On Mon, 4 Mar 2024 19:13:42 -0500 Steven Rostedt <rost...@goodmis.org> wrote:
> From: "Steven Rostedt (Google)" <rost...@goodmis.org> > > The trace_seq buffer is used to print out entire events. It's typically > set to PAGE_SIZE * 2 as there's some events that can be quite large. > > As a side effect, writes to trace_marker is limited by both the size of the > trace_seq buffer as well as the ring buffer's sub-buffer size (which is a > power of PAGE_SIZE). By limiting the trace_seq size, it also limits the > size of the largest string written to trace_marker. > > trace_seq does not need to be dependent on PAGE_SIZE like the ring buffer > sub-buffers need to be. Hard code it to 8K which is PAGE_SIZE * 2 on most > architectures. This will also limit the size of trace_marker on those > architectures with greater than 4K PAGE_SIZE. > > Link: https://lore.kernel.org/all/20240302111244.3a167...@gandalf.local.home/ > 8K is reasonably enough big. Looks good to me. Acked-by: Masami Hiramatsu (Google) <mhira...@kernel.org> Thank you, > Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org> > --- > include/linux/trace_seq.h | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h > index 9ec229dfddaa..1ef95c0287f0 100644 > --- a/include/linux/trace_seq.h > +++ b/include/linux/trace_seq.h > @@ -9,9 +9,15 @@ > /* > * Trace sequences are used to allow a function to call several other > functions > * to create a string of data to use. > + * > + * Have the trace seq to be 8K which is typically PAGE_SIZE * 2 on > + * most architectures. The TRACE_SEQ_BUFFER_SIZE (which is > + * TRACE_SEQ_SIZE minus the other fields of trace_seq), is the > + * max size the output of a trace event may be. > */ > > -#define TRACE_SEQ_BUFFER_SIZE (PAGE_SIZE * 2 - \ > +#define TRACE_SEQ_SIZE 8192 > +#define TRACE_SEQ_BUFFER_SIZE (TRACE_SEQ_SIZE - \ > (sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int))) > > struct trace_seq { > -- > 2.43.0 > -- Masami Hiramatsu (Google) <mhira...@kernel.org>
