inverse_sort_tbs,
>> +                                        &sort_by);
>> +
>> +    if (!last_search) {
>> +        qemu_printf("No data collected yet!\n");
>> +        return;
>> +    }
>> +
>> +    for (i = last_search; i && count--; i = i->next) {
>> +        TBStatistics *tbs = (TBStatistics *) i->data;
>> +        tbs->display_id = id++;
>> +        dump_tb_header(tbs);
>> +    }
>> +
>> +    /* free the unused bits */
>> +    if (i) {
>> +        if (i->next) {
>> +            i->next->prev = NULL;
>> +        }
>> +        g_list_free(i->next);
>> +        i->next = NULL;
>> +    }
>> +}
>> +
>> +static void
>> +do_dump_coverset_info_safe(CPUState *cpu, run_on_cpu_data percentage)
>> +{
>> +    qemu_log_to_monitor(true);
>> +    do_dump_coverset_info(percentage.host_int);
>> +    qemu_log_to_monitor(false);
>> +}
>> +
>> +struct tbs_dump_info {
>> +    int count;
>> +    int sort_by;
>> +};
>> +
>> +static void do_dump_tbs_info_safe(CPUState *cpu, run_on_cpu_data tbdi)
>> +{
>> +    struct tbs_dump_info *info = tbdi.host_ptr;
>> +    qemu_log_to_monitor(true);
>> +    do_dump_tbs_info(info->count, info->sort_by);
>> +    qemu_log_to_monitor(false);
>> +    g_free(info);
>> +}
>> +
>> +/*
>> + * When we dump_tbs_info on a live system via the HMP we want to
>> + * ensure the system is quiessent before we start outputting stuff.
>> + * Otherwise we could pollute the output with other logging output.
>> + */
>> +void dump_coverset_info(int percentage, bool use_monitor)
>> +{
>> +    if (use_monitor) {
>> +        async_safe_run_on_cpu(first_cpu, do_dump_coverset_info_safe,
>> +                              RUN_ON_CPU_HOST_INT(percentage));
>> +    } else {
>> +        do_dump_coverset_info(percentage);
>> +    }
>> +}
>> +
>> +void dump_tbs_info(int count, int sort_by, bool use_monitor)
>> +{
>> +    if (use_monitor) {
>> +        struct tbs_dump_info *tbdi = g_new(struct tbs_dump_info, 1);
>> +        tbdi->count = count;
>> +        tbdi->sort_by = sort_by;
>> +        async_safe_run_on_cpu(first_cpu, do_dump_tbs_info_safe,
>> +                              RUN_ON_CPU_HOST_PTR(tbdi));
>> +    } else {
>> +        do_dump_tbs_info(count, sort_by);
>> +    }
>> +}
>> +
>> +static void do_tb_dump_with_statistics(TBStatistics *tbs, int log_flags)
>> +{
>> +    CPUState *cpu = current_cpu;
>> +    uint32_t cflags = curr_cflags() | CF_NOCACHE;
>> +    int old_log_flags = qemu_loglevel;
>> +    TranslationBlock *tb = NULL;
>> +
>> +    qemu_set_log(log_flags);
>> +
>> +    qemu_log("\n------------------------------\n");
>> +    dump_tb_header(tbs);
>> +
>> +    if (sigsetjmp(cpu->jmp_env, 0) == 0) {
>> +        mmap_lock();
>> +        tb = tb_gen_code(cpu, tbs->pc, tbs->cs_base, tbs->flags, cflags);
>> +        tb_phys_invalidate(tb, -1);
>> +        mmap_unlock();
>> +    } else {
>> +        /*
>> +         * The mmap_lock is dropped by tb_gen_code if it runs out of
>> +         * memory.
>> +         */
>> +        fprintf(stderr, "%s: dbg failed!\n", __func__);
>> +        assert_no_pages_locked();
>> +    }
>
> So this fails if we can't generate a TB as tcg_tb_remove(NULL) will barf
> (this was the crash I was seeing). However with two additional patches
> from my plugin series:
>
>   translate-all: use cpu_in_exclusive_work_context() in tb_flush
>   translate-all: use cpu_in_exclusive_work_context() in tb_flush
>
> We can do a simple repeat operation:
>
> @@ -420,6 +421,7 @@ static void do_tb_dump_with_statistics(TBStatistics *tbs, 
> int log_flags)
>
>      qemu_log("\n------------------------------\n");
>      dump_tb_header(tbs);
> + redo:
>
>      if (sigsetjmp(cpu->jmp_env, 0) == 0) {
>          mmap_lock();
> @@ -433,6 +435,7 @@ static void do_tb_dump_with_statistics(TBStatistics *tbs, 
> int log_flags)
>           */
>          fprintf(stderr, "%s: dbg failed!\n", __func__);
>          assert_no_pages_locked();
> +        goto redo;
>      }
>
> Because the tb_flush triggered by the generation code will have occured
> straight away.
>
> I'd suggest cherry picking those two patches into your next series.

Hmm not quite enough because we need to handle the case that we cannot
re-translate because the page has been mapped out.

>
>> +
>> +    qemu_set_log(old_log_flags);
>> +
>> +    tcg_tb_remove(tb);
>> +}
>> +
>> +struct tb_dump_info {
>> +    int id;
>> +    int log_flags;
>> +    bool use_monitor;
>> +};
>> +
>> +static void do_dump_tb_info_safe(CPUState *cpu, run_on_cpu_data info)
>> +{
>> +    struct tb_dump_info *tbdi = (struct tb_dump_info *) info.host_ptr;
>> +    GList *iter;
>> +
>> +    if (!last_search) {
>> +        qemu_printf("no search on record");
>> +        return;
>> +    }
>> +    qemu_log_to_monitor(tbdi->use_monitor);
>> +
>> +    for (iter = last_search; iter; iter = g_list_next(iter)) {
>> +        TBStatistics *tbs = iter->data;
>> +        if (tbs->display_id == tbdi->id) {
>> +            do_tb_dump_with_statistics(tbs, tbdi->log_flags);
>> +            break;
>> +        }
>> +    }
>> +    qemu_log_to_monitor(false);
>> +    g_free(tbdi);
>> +}
>> +
>> +void dump_tb_info(int id, int log_mask, bool use_monitor)
>> +{
>> +    struct tb_dump_info *tbdi = g_new(struct tb_dump_info, 1);
>> +
>> +    tbdi->id = id;
>> +    tbdi->log_flags = log_mask;
>> +    tbdi->use_monitor = use_monitor;
>> +
>> +    async_safe_run_on_cpu(first_cpu, do_dump_tb_info_safe,
>> +                          RUN_ON_CPU_HOST_PTR(tbdi));
>> +
>> +    /* tbdi free'd by do_dump_tb_info_safe */
>> +}
>> +
>> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
>> index c59444c461..761c76619b 100644
>> --- a/hmp-commands-info.hx
>> +++ b/hmp-commands-info.hx
>> @@ -289,6 +289,29 @@ ETEXI
>>          .help       = "show dynamic compiler info",
>>          .cmd        = hmp_info_jit,
>>      },
>> +    {
>> +        .name       = "tbs",
>> +        .args_type  = "number:i?,sortedby:s?",
>> +        .params     = "[number sortedby]",
>> +        .help       = "show a [number] translated blocks sorted by 
>> [sortedby]"
>> +                      "sortedby opts: hotness hg",
>> +        .cmd        = hmp_info_tbs,
>> +    },
>> +    {
>> +        .name       = "tb",
>> +        .args_type  = "id:i,flags:s?",
>> +        .params     = "id [log1[,...] flags]",
>> +        .help       = "show information about one translated block by id",
>> +        .cmd        = hmp_info_tb,
>> +    },
>> +    {
>> +        .name       = "coverset",
>> +        .args_type  = "number:i?",
>> +        .params     = "[number]",
>> +        .help       = "show hottest translated blocks neccesary to cover"
>> +                      "[number]% of the execution count",
>> +        .cmd        = hmp_info_coverset,
>> +    },
>>  #endif
>>
>>  STEXI
>> diff --git a/include/exec/tb-stats.h b/include/exec/tb-stats.h
>> index d1debd3262..e2ab1068c3 100644
>> --- a/include/exec/tb-stats.h
>> +++ b/include/exec/tb-stats.h
>> @@ -57,6 +57,9 @@ struct TBStatistics {
>>          unsigned long uncached;
>>          unsigned long spanning;
>>      } translations;
>> +
>> +    /* HMP information - used for referring to previous search */
>> +    int display_id;
>>  };
>>
>>  bool tb_stats_cmp(const void *ap, const void *bp);
>> @@ -73,4 +76,38 @@ struct TbstatsCommand {
>>
>>  void do_hmp_tbstats_safe(CPUState *cpu, run_on_cpu_data icmd);
>>
>> +/**
>> + * dump_coverset_info: report the hottest blocks to cover n% of execution
>> + *
>> + * @percentage: cover set percentage
>> + * @use_monitor: redirect output to monitor
>> + *
>> + * Report the hottest blocks to either the log or monitor
>> + */
>> +void dump_coverset_info(int percentage, bool use_monitor);
>> +
>> +
>> +/**
>> + * dump_tbs_info: report the hottest blocks
>> + *
>> + * @count: the limit of hotblocks
>> + * @sort_by: property in which the dump will be sorted
>> + * @use_monitor: redirect output to monitor
>> + *
>> + * Report the hottest blocks to either the log or monitor
>> + */
>> +void dump_tbs_info(int count, int sort_by, bool use_monitor);
>> +
>> +/**
>> + * dump_tb_info: dump information about one TB
>> + *
>> + * @id: the display id of the block (from previous search)
>> + * @mask: the temporary logging mask
>> + * @Use_monitor: redirect output to monitor
>> + *
>> + * Re-run a translation of a block at addr for the purposes of debug output
>> + */
>> +void dump_tb_info(int id, int log_mask, bool use_monitor);
>> +
>> +
>>  #endif
>> diff --git a/include/qemu/log-for-trace.h b/include/qemu/log-for-trace.h
>> index 2f0a5b080e..d65eb83037 100644
>> --- a/include/qemu/log-for-trace.h
>> +++ b/include/qemu/log-for-trace.h
>> @@ -21,6 +21,8 @@
>>  /* Private global variable, don't use */
>>  extern int qemu_loglevel;
>>
>> +extern int32_t max_num_hot_tbs_to_dump;
>> +
>>  #define LOG_TRACE          (1 << 15)
>>
>>  /* Returns true if a bit is set in the current loglevel mask */
>> diff --git a/include/qemu/log.h b/include/qemu/log.h
>> index 47071d72c7..27ba267faa 100644
>> --- a/include/qemu/log.h
>> +++ b/include/qemu/log.h
>> @@ -114,6 +114,7 @@ typedef struct QEMULogItem {
>>  extern const QEMULogItem qemu_log_items[];
>>
>>  void qemu_set_log(int log_flags);
>> +void qemu_log_to_monitor(bool enable);
>>  void qemu_log_needs_buffers(void);
>>  void qemu_set_log_filename(const char *filename, Error **errp);
>>  void qemu_set_dfilter_ranges(const char *ranges, Error **errp);
>> diff --git a/linux-user/exit.c b/linux-user/exit.c
>> index bdda720553..7226104959 100644
>> --- a/linux-user/exit.c
>> +++ b/linux-user/exit.c
>> @@ -28,6 +28,10 @@ extern void __gcov_dump(void);
>>
>>  void preexit_cleanup(CPUArchState *env, int code)
>>  {
>> +    if (tb_stats_collection_enabled()) {
>> +        dump_tbs_info(max_num_hot_tbs_to_dump, SORT_BY_HOTNESS, false);
>> +    }
>> +
>>  #ifdef TARGET_GPROF
>>          _mcleanup();
>>  #endif
>> diff --git a/monitor/misc.c b/monitor/misc.c
>> index aea9b0db4f..78ada8aa0e 100644
>> --- a/monitor/misc.c
>> +++ b/monitor/misc.c
>> @@ -499,6 +499,77 @@ static void hmp_tbstats(Monitor *mon, const QDict 
>> *qdict)
>>
>>  }
>>
>> +static void hmp_info_tbs(Monitor *mon, const QDict *qdict)
>> +{
>> +    int n;
>> +    const char *s = NULL;
>> +    if (!tcg_enabled()) {
>> +        error_report("TB information is only available with accel=tcg");
>> +        return;
>> +    }
>> +    if (!tb_ctx.tb_stats.map) {
>> +        error_report("no TB information recorded");
>> +        return;
>> +    }
>> +
>> +    n = qdict_get_try_int(qdict, "number", 10);
>> +    s = qdict_get_try_str(qdict, "sortedby");
>> +
>> +    int sortedby = 0;
>> +    if (s == NULL || strcmp(s, "hotness") == 0) {
>> +        sortedby = SORT_BY_HOTNESS;
>> +    } else if (strcmp(s, "hg") == 0) {
>> +        sortedby = SORT_BY_HG;
>> +    } else if (strcmp(s, "spills") == 0) {
>> +        sortedby = SORT_BY_SPILLS;
>> +    }
>> +
>> +    dump_tbs_info(n, sortedby, true);
>> +}
>> +
>> +static void hmp_info_tb(Monitor *mon, const QDict *qdict)
>> +{
>> +    const int id = qdict_get_int(qdict, "id");
>> +    const char *flags = qdict_get_try_str(qdict, "flags");
>> +    int mask;
>> +
>> +    if (!tcg_enabled()) {
>> +        error_report("TB information is only available with accel=tcg");
>> +        return;
>> +    }
>> +
>> +    mask = flags ? qemu_str_to_log_mask(flags) : CPU_LOG_TB_IN_ASM;
>> +
>> +    if (!mask) {
>> +        help_cmd(mon, "log");
>> +        return;
>> +    }
>> +
>> +    dump_tb_info(id, mask, true);
>> +}
>> +
>> +static void hmp_info_coverset(Monitor *mon, const QDict *qdict)
>> +{
>> +    int n;
>> +    if (!tcg_enabled()) {
>> +        error_report("TB information is only available with accel=tcg");
>> +        return;
>> +    }
>> +    if (!tb_stats_collection_enabled()) {
>> +        error_report("TB information not being recorded");
>> +        return;
>> +    }
>> +
>> +    n = qdict_get_try_int(qdict, "number", 90);
>> +
>> +    if (n < 0 || n > 100) {
>> +        error_report("Coverset percentage should be between 0 and 100");
>> +        return;
>> +    }
>> +
>> +    dump_coverset_info(n, true);
>> +}
>> +
>>  static void hmp_info_jit(Monitor *mon, const QDict *qdict)
>>  {
>>      if (!tcg_enabled()) {
>> diff --git a/util/log.c b/util/log.c
>> index 8109d19afb..7bfcbe3703 100644
>> --- a/util/log.c
>> +++ b/util/log.c
>> @@ -19,6 +19,7 @@
>>
>>  #include "qemu/osdep.h"
>>  #include "qemu/log.h"
>> +#include "qemu/qemu-print.h"
>>  #include "qemu/range.h"
>>  #include "qemu/error-report.h"
>>  #include "qapi/error.h"
>> @@ -31,25 +32,34 @@ int qemu_loglevel;
>>  static int log_append = 0;
>>  static GArray *debug_regions;
>>  int32_t max_num_hot_tbs_to_dump;
>> +static bool to_monitor;
>>
>>  /* Return the number of characters emitted.  */
>>  int qemu_log(const char *fmt, ...)
>>  {
>>      int ret = 0;
>> -    if (qemu_logfile) {
>> -        va_list ap;
>> -        va_start(ap, fmt);
>> +    va_list ap;
>> +    va_start(ap, fmt);
>> +
>> +    if (to_monitor) {
>> +        ret = qemu_vprintf(fmt, ap);
>> +    } else if (qemu_logfile) {
>>          ret = vfprintf(qemu_logfile, fmt, ap);
>> -        va_end(ap);
>> +    }
>> +    va_end(ap);
>>
>> -        /* Don't pass back error results.  */
>> -        if (ret < 0) {
>> -            ret = 0;
>> -        }
>> +    /* Don't pass back error results.  */
>> +    if (ret < 0) {
>> +        ret = 0;
>>      }
>>      return ret;
>>  }
>>
>> +void qemu_log_to_monitor(bool enable)
>> +{
>> +    to_monitor = enable;
>> +}
>> +
>>  static bool log_uses_own_buffers;
>>
>>  /* enable or disable low levels log */


--
Alex Bennée