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Message-ID: <20250405031213.3502708-1-howardchu95@gmail.com>
Date: Fri, 4 Apr 2025 20:12:13 -0700
From: Howard Chu <howardchu95@...il.com>
To: peterz@...radead.org
Cc: mingo@...hat.com,
acme@...nel.org,
namhyung@...nel.org,
mark.rutland@....com,
alexander.shishkin@...ux.intel.com,
jolsa@...nel.org,
irogers@...gle.com,
adrian.hunter@...el.com,
kan.liang@...ux.intel.com,
james.clark@...aro.org,
howardchu95@...il.com,
charlie@...osinc.com,
mpetlan@...hat.com,
vmolnaro@...hat.com,
linux@...blig.org,
mhiramat@...nel.org,
leo.yan@....com,
dima@...retsauce.net,
linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
krzysztof.m.lopatowski@...il.com
Subject: [PATCH v1] perf trace: Speed up startup time by bypassing the creation of kernel maps
If perf trace isn't run with '--call-graph' and '--kernel-syscall-graph'
options, e.g.
sudo ./perf trace --call-graph fp --kernel-syscall-graph -a
there is no need for creating kernel maps.
before:
perf $ time sudo ./perf trace -- sleep 1
? ( ): sleep/3462908 ... [continued]: execve()) = 0
...
1001.459 ( ): sleep/3463166 exit_group() = ?
real 0m2.834s
user 0m0.011s
sys 0m0.012s
after:
perf $ time sudo ./perf trace -- sleep 1
? ( ): sleep/3459948 ... [continued]: execve()) = 0
...
1001.471 ( ): 3459948 exit_group() = ?
real 0m1.810s
user 0m0.008s
sys 0m0.015s
I also want to express my gratitude to Krzysztof Łopatowski—his
profiling of the perf trace [1] inspired this patch. I'm not sure why
the discussion stalled, and I apologize for not being able to answer his
questions. Since his findings significantly improve the startup time of
perf trace, I don't want to take credit for that. So Krzysztof, please
let me know if you'd like a Suggested-by: or anything else.
[1]: https://lore.kernel.org/linux-perf-users/CAOQCU67EsHyw_FsqGbRuityahZTSAtWzffU=hLUJ7K=aZ=1hhA@mail.gmail.com/
Signed-off-by: Howard Chu <howardchu95@...il.com>
Cc: "Krzysztof Łopatowski" <krzysztof.m.lopatowski@...il.com>
---
tools/perf/builtin-buildid-list.c | 2 +-
tools/perf/builtin-trace.c | 2 +-
tools/perf/tests/code-reading.c | 2 +-
tools/perf/tests/dlfilter-test.c | 2 +-
tools/perf/tests/dwarf-unwind.c | 2 +-
tools/perf/tests/mmap-thread-lookup.c | 2 +-
tools/perf/tests/symbols.c | 2 +-
tools/perf/util/machine.c | 6 +++---
tools/perf/util/machine.h | 2 +-
tools/perf/util/probe-event.c | 2 +-
10 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/tools/perf/builtin-buildid-list.c b/tools/perf/builtin-buildid-list.c
index 52dfacaff8e3..357201d8ef0c 100644
--- a/tools/perf/builtin-buildid-list.c
+++ b/tools/perf/builtin-buildid-list.c
@@ -47,7 +47,7 @@ static void buildid__show_kernel_maps(void)
{
struct machine *machine;
- machine = machine__new_host();
+ machine = machine__new_host(true);
machine__for_each_kernel_map(machine, buildid__map_cb, NULL);
machine__delete(machine);
}
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index f55a8a6481f2..39f23ce39842 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1963,7 +1963,7 @@ static int trace__symbols_init(struct trace *trace, struct evlist *evlist)
if (err)
return err;
- trace->host = machine__new_host();
+ trace->host = machine__new_host(callchain_param.enabled && trace->kernel_syscallchains);
if (trace->host == NULL)
return -ENOMEM;
diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index cf6edbe697b2..17c7b9f95532 100644
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -654,7 +654,7 @@ static int do_test_code_reading(bool try_kcore)
pid = getpid();
- machine = machine__new_host();
+ machine = machine__new_host(true);
machine->env = &perf_env;
ret = machine__create_kernel_maps(machine);
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index 54f59d1246bc..11f70ebabacf 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -352,7 +352,7 @@ static int test__dlfilter_test(struct test_data *td)
return test_result("Failed to find program symbols", TEST_FAIL);
pr_debug("Creating new host machine structure\n");
- td->machine = machine__new_host();
+ td->machine = machine__new_host(true);
td->machine->env = &perf_env;
td->fd = creat(td->perf_data_file_name, 0644);
diff --git a/tools/perf/tests/dwarf-unwind.c b/tools/perf/tests/dwarf-unwind.c
index 4803ab2d97ba..b76712f68403 100644
--- a/tools/perf/tests/dwarf-unwind.c
+++ b/tools/perf/tests/dwarf-unwind.c
@@ -203,7 +203,7 @@ noinline int test__dwarf_unwind(struct test_suite *test __maybe_unused,
struct thread *thread;
int err = -1;
- machine = machine__new_host();
+ machine = machine__new_host(true);
if (!machine) {
pr_err("Could not get machine\n");
return -1;
diff --git a/tools/perf/tests/mmap-thread-lookup.c b/tools/perf/tests/mmap-thread-lookup.c
index ddd1da9a4ba9..194b5affaa41 100644
--- a/tools/perf/tests/mmap-thread-lookup.c
+++ b/tools/perf/tests/mmap-thread-lookup.c
@@ -167,7 +167,7 @@ static int mmap_events(synth_cb synth)
*/
TEST_ASSERT_VAL("failed to create threads", !threads_create());
- machine = machine__new_host();
+ machine = machine__new_host(true);
dump_trace = verbose > 1 ? 1 : 0;
diff --git a/tools/perf/tests/symbols.c b/tools/perf/tests/symbols.c
index ee20a366f32f..6b22a451211a 100644
--- a/tools/perf/tests/symbols.c
+++ b/tools/perf/tests/symbols.c
@@ -19,7 +19,7 @@ struct test_info {
static int init_test_info(struct test_info *ti)
{
- ti->machine = machine__new_host();
+ ti->machine = machine__new_host(true);
if (!ti->machine) {
pr_debug("machine__new_host() failed!\n");
return TEST_FAIL;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 55d4977b9913..b1828e3922f2 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -125,14 +125,14 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
return 0;
}
-struct machine *machine__new_host(void)
+struct machine *machine__new_host(bool create_kmaps)
{
struct machine *machine = malloc(sizeof(*machine));
if (machine != NULL) {
machine__init(machine, "", HOST_KERNEL_ID);
- if (machine__create_kernel_maps(machine) < 0)
+ if (create_kmaps && machine__create_kernel_maps(machine) < 0)
goto out_delete;
machine->env = &perf_env;
@@ -146,7 +146,7 @@ struct machine *machine__new_host(void)
struct machine *machine__new_kallsyms(void)
{
- struct machine *machine = machine__new_host();
+ struct machine *machine = machine__new_host(true);
/*
* FIXME:
* 1) We should switch to machine__load_kallsyms(), i.e. not explicitly
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index ae3e5542d57d..e6faf8cd06e7 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -163,7 +163,7 @@ struct thread *machine__findnew_guest_code(struct machine *machine, pid_t pid);
void machines__set_id_hdr_size(struct machines *machines, u16 id_hdr_size);
void machines__set_comm_exec(struct machines *machines, bool comm_exec);
-struct machine *machine__new_host(void);
+struct machine *machine__new_host(bool create_kmaps);
struct machine *machine__new_kallsyms(void);
int machine__init(struct machine *machine, const char *root_dir, pid_t pid);
void machine__exit(struct machine *machine);
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 307ad6242a4e..6b5b5542f454 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -94,7 +94,7 @@ int init_probe_symbol_maps(bool user_only)
if (symbol_conf.vmlinux_name)
pr_debug("Use vmlinux: %s\n", symbol_conf.vmlinux_name);
- host_machine = machine__new_host();
+ host_machine = machine__new_host(true);
if (!host_machine) {
pr_debug("machine__new_host() failed.\n");
symbol__exit();
--
2.45.2
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