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Date: Sat, 11 Sep 2021 21:50:42 +0800
From: Yinan Liu <yinan@...ux.alibaba.com>
To: yinan@...ux.alibaba.com, rostedt@...dmis.org,
mark-pk.tsai@...iatek.com, peterz@...radead.org, mingo@...hat.com,
linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] scripts: ftrace - move the sort-processing in ftrace_init to compile time
When ftrace is enabled, ftrace_init will consume a period of
time, usually around 15~20 ms. Approximately 40% of the time is
consumed by sort-processing. Moving the sort-processing to the
compile time can speed up the kernel boot process.
performance test:
env: Intel(R) Xeon(R) CPU E5-2682 v4 @ 2.50GHz
method: before and after patching, compare the
total time of ftrace_init(), and verify
the functionality of ftrace.
avg_time of ftrace_init:
with patch: 8.352 ms
without patch: 15.763 ms
Signed-off-by: Yinan Liu <yinan@...ux.alibaba.com>
---
kernel/trace/ftrace.c | 5 ++-
scripts/link-vmlinux.sh | 6 +--
scripts/sorttable.c | 2 +
scripts/sorttable.h | 109 +++++++++++++++++++++++++++++++++++++++++++++++-
4 files changed, 115 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7efbc8aaf7f6..c236da868990 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6189,8 +6189,9 @@ static int ftrace_process_locs(struct module *mod,
if (!count)
return 0;
- sort(start, count, sizeof(*start),
- ftrace_cmp_ips, NULL);
+ if (mod)
+ sort(start, count, sizeof(*start),
+ ftrace_cmp_ips, NULL);
start_pg = ftrace_allocate_pages(count);
if (!start_pg)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index d74cee5c4326..57f53b0f4a8a 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -409,6 +409,9 @@ if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
${RESOLVE_BTFIDS} vmlinux
fi
+info SYSMAP System.map
+mksysmap vmlinux System.map
+
if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
info SORTTAB vmlinux
if ! sorttable vmlinux; then
@@ -417,9 +420,6 @@ if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
fi
fi
-info SYSMAP System.map
-mksysmap vmlinux System.map
-
# step a (see comment above)
if [ -n "${CONFIG_KALLSYMS}" ]; then
mksysmap ${kallsyms_vmlinux} .tmp_System.map
diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 0ef3abfc4a51..11a595ca256b 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -30,6 +30,8 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
+#include <errno.h>
+#include <pthread.h>
#include <tools/be_byteshift.h>
#include <tools/le_byteshift.h>
diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index a2baa2fefb13..db6c38c61986 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -19,6 +19,9 @@
#undef extable_ent_size
#undef compare_extable
+#undef get_mcount_loc
+#undef sort_mcount_loc
+#undef mcount_loc
#undef do_sort
#undef Elf_Addr
#undef Elf_Ehdr
@@ -41,6 +44,9 @@
#ifdef SORTTABLE_64
# define extable_ent_size 16
# define compare_extable compare_extable_64
+# define get_mcount_loc get_mcount_loc_64
+# define sort_mcount_loc sort_mcount_loc_64
+# define mcount_loc mcount_loc_64
# define do_sort do_sort_64
# define Elf_Addr Elf64_Addr
# define Elf_Ehdr Elf64_Ehdr
@@ -62,6 +68,9 @@
#else
# define extable_ent_size 8
# define compare_extable compare_extable_32
+# define get_mcount_loc get_mcount_loc_32
+# define sort_mcount_loc sort_mcount_loc_32
+# define mcount_loc mcount_loc_32
# define do_sort do_sort_32
# define Elf_Addr Elf32_Addr
# define Elf_Ehdr Elf32_Ehdr
@@ -84,8 +93,6 @@
#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
/* ORC unwinder only support X86_64 */
-#include <errno.h>
-#include <pthread.h>
#include <asm/orc_types.h>
#define ERRSTR_MAXSZ 256
@@ -191,6 +198,62 @@ static int compare_extable(const void *a, const void *b)
return 1;
return 0;
}
+struct mcount_loc {
+ Elf_Ehdr *ehdr;
+ Elf_Shdr *init_data_sec;
+ uint_t start_mcount_loc;
+ uint_t stop_mcount_loc;
+};
+
+/* Sort the addresses stored between __start_mcount to __stop_mcount */
+static void *sort_mcount_loc(void *arg)
+{
+ struct mcount_loc *mstruct = (struct mcount_loc *)arg;
+ uint_t offset = mstruct->start_mcount_loc - _r(&(mstruct->init_data_sec)->sh_addr)
+ + _r(&(mstruct->init_data_sec)->sh_offset);
+ uint_t count = mstruct->stop_mcount_loc - mstruct->start_mcount_loc;
+ unsigned char *start = (void *)mstruct->ehdr + offset;
+
+ qsort(start, count/sizeof(uint_t), sizeof(uint_t), compare_extable);
+ return NULL;
+}
+
+/* get the address of __start_mcount_loc and __stop_mcount_loc*/
+static void get_mcount_loc(uint_t *_start, uint_t *_stop)
+{
+ FILE *file_start, *file_stop;
+ char start_buff[20];
+ char end_buff[20];
+ int len = 0;
+
+ file_start = popen(" grep start_mcount System.map | awk '{print $1}' ", "r");
+ if (!file_start) {
+ fprintf(stderr, "get start_mcount_loc error!");
+ return;
+ }
+
+ file_stop = popen(" grep stop_mcount System.map | awk '{print $1}' ", "r");
+ if (!file_stop) {
+ fprintf(stderr, "get stop_mcount_loc error!");
+ pclose(file_start);
+ return;
+ }
+
+ while (fgets(start_buff, sizeof(start_buff), file_start) != NULL) {
+ len = strlen(start_buff);
+ start_buff[len - 1] = '\0';
+ }
+ *_start = strtoul(start_buff, NULL, 16);
+
+ while (fgets(end_buff, sizeof(end_buff), file_stop) != NULL) {
+ len = strlen(end_buff);
+ end_buff[len - 1] = '\0';
+ }
+ *_stop = strtoul(end_buff, NULL, 16);
+
+ pclose(file_start);
+ pclose(file_stop);
+}
static int do_sort(Elf_Ehdr *ehdr,
char const *const fname,
@@ -217,6 +280,10 @@ static int do_sort(Elf_Ehdr *ehdr,
int idx;
unsigned int shnum;
unsigned int shstrndx;
+ struct mcount_loc mstruct;
+ uint_t _start_mcount_loc = 0;
+ uint_t _stop_mcount_loc = 0;
+ pthread_t mcount_sort_thread;
#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
unsigned int orc_ip_size = 0;
unsigned int orc_size = 0;
@@ -253,6 +320,14 @@ static int do_sort(Elf_Ehdr *ehdr,
symtab_shndx = (Elf32_Word *)((const char *)ehdr +
_r(&s->sh_offset));
+ /* locate the mcount_loc */
+ if (!strcmp(secstrings + idx, ".init.data")) {
+ get_mcount_loc(&_start_mcount_loc, &_stop_mcount_loc);
+ mstruct.ehdr = ehdr;
+ mstruct.init_data_sec = s;
+ mstruct.start_mcount_loc = _start_mcount_loc;
+ mstruct.stop_mcount_loc = _stop_mcount_loc;
+ }
#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
/* locate the ORC unwind tables */
if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
@@ -294,6 +369,21 @@ static int do_sort(Elf_Ehdr *ehdr,
goto out;
}
#endif
+ if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) {
+ fprintf(stderr,
+ "incomplete mcount_loc in file: %s\n",
+ fname);
+ goto out;
+ }
+
+ /* create thread to sort mcount_loc concurrently */
+ if (pthread_create(&mcount_sort_thread, NULL, &sort_mcount_loc, &mstruct)) {
+ fprintf(stderr,
+ "pthread_create mcount_sort_thread failed '%s': %s\n",
+ strerror(errno), fname);
+ goto out;
+ }
+
if (!extab_sec) {
fprintf(stderr, "no __ex_table in file: %s\n", fname);
goto out;
@@ -376,5 +466,20 @@ static int do_sort(Elf_Ehdr *ehdr,
}
}
#endif
+ if (mcount_sort_thread) {
+ void *retval = NULL;
+ /* wait for mcount sort done */
+ rc = pthread_join(mcount_sort_thread, &retval);
+ if (rc)
+ fprintf(stderr,
+ "pthread_join failed '%s': %s\n",
+ strerror(errno), fname);
+ else if (retval) {
+ rc = -1;
+ fprintf(stderr,
+ "failed to sort mcount '%s': %s\n",
+ (char *)retval, fname);
+ }
+ }
return rc;
}
--
2.14.4.44.g2045bb6
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