Messages in this thread | | | Date | Mon, 13 Dec 2010 14:58:15 -0200 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header |
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Em Mon, Dec 13, 2010 at 11:15:57AM -0200, Arnaldo Carvalho de Melo escreveu: > Em Sun, Dec 12, 2010 at 09:16:16PM +0100, Frederic Weisbecker escreveu: > > On Tue, Dec 07, 2010 at 06:54:44PM -0700, David Ahern wrote: > > > +++ b/tools/perf/util/header.c > > > @@ -191,6 +191,40 @@ static int write_padded(int fd, const void *bf, size_t count, > > > +static int perf_header__read_ref_time(struct perf_header *header, > > > + int fd, u64 offset, u64 size) > > > +{ > > > + size_t sz_nsec = sizeof(header->nsec_ref); > > > + size_t sz_tv = sizeof(header->tv_ref); > > > + int err = -1; > > > + > > > + if (((size - offset) < (sz_nsec + sz_tv)) || > > > + (read(fd, &header->nsec_ref, sz_nsec) != (ssize_t) sz_nsec) || > > > + (read(fd, &header->tv_ref, sz_tv) != (ssize_t) sz_tv)) > > > + goto out; > > > > Hmm, could we have endianness related troubles if we write the timespec on > > an arch and cross read from another, or other cross read issues? > > Well spotted, it needs to use perf_header__getbuffer64 and make sure > that nsec_ref, etc are u64 fields.
When implemented as a PERF_RECORD_REF_TIME or PERF_RECORD_WALL_CLOCK this will be handled in perf_session__process_event, implementing a event__ref_time_swap routine, etc.
- Arnaldo
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