Re: [PATCH 02/17] perf tools: Add evlist channel helpers

From: Arnaldo Carvalho de Melo
Date: Fri May 13 2016 - 09:05:33 EST

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In reply to: Wang Nan: "[PATCH 02/17] perf tools: Add evlist channel helpers"
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Em Fri, May 13, 2016 at 07:55:59AM +0000, Wang Nan escreveu:
> In this commit sereval helpers are introduced to support the principle

several

> of channel. Channels hold different groups of evsels which configured
> differently. It will be used for overwritable evsels, which allows perf

why not use multiple evlists? An "evlist" is a "list of evsels", why do
we need yet another way of grouping evlists?

- Arnaldo

> record some events continuously while capture snapshot for other events
> when something happen. Tracking events (mmap, mmap2, fork, exit ...)
> are another possible events worth to be put into a separated channel.
>
> Channels are represented by an array with channel flags. Each channel
> contains evlist->nr_mmaps mmaps. Channels are configured before
> perf_evlist__mmap_ex(). During that function nr_mmaps mmaps for each
> channel are allocated together as a big array.
> perf_evlist__channel_idx() converts index in the big array and the
> channel number. For API functions which accept idx, _ex() versions are
> introduced to accept selecting an mmap from a channel.
>
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Zefan Li <lizefan@xxxxxxxxxx>
> Cc: pi3orama@xxxxxxx
> ---
> tools/perf/builtin-record.c | 6 ++
> tools/perf/util/evlist.c | 130 ++++++++++++++++++++++++++++++++++++++++++--
> tools/perf/util/evlist.h | 58 ++++++++++++++++++++
> 3 files changed, 188 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index f3679c4..6e44834 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -316,6 +316,12 @@ try_again:
> goto out;
> }
>
> + perf_evlist__channel_reset(evlist);
> + rc = perf_evlist__channel_add(evlist, 0, true);
> + if (rc < 0)
> + goto out;
> + rc = 0;
> +
> if (perf_evlist__mmap_ex(evlist, opts->mmap_pages, false,
> opts->auxtrace_mmap_pages,
> opts->auxtrace_snapshot_mode) < 0) {
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 5e86972..6c11b9e 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -679,6 +679,33 @@ static struct perf_evsel *perf_evlist__event2evsel(struct perf_evlist *evlist,
> return NULL;
> }
>
> +int perf_evlist__channel_idx(struct perf_evlist *evlist,
> + int *p_channel, int *p_idx)
> +{
> + int channel = *p_channel;
> + int _idx = *p_idx;
> +
> + if (_idx < 0)
> + return -EINVAL;
> + /*
> + * Negative channel means caller explicitly use real index.
> + */
> + if (channel < 0) {
> + channel = perf_evlist__idx_channel(evlist, _idx);
> + _idx = _idx % evlist->nr_mmaps;
> + }
> + if (channel < 0)
> + return channel;
> + if (channel >= PERF_EVLIST__NR_CHANNELS)
> + return -E2BIG;
> + if (_idx >= evlist->nr_mmaps)
> + return -E2BIG;
> +
> + *p_channel = channel;
> + *p_idx = evlist->nr_mmaps * channel + _idx;
> + return 0;
> +}
> +
> /* When check_messup is true, 'end' must points to a good entry */
> static union perf_event *
> perf_mmap__read(struct perf_mmap *md, bool check_messup, u64 start,
> @@ -756,11 +783,19 @@ __perf_evlist__mmap_read(struct perf_mmap *md, bool overwrite, u64 head,
> return perf_mmap__read(md, overwrite, old, head, prev);
> }
>
> -union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
> +union perf_event *perf_evlist__mmap_read_ex(struct perf_evlist *evlist,
> + int channel, int idx)
> {
> struct perf_mmap *md = &evlist->mmap[idx];
> - u64 head;
> - u64 old = md->prev;
> + u64 head, old;
> + int err = perf_evlist__channel_idx(evlist, &channel, &idx);
> +
> + if (err || !perf_evlist__channel_is_enabled(evlist, channel)) {
> + pr_err("ERROR: invalid mmap index: channel %d, idx: %d\n",
> + channel, idx);
> + return NULL;
> + }
> + old = md->prev;
>
> /*
> * Check if event was unmapped due to a POLLHUP/POLLERR.
> @@ -824,6 +859,11 @@ void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx)
> md->prev = head;
> }
>
> +union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
> +{
> + return perf_evlist__mmap_read_ex(evlist, -1, idx);
> +}
> +
> static bool perf_mmap__empty(struct perf_mmap *md)
> {
> return perf_mmap__read_head(md) == md->prev && !md->auxtrace_mmap.base;
> @@ -842,10 +882,18 @@ static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
> __perf_evlist__munmap(evlist, idx);
> }
>
> -void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
> +void perf_evlist__mmap_consume_ex(struct perf_evlist *evlist,
> + int channel, int idx)
> {
> + int err = perf_evlist__channel_idx(evlist, &channel, &idx);
> struct perf_mmap *md = &evlist->mmap[idx];
>
> + if (err || !perf_evlist__channel_is_enabled(evlist, channel)) {
> + pr_err("ERROR: invalid mmap index: channel %d, idx: %d\n",
> + channel, idx);
> + return;
> + }
> +
> if (!evlist->overwrite) {
> u64 old = md->prev;
>
> @@ -856,6 +904,11 @@ void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
> perf_evlist__mmap_put(evlist, idx);
> }
>
> +void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
> +{
> + perf_evlist__mmap_consume_ex(evlist, -1, idx);
> +}
> +
> int __weak auxtrace_mmap__mmap(struct auxtrace_mmap *mm __maybe_unused,
> struct auxtrace_mmap_params *mp __maybe_unused,
> void *userpg __maybe_unused,
> @@ -901,7 +954,7 @@ void perf_evlist__munmap(struct perf_evlist *evlist)
> if (evlist->mmap == NULL)
> return;
>
> - for (i = 0; i < evlist->nr_mmaps; i++)
> + for (i = 0; i < perf_evlist__mmap_nr(evlist); i++)
> __perf_evlist__munmap(evlist, i);
>
> zfree(&evlist->mmap);
> @@ -909,10 +962,17 @@ void perf_evlist__munmap(struct perf_evlist *evlist)
>
> static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
> {
> + int total_mmaps;
> +
> evlist->nr_mmaps = cpu_map__nr(evlist->cpus);
> if (cpu_map__empty(evlist->cpus))
> evlist->nr_mmaps = thread_map__nr(evlist->threads);
> - evlist->mmap = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
> +
> + total_mmaps = perf_evlist__mmap_nr(evlist);
> + if (!total_mmaps)
> + return -EINVAL;
> +
> + evlist->mmap = zalloc(total_mmaps * sizeof(struct perf_mmap));
> return evlist->mmap != NULL ? 0 : -ENOMEM;
> }
>
> @@ -1221,6 +1281,12 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
> int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
> bool overwrite)
> {
> + int err;
> +
> + perf_evlist__channel_reset(evlist);
> + err = perf_evlist__channel_add(evlist, 0, true);
> + if (err < 0)
> + return err;
> return perf_evlist__mmap_ex(evlist, pages, overwrite, 0, false);
> }
>
> @@ -1862,3 +1928,55 @@ perf_evlist__find_evsel_by_str(struct perf_evlist *evlist,
>
> return NULL;
> }
> +
> +int perf_evlist__channel_nr(struct perf_evlist *evlist)
> +{
> + int i;
> +
> + for (i = PERF_EVLIST__NR_CHANNELS - 1; i >= 0; i--) {
> + unsigned long flags = evlist->channel_flags[i];
> +
> + if (flags & PERF_EVLIST__CHANNEL_ENABLED)
> + return i + 1;
> + }
> + return 0;
> +}
> +
> +int perf_evlist__mmap_nr(struct perf_evlist *evlist)
> +{
> + return evlist->nr_mmaps * perf_evlist__channel_nr(evlist);
> +}
> +
> +void perf_evlist__channel_reset(struct perf_evlist *evlist)
> +{
> + int i;
> +
> + BUG_ON(evlist->mmap);
> +
> + for (i = 0; i < PERF_EVLIST__NR_CHANNELS; i++)
> + evlist->channel_flags[i] = 0;
> +}
> +
> +int perf_evlist__channel_add(struct perf_evlist *evlist,
> + unsigned long flag,
> + bool is_default)
> +{
> + int n = perf_evlist__channel_nr(evlist);
> + unsigned long *flags = evlist->channel_flags;
> +
> + BUG_ON(evlist->mmap);
> +
> + if (n >= PERF_EVLIST__NR_CHANNELS) {
> + pr_debug("ERROR: too many channels. Increase PERF_EVLIST__NR_CHANNELS\n");
> + return -ENOSPC;
> + }
> +
> + if (is_default) {
> + memmove(&flags[1], &flags[0],
> + sizeof(evlist->channel_flags) -
> + sizeof(evlist->channel_flags[0]));
> + n = 0;
> + }
> + flags[n] = flag | PERF_EVLIST__CHANNEL_ENABLED;
> + return n;
> +}
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index 85d1b59..4cb5d3a 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -20,6 +20,11 @@ struct record_opts;
> #define PERF_EVLIST__HLIST_BITS 8
> #define PERF_EVLIST__HLIST_SIZE (1 << PERF_EVLIST__HLIST_BITS)
>
> +#define PERF_EVLIST__NR_CHANNELS 1
> +enum perf_evlist_mmap_flag {
> + PERF_EVLIST__CHANNEL_ENABLED = 1,
> +};
> +
> /**
> * struct perf_mmap - perf's ring buffer mmap details
> *
> @@ -52,6 +57,7 @@ struct perf_evlist {
> pid_t pid;
> } workload;
> struct fdarray pollfd;
> + unsigned long channel_flags[PERF_EVLIST__NR_CHANNELS];
> struct perf_mmap *mmap;
> struct thread_map *threads;
> struct cpu_map *cpus;
> @@ -127,13 +133,65 @@ struct perf_evsel *perf_evlist__id2evsel_strict(struct perf_evlist *evlist,
>
> struct perf_sample_id *perf_evlist__id2sid(struct perf_evlist *evlist, u64 id);
>
> +union perf_event *perf_evlist__mmap_read_ex(struct perf_evlist *evlist,
> + int channel, int idx);
> union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx);
>
> union perf_event *perf_evlist__mmap_read_backward(struct perf_evlist *evlist,
> int idx);
> void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx);
>
> +void perf_evlist__mmap_consume_ex(struct perf_evlist *evlist,
> + int channel, int idx);
> void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx);
> +int perf_evlist__mmap_nr(struct perf_evlist *evlist);
> +
> +int perf_evlist__channel_nr(struct perf_evlist *evlist);
> +void perf_evlist__channel_reset(struct perf_evlist *evlist);
> +int perf_evlist__channel_add(struct perf_evlist *evlist,
> + unsigned long flag,
> + bool is_default);
> +
> +static inline bool
> +__perf_evlist__channel_check(struct perf_evlist *evlist, int channel,
> + enum perf_evlist_mmap_flag bits)
> +{
> + if (channel >= PERF_EVLIST__NR_CHANNELS)
> + return false;
> +
> + return (evlist->channel_flags[channel] & bits) ? true : false;
> +}
> +#define perf_evlist__channel_check(e, c, b) \
> + __perf_evlist__channel_check(e, c, PERF_EVLIST__CHANNEL_##b)
> +
> +static inline bool
> +perf_evlist__channel_is_enabled(struct perf_evlist *evlist, int channel)
> +{
> + return perf_evlist__channel_check(evlist, channel, ENABLED);
> +}
> +
> +static inline int
> +perf_evlist__idx_channel(struct perf_evlist *evlist, int idx)
> +{
> + int channel = idx / evlist->nr_mmaps;
> +
> + if (channel >= PERF_EVLIST__NR_CHANNELS)
> + return -E2BIG;
> + return channel;
> +}
> +
> +int perf_evlist__channel_idx(struct perf_evlist *evlist,
> + int *p_channel, int *p_idx);
> +
> +static inline struct perf_mmap *
> +perf_evlist__get_mmap(struct perf_evlist *evlist,
> + int channel, int idx)
> +{
> + if (perf_evlist__channel_idx(evlist, &channel, &idx))
> + return NULL;
> +
> + return &evlist->mmap[idx];
> +}
>
> int perf_evlist__open(struct perf_evlist *evlist);
> void perf_evlist__close(struct perf_evlist *evlist);
> --
> 1.8.3.4

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Previous message: Arnaldo Carvalho de Melo: "Re: [PATCH 01/17] perf tools: Extract __perf_evlist__mmap_read()"
In reply to: Wang Nan: "[PATCH 02/17] perf tools: Add evlist channel helpers"
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