Hi Adrian, On Tue, May 19, 2015 at 04:05:46PM +0300, Adrian Hunter wrote: > Patch "perf tools: Protect dso cache fd with a mutex" > changed data_file_size() to open the data file if it > was not open. > > data_read_offset() was calling data_file_size() to read > the data file size, but data_file_size() can fail to > open the file because the binary_type has not been set up. > > The correct function to call is dso__data_size() which > uses dso__data_fd() to open the file correctly.
Right, but I worried about the locking overhead. By using dso__data_size() it'll call dso__data_fd() everytime which grabs the dso__data_open_lock that is a global mutex. It can be a performance bottleneck on multi-thread report IMHO. I assumed that correct code should check the data fd or size before calling read function as I read the comment in dso.h file. What about adding the missing check in a proper place instead? Thanks, Namhyung > > Signed-off-by: Adrian Hunter <[email protected]> > --- > tools/perf/util/dso.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c > index 1b96c8d..e248f56 100644 > --- a/tools/perf/util/dso.c > +++ b/tools/perf/util/dso.c > @@ -756,7 +756,7 @@ off_t dso__data_size(struct dso *dso, struct machine > *machine) > static ssize_t data_read_offset(struct dso *dso, struct machine *machine, > u64 offset, u8 *data, ssize_t size) > { > - if (data_file_size(dso, machine)) > + if (dso__data_size(dso, machine) < 0) > return -1; > > /* Check the offset sanity. */ > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
