Re: [PATCH v4 09/16] perf tools: Enable indices setting syntax for BPF maps

Arnaldo Carvalho de Melo
2015-12-11T12:11:51Z

Em Tue, Dec 08, 2015 at 02:25:37AM +0000, Wang Nan escreveu:
> This patch introduce a new syntax to perf event parser:
>
> # perf record -e bpf_file.c/maps.mymap.value[0,3...5,7]=1234/ ...

Is the above example valid? Wouldn't this be "maps:mymap.value" ?

>
> By utilizing the basic facilities in bpf-loader.c which allow setting
> different slots in a BPF map separately, the newly introduced syntax
> allows perf to control specific elements in a BPF map.
>
> Test result:
>
> # cat ./test_bpf_map_3.c
> /************************ BEGIN **************************/
> #define SEC(NAME) __attribute__((section(NAME), used))
> enum bpf_map_type {
> BPF_MAP_TYPE_ARRAY = 2,
> };
> struct bpf_map_def {
> unsigned int type;
> unsigned int key_size;
> unsigned int value_size;
> unsigned int max_entries;
> };
> static void *(*map_lookup_elem)(struct bpf_map_def *, void *) =
> (void *)1;
> static int (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
> (void *)6;

Can you explain the above a bit more? What are the magic 1 and 6 values?

> struct bpf_map_def SEC("maps") channel = {
> .type = BPF_MAP_TYPE_ARRAY,
> .key_size = sizeof(int),
> .value_size = sizeof(unsigned char),
> .max_entries = 100,
> };

> SEC("func=hrtimer_nanosleep rqtp->tv_nsec")
> int func(void *ctx, int err, long nsec)
> {
> char fmt[] = "%ld\n";
> long usec = nsec * 0x10624dd3 >> 38; // nsec / 1000
> int key = (int)usec;
> unsigned char *pval = map_lookup_elem(&channel, &key);

So that "mymap.value" name doesn't needs to be specified here?

>
> if (!pval)
> return 0;
> bpf_trace_printk(fmt, sizeof(fmt), (unsigned char)*pval);
> return 0;
> }
> char _license[] SEC("license") = "GPL";
> int _version SEC("version") = LINUX_VERSION_CODE;
> /************************* END ***************************/
>
> Normal case:
> # echo "" > /sys/kernel/debug/tracing/trace
> # ./perf record -e './test_bpf_map_3.c/maps:channel.value[0,1,2,3...5]=101/' usleep 2
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.012 MB perf.data ]
> # cat /sys/kernel/debug/tracing/trace | grep usleep
> usleep-405 [004] d... 2745423.547822: : 101
> # ./perf record -e './test_bpf_map_3.c/maps:channel.value[0...9,20...29]=102,maps:channel.value[10...19]=103/' usleep 3
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.012 MB perf.data ]
> # ./perf record -e './test_bpf_map_3.c/maps:channel.value[0...9,20...29]=102,maps:channel.value[10...19]=103/' usleep 15
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.012 MB perf.data ]
> # cat /sys/kernel/debug/tracing/trace | grep usleep
> usleep-405 [004] d... 2745423.547822: : 101
> usleep-655 [006] d... 2745434.122814: : 102
> usleep-904 [006] d... 2745439.916264: : 103
> # ./perf record -e './test_bpf_map_3.c/maps:channel.value[all]=104/' usleep 99
> # cat /sys/kernel/debug/tracing/trace | grep usleep
> usleep-405 [004] d... 2745423.547822: : 101
> usleep-655 [006] d... 2745434.122814: : 102
> usleep-904 [006] d... 2745439.916264: : 103
> usleep-1537 [003] d... 2745538.053737: : 104
>
> Error case:
> # ./perf record -e './test_bpf_map_3.c/maps:channel.value[10...1000]=104/' usleep 99
> event syntax error: '..annel.value[10...1000]=104/'
> \___ Index too large
> Hint: Valid config terms:
> maps:[<arraymap>].value<indices>=[value]
> maps:[<eventmap>].event<indices>=[event]
>
> where <indices> is something like [0,3...5] or [all]
> (add -v to see detail)
> Run 'perf list' for a list of valid events
>
> Usage: perf record [<options>] [<command>]
> or: perf record [<options>] -- <command> [<options>]
>
> -e, --event <event> event selector. use 'perf list' to list available events
>
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Zefan Li <lizefan@huawei.com>
> Cc: pi3orama@163.com
> ---
> tools/perf/util/parse-events.c | 5 ++-
> tools/perf/util/parse-events.l | 13 ++++++-
> tools/perf/util/parse-events.y | 85 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 100 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index af3d657..abdf551 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -660,9 +660,10 @@ parse_events_config_bpf(struct parse_events_evlist *data,
> sizeof(errbuf));
> data->error->help = strdup(
> "Hint:\tValid config terms:\n"
> -" \tmaps:[<arraymap>].value=[value]\n"
> -" \tmaps:[<eventmap>].event=[event]\n"
> +" \tmaps:[<arraymap>].value<indices>=[value]\n"
> +" \tmaps:[<eventmap>].event<indices>=[event]\n"
> "\n"
> +" \twhere <indices> is something like [0,3...5] or [all]\n"
> " \t(add -v to see detail)");
> data->error->str = strdup(errbuf);
> if (err == -BPF_LOADER_ERRNO__OBJCONF_MAP_VALUE)
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 4387728..8bb3437 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -9,8 +9,8 @@
> %{
> #include <errno.h>
> #include "../perf.h"
> -#include "parse-events-bison.h"
> #include "parse-events.h"
> +#include "parse-events-bison.h"
>
> char *parse_events_get_text(yyscan_t yyscanner);
> YYSTYPE *parse_events_get_lval(yyscan_t yyscanner);
> @@ -111,6 +111,7 @@ do { \
> %x mem
> %s config
> %x event
> +%x array
>
> group [^,{}/]*[{][^}]*[}][^,{}/]*
> event_pmu [^,{}/]+[/][^/]*[/][^,{}/]*
> @@ -176,6 +177,14 @@ modifier_bp [rwx]{1,3}
>
> }
>
> +<array>{
> +"]" { BEGIN(config); return ']'; }
> +{num_dec} { return value(yyscanner, 10); }
> +{num_hex} { return value(yyscanner, 16); }
> +, { return ','; }
> +"\.\.\." { return PE_ARRAY_RANGE; }
> +}
> +
> <config>{
> /*
> * Please update parse_events_formats_error_string any time
> @@ -196,6 +205,8 @@ no-inherit { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_NOINHERIT); }
> , { return ','; }
> "/" { BEGIN(INITIAL); return '/'; }
> {name_minus} { return str(yyscanner, PE_NAME); }
> +\[all\] { return PE_ARRAY_ALL; }
> +"[" { BEGIN(array); return '['; }
> }
>
> <mem>{
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index c3cbd7a..7e93b9f 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -48,6 +48,7 @@ static inc_group_count(struct list_head *list,
> %token PE_PREFIX_MEM PE_PREFIX_RAW PE_PREFIX_GROUP
> %token PE_ERROR
> %token PE_PMU_EVENT_PRE PE_PMU_EVENT_SUF PE_KERNEL_PMU_EVENT
> +%token PE_ARRAY_ALL PE_ARRAY_RANGE
> %type <num> PE_VALUE
> %type <num> PE_VALUE_SYM_HW
> %type <num> PE_VALUE_SYM_SW
> @@ -84,6 +85,9 @@ static inc_group_count(struct list_head *list,
> %type group_def
> %type group
> %type groups
> +%type <array> array
> +%type <array> array_term
> +%type <array> array_terms
>
> %union
> {
> @@ -95,6 +99,7 @@ static inc_group_count(struct list_head *list,
> char *sys;
> char *event;
> } tracepoint_name;
> + struct parse_events_array array;
> }
> %%
>
> @@ -601,6 +606,86 @@ PE_TERM
> ABORT_ON(parse_events_term__num(&term, (int)$1, NULL, 1, &@1, NULL));
> $$ = term;
> }
> +|
> +PE_NAME array '=' PE_NAME
> +{
> + struct parse_events_term *term;
> + int i;
> +
> + ABORT_ON(parse_events_term__str(&term, PARSE_EVENTS__TERM_TYPE_USER,
> + $1, $4, &@1, &@4));
> +
> + term->array = $2;
> + $$ = term;
> +}
> +|
> +PE_NAME array '=' PE_VALUE
> +{
> + struct parse_events_term *term;
> +
> + ABORT_ON(parse_events_term__num(&term, PARSE_EVENTS__TERM_TYPE_USER,
> + $1, $4, &@1, &@4));
> + term->array = $2;
> + $$ = term;
> +}
> +
> +array:
> +'[' array_terms ']'
> +{
> + $$ = $2;
> +}
> +|
> +PE_ARRAY_ALL
> +{
> + $$.nr_ranges = 0;
> + $$.ranges = NULL;
> +}
> +
> +array_terms:
> +array_terms ',' array_term
> +{
> + struct parse_events_array new_array;
> +
> + new_array.nr_ranges = $1.nr_ranges + $3.nr_ranges;
> + new_array.ranges = malloc(sizeof(new_array.ranges[0]) *
> + new_array.nr_ranges);
> + ABORT_ON(!new_array.ranges);
> + memcpy(&new_array.ranges[0], $1.ranges,
> + $1.nr_ranges * sizeof(new_array.ranges[0]));
> + memcpy(&new_array.ranges[$1.nr_ranges], $3.ranges,
> + $3.nr_ranges * sizeof(new_array.ranges[0]));
> + free($1.ranges);
> + free($3.ranges);
> + $$ = new_array;
> +}
> +|
> +array_term
> +
> +array_term:
> +PE_VALUE
> +{
> + struct parse_events_array array;
> +
> + array.nr_ranges = 1;
> + array.ranges = malloc(sizeof(array.ranges[0]));
> + ABORT_ON(!array.ranges);
> + array.ranges[0].start = $1;
> + array.ranges[0].length = 1;
> + $$ = array;
> +}
> +|
> +PE_VALUE PE_ARRAY_RANGE PE_VALUE
> +{
> + struct parse_events_array array;
> +
> + ABORT_ON($3 < $1);
> + array.nr_ranges = 1;
> + array.ranges = malloc(sizeof(array.ranges[0]));
> + ABORT_ON(!array.ranges);
> + array.ranges[0].start = $1;
> + array.ranges[0].length = $3 - $1 + 1;
> + $$ = array;
> +}
>
> sep_dc: ':' |
>
> --
> 1.8.3.4