Hi, On 28.08.2018 11:50, Jiri Olsa wrote: > On Mon, Aug 27, 2018 at 09:16:55PM +0300, Alexey Budankov wrote: >> >> Trace file offset are linearly calculated by perf_mmap__push() code >> for the next possible write operation, but file position is updated by >> the kernel only in the second lseek() syscall after the loop. >> The first lseek() syscall reads that file position for >> the next loop iterations. >> >> record__mmap_read_sync implements sort of a barrier between spilling >> ready profiling data to disk. >> >> Signed-off-by: Alexey Budankov <[email protected]> >> --- >> Changes in v3: >> - written comments about nanosleep(0.5ms) call prior aio_suspend() >> to cope with intrusiveness of its implementation in glibc; >> - written comments about rationale behind coping profiling data >> into mmap->data buffer; >> --- >> tools/perf/builtin-record.c | 125 >> +++++++++++++++++++++++++++++++++++++++++--- >> tools/perf/util/mmap.c | 36 ++++++++----- >> tools/perf/util/mmap.h | 2 +- >> 3 files changed, 143 insertions(+), 20 deletions(-) >> >> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c >> index 22ebeb92ac51..4ac61399a09a 100644 >> --- a/tools/perf/builtin-record.c >> +++ b/tools/perf/builtin-record.c >> @@ -53,6 +53,7 @@ >> #include <sys/mman.h> >> #include <sys/wait.h> >> #include <linux/time64.h> >> +#include <aio.h> >> >> struct switch_output { >> bool enabled; >> @@ -121,6 +122,23 @@ static int record__write(struct record *rec, void *bf, >> size_t size) >> return 0; >> } >> >> +static int record__aio_write(int trace_fd, struct aiocb *cblock, >> + void *buf, size_t size, off_t off) >> +{ >> + cblock->aio_fildes = trace_fd; >> + cblock->aio_buf = buf; >> + cblock->aio_nbytes = size; >> + cblock->aio_offset = off; >> + cblock->aio_sigevent.sigev_notify = SIGEV_NONE; >> + >> + if (aio_write(cblock) == -1) { >> + pr_err("failed to queue perf data, error: %m\n"); >> + return -1; >> + } >> + >> + return 0; >> +} >> + >> static int process_synthesized_event(struct perf_tool *tool, >> union perf_event *event, >> struct perf_sample *sample __maybe_unused, >> @@ -130,12 +148,14 @@ static int process_synthesized_event(struct perf_tool >> *tool, >> return record__write(rec, event, event->header.size); >> } >> >> -static int record__pushfn(void *to, void *bf, size_t size) >> +static int record__pushfn(void *to, void *bf, size_t size, off_t off) >> { >> struct record *rec = to; >> + struct perf_mmap *map = bf; > > the argument needs to change for record__pushfn, > now with your changes, it's no longer 'void *bf', > but 'struct perf_mmap *map'
Ok. Included into [PATCH v4 2/2]. > > also I'm little confused why we have '*to' and cast > it back to 'struct record', but so be it ;-) Supported. :) > > thanks, > jirka >
