Commit 8f79870e authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

selftests/bpf: Extend uprobe/uretprobe triggering benchmarks 



Settle on three "flavors" of uprobe/uretprobe, installed on different
kinds of instruction: nop, push, and ret. All three are testing
different internal code paths emulating or single-stepping instructions,
so are interesting to compare and benchmark separately.

To ensure `push rbp` instruction we ensure that uprobe_target_push() is
not a leaf function by calling (global __weak) noop function and
returning something afterwards (if we don't do that, compiler will just
do a tail call optimization).

Also, we need to make sure that compiler isn't skipping frame pointer
generation, so let's add `-fno-omit-frame-pointers` to Makefile.

Just to give an idea of where we currently stand in terms of relative
performance of different uprobe/uretprobe cases vs a cheap syscall
(getpgid()) baseline, here are results from my local machine:

$ benchs/run_bench_uprobes.sh
base           :    1.561 ± 0.020M/s
uprobe-nop     :    0.947 ± 0.007M/s
uprobe-push    :    0.951 ± 0.004M/s
uprobe-ret     :    0.443 ± 0.007M/s
uretprobe-nop  :    0.471 ± 0.013M/s
uretprobe-push :    0.483 ± 0.004M/s
uretprobe-ret  :    0.306 ± 0.007M/s

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240301214551.1686095-1-andrii@kernel.org
parent 25703adf

tools/testing/selftests/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ LIBELF_CFLAGS := $(shell $(PKG_CONFIG) libelf --cflags 2>/dev/null) 
LIBELF_LIBS	:= $(shell $(PKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)



CFLAGS += -g $(OPT_FLAGS) -rdynamic					\

	  -Wall -Werror 						\

	  -Wall -Werror -fno-omit-frame-pointer				\

	  $(GENFLAGS) $(SAN_CFLAGS) $(LIBELF_CFLAGS)			\

	  -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR)		\

	  -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT)

tools/testing/selftests/bpf/bench.c

+12 −8
Original line number Diff line number Diff line
@@ -499,10 +499,12 @@ extern const struct bench bench_trig_fentry; 
extern const struct bench bench_trig_fentry_sleep;

extern const struct bench bench_trig_fmodret;

extern const struct bench bench_trig_uprobe_base;

extern const struct bench bench_trig_uprobe_with_nop;

extern const struct bench bench_trig_uretprobe_with_nop;

extern const struct bench bench_trig_uprobe_without_nop;

extern const struct bench bench_trig_uretprobe_without_nop;

extern const struct bench bench_trig_uprobe_nop;

extern const struct bench bench_trig_uretprobe_nop;

extern const struct bench bench_trig_uprobe_push;

extern const struct bench bench_trig_uretprobe_push;

extern const struct bench bench_trig_uprobe_ret;

extern const struct bench bench_trig_uretprobe_ret;

extern const struct bench bench_rb_libbpf;

extern const struct bench bench_rb_custom;

extern const struct bench bench_pb_libbpf;
@@ -541,10 +543,12 @@ static const struct bench *benchs[] = { 
	&bench_trig_fentry_sleep,

	&bench_trig_fmodret,

	&bench_trig_uprobe_base,

	&bench_trig_uprobe_with_nop,

	&bench_trig_uretprobe_with_nop,

	&bench_trig_uprobe_without_nop,

	&bench_trig_uretprobe_without_nop,

	&bench_trig_uprobe_nop,

	&bench_trig_uretprobe_nop,

	&bench_trig_uprobe_push,

	&bench_trig_uretprobe_push,

	&bench_trig_uprobe_ret,

	&bench_trig_uretprobe_ret,

	&bench_rb_libbpf,

	&bench_rb_custom,

	&bench_pb_libbpf,

tools/testing/selftests/bpf/benchs/bench_trigger.c

+81 −37
Original line number Diff line number Diff line
@@ -113,12 +113,25 @@ static void trigger_fmodret_setup(void) 
 * GCC doesn't generate stack setup preample for these functions due to them

 * having no input arguments and doing nothing in the body.

 */

__weak void uprobe_target_with_nop(void)

__weak void uprobe_target_nop(void)

{

	asm volatile ("nop");

}



__weak void uprobe_target_without_nop(void)

__weak void opaque_noop_func(void)

{

}



__weak int uprobe_target_push(void)

{

	/* overhead of function call is negligible compared to uprobe

	 * triggering, so this shouldn't affect benchmark results much

	 */

	opaque_noop_func();

	return 1;

}



__weak void uprobe_target_ret(void)

{

	asm volatile ("");

}
@@ -126,27 +139,34 @@ __weak void uprobe_target_without_nop(void) 
static void *uprobe_base_producer(void *input)

{

	while (true) {

		uprobe_target_with_nop();

		uprobe_target_nop();

		atomic_inc(&base_hits.value);

	}

	return NULL;

}



static void *uprobe_producer_with_nop(void *input)

static void *uprobe_producer_nop(void *input)

{

	while (true)

		uprobe_target_with_nop();

		uprobe_target_nop();

	return NULL;

}



static void *uprobe_producer_without_nop(void *input)

static void *uprobe_producer_push(void *input)

{

	while (true)

		uprobe_target_without_nop();

		uprobe_target_push();

	return NULL;

}



static void usetup(bool use_retprobe, bool use_nop)

static void *uprobe_producer_ret(void *input)

{

	while (true)

		uprobe_target_ret();

	return NULL;

}



static void usetup(bool use_retprobe, void *target_addr)

{

	size_t uprobe_offset;

	struct bpf_link *link;
@@ -159,11 +179,7 @@ static void usetup(bool use_retprobe, bool use_nop) 
		exit(1);

	}



	if (use_nop)

		uprobe_offset = get_uprobe_offset(&uprobe_target_with_nop);

	else

		uprobe_offset = get_uprobe_offset(&uprobe_target_without_nop);



	uprobe_offset = get_uprobe_offset(target_addr);

	link = bpf_program__attach_uprobe(ctx.skel->progs.bench_trigger_uprobe,

					  use_retprobe,

					  -1 /* all PIDs */,
@@ -176,24 +192,34 @@ static void usetup(bool use_retprobe, bool use_nop) 
	ctx.skel->links.bench_trigger_uprobe = link;

}



static void uprobe_setup_with_nop(void)

static void uprobe_setup_nop(void)

{

	usetup(false, true);

	usetup(false, &uprobe_target_nop);

}



static void uretprobe_setup_with_nop(void)

static void uretprobe_setup_nop(void)

{

	usetup(true, true);

	usetup(true, &uprobe_target_nop);

}



static void uprobe_setup_without_nop(void)

static void uprobe_setup_push(void)

{

	usetup(false, false);

	usetup(false, &uprobe_target_push);

}



static void uretprobe_setup_without_nop(void)

static void uretprobe_setup_push(void)

{

	usetup(true, false);

	usetup(true, &uprobe_target_push);

}



static void uprobe_setup_ret(void)

{

	usetup(false, &uprobe_target_ret);

}



static void uretprobe_setup_ret(void)

{

	usetup(true, &uprobe_target_ret);

}



const struct bench bench_trig_base = {
@@ -274,37 +300,55 @@ const struct bench bench_trig_uprobe_base = { 
	.report_final = hits_drops_report_final,

};



const struct bench bench_trig_uprobe_with_nop = {

	.name = "trig-uprobe-with-nop",

	.setup = uprobe_setup_with_nop,

	.producer_thread = uprobe_producer_with_nop,

const struct bench bench_trig_uprobe_nop = {

	.name = "trig-uprobe-nop",

	.setup = uprobe_setup_nop,

	.producer_thread = uprobe_producer_nop,

	.measure = trigger_measure,

	.report_progress = hits_drops_report_progress,

	.report_final = hits_drops_report_final,

};



const struct bench bench_trig_uretprobe_nop = {

	.name = "trig-uretprobe-nop",

	.setup = uretprobe_setup_nop,

	.producer_thread = uprobe_producer_nop,

	.measure = trigger_measure,

	.report_progress = hits_drops_report_progress,

	.report_final = hits_drops_report_final,

};



const struct bench bench_trig_uprobe_push = {

	.name = "trig-uprobe-push",

	.setup = uprobe_setup_push,

	.producer_thread = uprobe_producer_push,

	.measure = trigger_measure,

	.report_progress = hits_drops_report_progress,

	.report_final = hits_drops_report_final,

};



const struct bench bench_trig_uretprobe_with_nop = {

	.name = "trig-uretprobe-with-nop",

	.setup = uretprobe_setup_with_nop,

	.producer_thread = uprobe_producer_with_nop,

const struct bench bench_trig_uretprobe_push = {

	.name = "trig-uretprobe-push",

	.setup = uretprobe_setup_push,

	.producer_thread = uprobe_producer_push,

	.measure = trigger_measure,

	.report_progress = hits_drops_report_progress,

	.report_final = hits_drops_report_final,

};



const struct bench bench_trig_uprobe_without_nop = {

	.name = "trig-uprobe-without-nop",

	.setup = uprobe_setup_without_nop,

	.producer_thread = uprobe_producer_without_nop,

const struct bench bench_trig_uprobe_ret = {

	.name = "trig-uprobe-ret",

	.setup = uprobe_setup_ret,

	.producer_thread = uprobe_producer_ret,

	.measure = trigger_measure,

	.report_progress = hits_drops_report_progress,

	.report_final = hits_drops_report_final,

};



const struct bench bench_trig_uretprobe_without_nop = {

	.name = "trig-uretprobe-without-nop",

	.setup = uretprobe_setup_without_nop,

	.producer_thread = uprobe_producer_without_nop,

const struct bench bench_trig_uretprobe_ret = {

	.name = "trig-uretprobe-ret",

	.setup = uretprobe_setup_ret,

	.producer_thread = uprobe_producer_ret,

	.measure = trigger_measure,

	.report_progress = hits_drops_report_progress,

	.report_final = hits_drops_report_final,

tools/testing/selftests/bpf/benchs/run_bench_uprobes.sh

0 → 100755
+9 −0
Original line number Diff line number Diff line 
#!/bin/bash



set -eufo pipefail



for i in base {uprobe,uretprobe}-{nop,push,ret}

do

	summary=$(sudo ./bench -w2 -d5 -a trig-$i | tail -n1 | cut -d'(' -f1 | cut -d' ' -f3-)

	printf "%-15s: %s\n" $i "$summary"

done