Messages in this thread | | | Date | Thu, 12 Jan 2023 16:24:17 -0700 | From | Ross Zwisler <> | Subject | Re: [PATCH 1/4] tracing: Add creation of instances at boot command line |
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On Wed, Jan 11, 2023 at 09:56:37AM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Add kernel command line to add tracing instances. This only creates > instances at boot but still does not enable any events to them. Later > changes will extend this command line to add enabling of events, filters, > and triggers. As well as possibly redirecting trace_printk()! > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > .../admin-guide/kernel-parameters.txt | 6 +++ > kernel/trace/trace.c | 51 +++++++++++++++++++ > 2 files changed, 57 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 6cfa6e3996cf..cec486217ccc 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6272,6 +6272,12 @@ > comma-separated list of trace events to enable. See > also Documentation/trace/events.rst > > + trace_instance=[instance-info] > + [FTRACE] Create an ring buffer instance early in boot up. > + This will be listed in: > + > + /sys/kernel/tracing/instances
Should this be "/sys/kernel/debug/tracing/instances"?
Ditto for the text for 'ftrace_boot_snapshot':
ftrace_boot_snapshot [FTRACE] On boot up, a snapshot will be taken of the ftrace ring buffer that can be read at: /sys/kernel/tracing/snapshot.
Everywhere else we use /sys/kernel/debug/tracing, though we do use /sys/kernel/tracing in Documentation/trace/ftrace.txt ?
I guess either works, but having just 1 or the other will help us not confuse users.
> + > trace_options=[option-list] > [FTRACE] Enable or disable tracer options at boot. > The option-list is a comma delimited list of options > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index a555a861b978..34ed504ffca9 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -48,6 +48,9 @@ > #include <linux/fsnotify.h> > #include <linux/irq_work.h> > #include <linux/workqueue.h> > +#include <linux/workqueue.h>
Duplicate include 1 line above.
> + > +#include <asm/setup.h> /* COMMAND_LINE_SIZE */ > > #include "trace.h" > #include "trace_output.h" > @@ -186,6 +189,9 @@ static char *default_bootup_tracer; > static bool allocate_snapshot; > static bool snapshot_at_boot; > > +static char boot_instance_info[COMMAND_LINE_SIZE] __initdata; > +static int boot_instance_index; > + > static int __init set_cmdline_ftrace(char *str) > { > strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); > @@ -239,6 +245,23 @@ static int __init boot_snapshot(char *str) > __setup("ftrace_boot_snapshot", boot_snapshot); > > > +static int __init boot_instance(char *str) > +{ > + char *slot = boot_instance_info + boot_instance_index; > + int left = COMMAND_LINE_SIZE - boot_instance_index;
A bit safer to use sizeof(boot_instance_info) instead of COMMAND_LINE_SIZE, so we can change the allocation size of boot_instance_info without having to keep them in sync.
These are mostly nits, you can add:
Reviewed-by: Ross Zwisler <zwisler@google.com>
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