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Message-ID: <Yo4Wpqzwp+XmfkMV@kernel.org>
Date: Wed, 25 May 2022 08:44:38 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Andi Kleen <ak@...ux.intel.com>,
Song Liu <songliubraving@...com>, Hao Luo <haoluo@...gle.com>,
Milian Wolff <milian.wolff@...b.com>,
bpf <bpf@...r.kernel.org>,
linux-perf-users <linux-perf-users@...r.kernel.org>,
Blake Jones <blakejones@...gle.com>
Subject: Re: [PATCH 3/6] perf record: Implement basic filtering for off-cpu
Em Wed, May 25, 2022 at 08:27:38AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, May 19, 2022 at 02:02:28PM -0700, Namhyung Kim escreveu:
> > On Wed, May 18, 2022 at 9:02 PM Ian Rogers <irogers@...gle.com> wrote:
> > >
> > > On Wed, May 18, 2022 at 3:47 PM Namhyung Kim <namhyung@...nel.org> wrote:
> > > >
> > > > It should honor cpu and task filtering with -a, -C or -p, -t options.
> > > >
> > > > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > > > ---
> > > > tools/perf/builtin-record.c | 2 +-
> > > > tools/perf/util/bpf_off_cpu.c | 78 +++++++++++++++++++++++---
> > > > tools/perf/util/bpf_skel/off_cpu.bpf.c | 52 +++++++++++++++--
> > > > tools/perf/util/off_cpu.h | 6 +-
> > > > 4 files changed, 123 insertions(+), 15 deletions(-)
> > > >
> > > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > > > index 91f88501412e..7f60d2eac0b4 100644
> > > > --- a/tools/perf/builtin-record.c
> > > > +++ b/tools/perf/builtin-record.c
> > > > @@ -907,7 +907,7 @@ static int record__config_text_poke(struct evlist *evlist)
> > > >
> > > > static int record__config_off_cpu(struct record *rec)
> > > > {
> > > > - return off_cpu_prepare(rec->evlist);
> > > > + return off_cpu_prepare(rec->evlist, &rec->opts.target);
> > > > }
> > > >
> > > > static bool record__kcore_readable(struct machine *machine)
> > > > diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
> > > > index 9ed7aca3f4ac..b5e2d038da50 100644
> > > > --- a/tools/perf/util/bpf_off_cpu.c
> > > > +++ b/tools/perf/util/bpf_off_cpu.c
> > > > @@ -6,6 +6,9 @@
> > > > #include "util/off_cpu.h"
> > > > #include "util/perf-hooks.h"
> > > > #include "util/session.h"
> > > > +#include "util/target.h"
> > > > +#include "util/cpumap.h"
> > > > +#include "util/thread_map.h"
> > > > #include <bpf/bpf.h>
> > > >
> > > > #include "bpf_skel/off_cpu.skel.h"
> > > > @@ -60,8 +63,23 @@ static int off_cpu_config(struct evlist *evlist)
> > > > return 0;
> > > > }
> > > >
> > > > -static void off_cpu_start(void *arg __maybe_unused)
> > > > +static void off_cpu_start(void *arg)
> > > > {
> > > > + struct evlist *evlist = arg;
> > > > +
> > > > + /* update task filter for the given workload */
> > > > + if (!skel->bss->has_cpu && !skel->bss->has_task &&
> > > > + perf_thread_map__pid(evlist->core.threads, 0) != -1) {
> > > > + int fd;
> > > > + u32 pid;
> > > > + u8 val = 1;
> > > > +
> > > > + skel->bss->has_task = 1;
> > > > + fd = bpf_map__fd(skel->maps.task_filter);
> > > > + pid = perf_thread_map__pid(evlist->core.threads, 0);
> > > > + bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
> > > > + }
> > > > +
> > > > skel->bss->enabled = 1;
> > > > }
> > > >
> > > > @@ -71,31 +89,75 @@ static void off_cpu_finish(void *arg __maybe_unused)
> > > > off_cpu_bpf__destroy(skel);
> > > > }
> > > >
> > > > -int off_cpu_prepare(struct evlist *evlist)
> > > > +int off_cpu_prepare(struct evlist *evlist, struct target *target)
> > > > {
> > > > - int err;
> > > > + int err, fd, i;
> > > > + int ncpus = 1, ntasks = 1;
> > > >
> > > > if (off_cpu_config(evlist) < 0) {
> > > > pr_err("Failed to config off-cpu BPF event\n");
> > > > return -1;
> > > > }
> > > >
> > > > - set_max_rlimit();
> > > > -
> > > > - skel = off_cpu_bpf__open_and_load();
> > > > + skel = off_cpu_bpf__open();
> > > > if (!skel) {
> > > > pr_err("Failed to open off-cpu BPF skeleton\n");
> > > > return -1;
> > > > }
> > > >
> > > > + /* don't need to set cpu filter for system-wide mode */
> > > > + if (target->cpu_list) {
> > > > + ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
> > > > + bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
> > > > + }
> > > > +
> > > > + if (target__has_task(target)) {
> > > > + ntasks = perf_thread_map__nr(evlist->core.threads);
> > > > + bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
> > > > + }
> > > > +
> > > > + set_max_rlimit();
> > > > +
> > > > + err = off_cpu_bpf__load(skel);
> > > > + if (err) {
> > > > + pr_err("Failed to load off-cpu skeleton\n");
> > > > + goto out;
> > > > + }
> > > > +
> > > > + if (target->cpu_list) {
> > > > + u32 cpu;
> > > > + u8 val = 1;
> > > > +
> > > > + skel->bss->has_cpu = 1;
> > > > + fd = bpf_map__fd(skel->maps.cpu_filter);
> > > > +
> > > > + for (i = 0; i < ncpus; i++) {
> > > > + cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
> > > > + bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
> > >
> > > Perhaps more concise with a for_each:
> > >
> > > perf_cpu_map__for_each_cpu(cpu, idx, evlist->core.user_requested_cpus)
> > > bpf_map_update_elem(fd, &cpu.cpu, &val, BPF_ANY);
>
> So I'll wait for a new version of this patchset.
I take that back, will apply and this can be a follow up patch, right?
- Arnaldo
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