Re: [PATCH] plugins/syscall: Added a table-like summary output

[Mahmoud Mandour <ma.mandourr@gmail.com>]

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On Thu, Apr 15, 2021 at 5:20 PM Mahmoud Mandour <ma.mandourr@gmail.com>
wrote:

> Added a table-like output which contains the total number of calls
> for each used syscall along with the number of errors that occurred.
>
> Per-call tracing is still available through supplying the argument
> ``print`` to the plugin.
>
> Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
> ---
>  tests/plugin/syscall.c | 94 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 88 insertions(+), 6 deletions(-)
>
> diff --git a/tests/plugin/syscall.c b/tests/plugin/syscall.c
> index 53ee2ab6c4..b92340c636 100644
> --- a/tests/plugin/syscall.c
> +++ b/tests/plugin/syscall.c
> @@ -16,32 +16,114 @@
>
>  QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
>
> +typedef struct {
> +    int64_t calls;
> +    int64_t errors;
> +} SyscallStats;
> +
> +static GHashTable *syscalls_statistics;
> +
> +static bool percall_print;
> +
>  static void vcpu_syscall(qemu_plugin_id_t id, unsigned int vcpu_index,
>                           int64_t num, uint64_t a1, uint64_t a2,
>                           uint64_t a3, uint64_t a4, uint64_t a5,
>                           uint64_t a6, uint64_t a7, uint64_t a8)
>  {
> -    g_autofree gchar *out = g_strdup_printf("syscall #%" PRIi64 "\n",
> num);
> -    qemu_plugin_outs(out);
> +    if (!percall_print) {
> +        SyscallStats *syscall_entry;
> +
> +        syscall_entry =
> +            (SyscallStats *) g_hash_table_lookup(syscalls_statistics,
> +                                                  GINT_TO_POINTER(num));
> +
> +        if (!syscall_entry) {
> +            syscall_entry = g_new(SyscallStats, 1);
> +            syscall_entry->calls = 1;
> +            syscall_entry->errors = 0;
> +
> +            g_hash_table_insert(syscalls_statistics, GINT_TO_POINTER(num),
> +                                (gpointer) syscall_entry);
> +        } else {
> +            syscall_entry->calls++;
> +        }
> +    } else {
> +        g_autofree gchar *out = g_strdup_printf("syscall #%" PRIi64 "\n",
> num);
> +        qemu_plugin_outs(out);
> +    }
>  }
>
>  static void vcpu_syscall_ret(qemu_plugin_id_t id, unsigned int vcpu_idx,
>                               int64_t num, int64_t ret)
> +{
> +    if (!percall_print) {
> +        SyscallStats *syscall_entry;
> +
> +        syscall_entry =
> +            (SyscallStats *) g_hash_table_lookup(syscalls_statistics,
> +                                                  GINT_TO_POINTER(num));
> +        if (!syscall_entry) {
> +            qemu_plugin_outs(g_strdup_printf("%" PRIi64 "\n", num));
> +        }
> +        if (ret < 0) {
> +            syscall_entry->errors++;
> +        }
> +    } else {
> +        g_autofree gchar *out;
> +        out = g_strdup_printf("syscall #%" PRIi64 " returned -> %" PRIi64
> "\n",
> +                num, ret);
> +        qemu_plugin_outs(out);
> +    }
> +}
> +
> +/*
> ************************************************************************* */
> +
> +void print_entry(gpointer key, gpointer val, gpointer user_data)
>  {
>      g_autofree gchar *out;
> -    out = g_strdup_printf("syscall #%" PRIi64 " returned -> %" PRIi64
> "\n",
> -            num, ret);
> +    int64_t syscall_num = (int64_t) key;
> +    SyscallStats *syscall_entry = (SyscallStats *) val;
> +    out = g_strdup_printf(
> +        "%-13" PRIi64 "%-6" PRIi64 " %" PRIi64 "\n",
> +        syscall_num, syscall_entry->calls, syscall_entry->errors);
>      qemu_plugin_outs(out);
>  }
>
> -/*
> ************************************************************************* */
> +static void plugin_exit(qemu_plugin_id_t id, void *p)
> +{
> +    if (!percall_print) {
> +        qemu_plugin_outs("syscall no.  calls  errors\n");
> +        g_hash_table_foreach(syscalls_statistics, &print_entry, NULL);
> +    }
> +}
>
> -static void plugin_exit(qemu_plugin_id_t id, void *p) {}
> +void free_entry(gpointer entry)
> +{
> +    g_free(entry);
> +}
>
>  QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
>                                             const qemu_info_t *info,
>                                             int argc, char **argv)
>  {
> +    int i;
> +
> +    for (i = 0; i < argc; i++) {
> +        char *opt = argv[i];
> +        if (g_strcmp0(opt, "print") == 0) {
> +            percall_print = true;
> +        } else {
> +            fprintf(stderr, "unsupported argument: %s\n", opt);
> +            return -1;
> +        }
> +    }
> +
> +    if (!percall_print) {
> +        syscalls_statistics =
> +            g_hash_table_new_full(g_direct_hash, g_direct_equal,
> +                    NULL, &free_entry);
> +    }
> +
>      qemu_plugin_register_vcpu_syscall_cb(id, vcpu_syscall);
>      qemu_plugin_register_vcpu_syscall_ret_cb(id, vcpu_syscall_ret);
>      qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
> --
> 2.25.1
>
>
Hello. I just realized that this hunk:

static void vcpu_syscall_ret(qemu_plugin_id_t id, unsigned int vcpu_idx,
>                               int64_t num, int64_t ret)
> +{
> +        // ......
> +        if (!syscall_entry) {
> +            qemu_plugin_outs(g_strdup_printf("%" PRIi64 "\n", num));
> +        }
>

Is completely superfluous. I think I had it for debugging purposes.
Should I resend without it or can you omit it from the patch?

Yours,
Mahmoud

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