Messages in this thread | | | Date | Sat, 23 Jan 2021 23:42:13 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH v5 4/9] libperf: Add evsel mmap support |
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On Wed, Jan 13, 2021 at 08:06:00PM -0600, Rob Herring wrote: > In order to support usersapce access, an event must be mmapped. While > there's already mmap support for evlist, the usecase is a bit different > than the self monitoring with userspace access. So let's add a new > perf_evsel__mmap() function to mmap an evsel. This allows implementing > userspace access as a fastpath for perf_evsel__read(). > > The mmapped address is returned by perf_evsel__mmap_base() which > primarily for users/tests to check if userspace access is enabled. > > Signed-off-by: Rob Herring <robh@kernel.org> > --- > v5: > - Create an mmap for every underlying event opened. Due to this, we > need a different way to get the mmap ptr, so perf_evsel__mmap_base() > is introduced. > v4: > - Change perf_evsel__mmap size to pages instead of bytes > v3: > - New patch split out from user access patch > --- > tools/lib/perf/Documentation/libperf.txt | 2 + > tools/lib/perf/evsel.c | 47 +++++++++++++++++++++++- > tools/lib/perf/include/internal/evsel.h | 2 + > tools/lib/perf/include/perf/evsel.h | 2 + > tools/lib/perf/libperf.map | 2 + > 5 files changed, 53 insertions(+), 2 deletions(-) > > diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt > index 0c74c30ed23a..a2c73df191ca 100644 > --- a/tools/lib/perf/Documentation/libperf.txt > +++ b/tools/lib/perf/Documentation/libperf.txt > @@ -136,6 +136,8 @@ SYNOPSIS > struct perf_thread_map *threads); > void perf_evsel__close(struct perf_evsel *evsel); > void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu); > + int perf_evsel__mmap(struct perf_evsel *evsel, int pages); > + void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread); > int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread, > struct perf_counts_values *count); > int perf_evsel__enable(struct perf_evsel *evsel); > diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c > index 4dc06289f4c7..0b5bdf4badae 100644 > --- a/tools/lib/perf/evsel.c > +++ b/tools/lib/perf/evsel.c > @@ -11,10 +11,12 @@ > #include <stdlib.h> > #include <internal/xyarray.h> > #include <internal/cpumap.h> > +#include <internal/mmap.h> > #include <internal/threadmap.h> > #include <internal/lib.h> > #include <linux/string.h> > #include <sys/ioctl.h> > +#include <sys/mman.h> > > void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr) > { > @@ -37,11 +39,17 @@ void perf_evsel__delete(struct perf_evsel *evsel) > free(evsel); > } > > -#define FD(e, x, y) (*(int *) xyarray__entry(e->fd, x, y)) > +struct evsel_fd { > + int fd; > + struct perf_mmap mmap; > +};
nice shortcut ;-) but 'struct perf_mmap' is too big for that
I think it's better to add new 'evsel::mmap' xyarray to hold it, add perf_evsel__alloc_mmap to allocate it and call it from perf_evsel__mmap the same way as we callperf_evsel__alloc_fd from perf_evsel__open
thanks, jirka
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