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H A Dftrace-ops.cb56c68f705cad0cff61fbe132c66ced2c737c65c Tue Jan 03 13:49:12 CET 2023 Mark Rutland <mark.rutland@arm.com> ftrace: Add sample with custom ops

When reworking core ftrace code or architectural ftrace code, it's often
necessary to test/analyse/benchmark a number of ftrace_ops
configurations. This patch adds a module which can be used to explore
some of those configurations.

I'm using this to benchmark various options for changing the way
trampolines and handling of ftrace_ops work on arm64, and ensuring other
architectures aren't adversely affected.

For example, in a QEMU+KVM VM running on a 2GHz Xeon E5-2660
workstation, loading the module in various configurations produces:

| # insmod ftrace-ops.ko
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1681558ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_irrelevant=5
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 5
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1693042ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_relevant=2
| ftrace_ops: registering:
| relevant ops: 2
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 11965582ns (119ns / call)

| # insmod ftrace-ops.ko save_regs=true
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: YES
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 4459624ns (44ns / call)

Link: https://lkml.kernel.org/r/20230103124912.2948963-4-mark.rutland@arm.com

Cc: Florent Revest <revest@chromium.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
H A DMakefilediff b56c68f705cad0cff61fbe132c66ced2c737c65c Tue Jan 03 13:49:12 CET 2023 Mark Rutland <mark.rutland@arm.com> ftrace: Add sample with custom ops

When reworking core ftrace code or architectural ftrace code, it's often
necessary to test/analyse/benchmark a number of ftrace_ops
configurations. This patch adds a module which can be used to explore
some of those configurations.

I'm using this to benchmark various options for changing the way
trampolines and handling of ftrace_ops work on arm64, and ensuring other
architectures aren't adversely affected.

For example, in a QEMU+KVM VM running on a 2GHz Xeon E5-2660
workstation, loading the module in various configurations produces:

| # insmod ftrace-ops.ko
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1681558ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_irrelevant=5
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 5
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1693042ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_relevant=2
| ftrace_ops: registering:
| relevant ops: 2
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 11965582ns (119ns / call)

| # insmod ftrace-ops.ko save_regs=true
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: YES
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 4459624ns (44ns / call)

Link: https://lkml.kernel.org/r/20230103124912.2948963-4-mark.rutland@arm.com

Cc: Florent Revest <revest@chromium.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
/linux/samples/
H A DMakefilediff b56c68f705cad0cff61fbe132c66ced2c737c65c Tue Jan 03 13:49:12 CET 2023 Mark Rutland <mark.rutland@arm.com> ftrace: Add sample with custom ops

When reworking core ftrace code or architectural ftrace code, it's often
necessary to test/analyse/benchmark a number of ftrace_ops
configurations. This patch adds a module which can be used to explore
some of those configurations.

I'm using this to benchmark various options for changing the way
trampolines and handling of ftrace_ops work on arm64, and ensuring other
architectures aren't adversely affected.

For example, in a QEMU+KVM VM running on a 2GHz Xeon E5-2660
workstation, loading the module in various configurations produces:

| # insmod ftrace-ops.ko
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1681558ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_irrelevant=5
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 5
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1693042ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_relevant=2
| ftrace_ops: registering:
| relevant ops: 2
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 11965582ns (119ns / call)

| # insmod ftrace-ops.ko save_regs=true
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: YES
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 4459624ns (44ns / call)

Link: https://lkml.kernel.org/r/20230103124912.2948963-4-mark.rutland@arm.com

Cc: Florent Revest <revest@chromium.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
H A DKconfigdiff b56c68f705cad0cff61fbe132c66ced2c737c65c Tue Jan 03 13:49:12 CET 2023 Mark Rutland <mark.rutland@arm.com> ftrace: Add sample with custom ops

When reworking core ftrace code or architectural ftrace code, it's often
necessary to test/analyse/benchmark a number of ftrace_ops
configurations. This patch adds a module which can be used to explore
some of those configurations.

I'm using this to benchmark various options for changing the way
trampolines and handling of ftrace_ops work on arm64, and ensuring other
architectures aren't adversely affected.

For example, in a QEMU+KVM VM running on a 2GHz Xeon E5-2660
workstation, loading the module in various configurations produces:

| # insmod ftrace-ops.ko
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1681558ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_irrelevant=5
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 5
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1693042ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_relevant=2
| ftrace_ops: registering:
| relevant ops: 2
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 11965582ns (119ns / call)

| # insmod ftrace-ops.ko save_regs=true
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: YES
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 4459624ns (44ns / call)

Link: https://lkml.kernel.org/r/20230103124912.2948963-4-mark.rutland@arm.com

Cc: Florent Revest <revest@chromium.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>