| Message ID | 20200409132825.79475-3-tz.stoyanov@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | Split reading the trace.dat options from trace data | expand |
On Thu, 9 Apr 2020 16:28:25 +0300 "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote: > Add an API to create a tracecmd_handle from a file, > read and parse only the trace headers from the file. > This allows to implement opening a trace file on > stages - reading the trace headers and reading the trace data. > > Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com> > --- > include/trace-cmd/trace-cmd.h | 1 + > lib/trace-cmd/trace-input.c | 28 ++++++++++++++++++++++++++++ > 2 files changed, 29 insertions(+) > > diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h > index 3f96bbde..e22aa251 100644 > --- a/include/trace-cmd/trace-cmd.h > +++ b/include/trace-cmd/trace-cmd.h > @@ -143,6 +143,7 @@ typedef void (*tracecmd_handle_init_func)(struct tracecmd_input *handle, > struct tracecmd_input *tracecmd_alloc(const char *file); > struct tracecmd_input *tracecmd_alloc_fd(int fd); > struct tracecmd_input *tracecmd_open(const char *file); > +struct tracecmd_input *tracecmd_open_head(const char *file); > struct tracecmd_input *tracecmd_open_fd(int fd); > void tracecmd_ref(struct tracecmd_input *handle); > void tracecmd_close(struct tracecmd_input *handle); Hi Tzvetomir, I was thinking, before we release libtracecmd, we should add tracecmd_open() and tracecmd_open_fd() to the library. Just because I find that tracecmd_open_head() is a awkward name to have alone and only makes sense if there's already a tracecmd_open(). It will also help with differentiating the different functions. I know we were going to only have functions that kernelshark uses, but that may be a little too limiting. Thanks! -- Steve
On Thu, Jan 14, 2021 at 12:01 AM Steven Rostedt <rostedt@goodmis.org> wrote: > > On Thu, 9 Apr 2020 16:28:25 +0300 > "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote: > > > Add an API to create a tracecmd_handle from a file, > > read and parse only the trace headers from the file. > > This allows to implement opening a trace file on > > stages - reading the trace headers and reading the trace data. > > > > Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com> > > --- > > include/trace-cmd/trace-cmd.h | 1 + > > lib/trace-cmd/trace-input.c | 28 ++++++++++++++++++++++++++++ > > 2 files changed, 29 insertions(+) > > > > diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h > > index 3f96bbde..e22aa251 100644 > > --- a/include/trace-cmd/trace-cmd.h > > +++ b/include/trace-cmd/trace-cmd.h > > @@ -143,6 +143,7 @@ typedef void (*tracecmd_handle_init_func)(struct tracecmd_input *handle, > > struct tracecmd_input *tracecmd_alloc(const char *file); > > struct tracecmd_input *tracecmd_alloc_fd(int fd); > > struct tracecmd_input *tracecmd_open(const char *file); > > +struct tracecmd_input *tracecmd_open_head(const char *file); > > struct tracecmd_input *tracecmd_open_fd(int fd); > > void tracecmd_ref(struct tracecmd_input *handle); > > void tracecmd_close(struct tracecmd_input *handle); > > Hi Tzvetomir, > > I was thinking, before we release libtracecmd, we should add > tracecmd_open() and tracecmd_open_fd() to the library. Just because I find > that tracecmd_open_head() is a awkward name to have alone and only makes > sense if there's already a tracecmd_open(). It will also help with > differentiating the different functions. I'll add tracecmd_open() and tracecmd_open_fd() as APIs. The reason why tracecmd_open_head() is used by KernelShark is that tracecmd_open() reads headers + tracing data and calculates the timestamps. Thus makes it hard to open multiple tracing files from a single trace session and adjust timestamps to be in a same time space. The current KernelShark open flow is: - Open a trace file and parse only the headers with tracecmd_open_head() - Based on the metadata information from the headers, check if there is already an opened file from the same tracing session. If such is found, pair both files with tracecmd_pair_peer(), before reading the tracing data. - Read the tracing data from the file with tracecmd_init_data(). This will adjust timestamps accordingly, if there is a paired peer to the file. We can rename tracecmd_open_head() to something else, or redesign the whole flow of opening trace files > > I know we were going to only have functions that kernelshark uses, but that > may be a little too limiting. > > Thanks! > > -- Steve
diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h index 3f96bbde..e22aa251 100644 --- a/include/trace-cmd/trace-cmd.h +++ b/include/trace-cmd/trace-cmd.h @@ -143,6 +143,7 @@ typedef void (*tracecmd_handle_init_func)(struct tracecmd_input *handle, struct tracecmd_input *tracecmd_alloc(const char *file); struct tracecmd_input *tracecmd_alloc_fd(int fd); struct tracecmd_input *tracecmd_open(const char *file); +struct tracecmd_input *tracecmd_open_head(const char *file); struct tracecmd_input *tracecmd_open_fd(int fd); void tracecmd_ref(struct tracecmd_input *handle); void tracecmd_close(struct tracecmd_input *handle); diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c index ee9bfb52..efc8d4bd 100644 --- a/lib/trace-cmd/trace-input.c +++ b/lib/trace-cmd/trace-input.c @@ -3175,6 +3175,34 @@ struct tracecmd_input *tracecmd_open(const char *file) return tracecmd_open_fd(fd); } +/** + * tracecmd_open_head - create a tracecmd_handle from a given file, read + * read and parse only the trace headers from the file + * @file: the file name of the file that is of tracecmd data type. + */ +struct tracecmd_input *tracecmd_open_head(const char *file) +{ + struct tracecmd_input *handle; + int fd; + + fd = open(file, O_RDONLY); + if (fd < 0) + return NULL; + + handle = tracecmd_alloc_fd(fd); + if (!handle) + return NULL; + + if (tracecmd_read_headers(handle) < 0) + goto fail; + + return handle; + +fail: + tracecmd_close(handle); + return NULL; +} + /** * tracecmd_ref - add a reference to the handle * @handle: input handle for the trace.dat file
Add an API to create a tracecmd_handle from a file, read and parse only the trace headers from the file. This allows to implement opening a trace file on stages - reading the trace headers and reading the trace data. Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com> --- include/trace-cmd/trace-cmd.h | 1 + lib/trace-cmd/trace-input.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+)