[PATCH 10/91] tools api: Add a lightweight buffered reading api

Arnaldo Carvalho de Melo
2020-05-06T15:23:27Z

From: Ian Rogers <irogers@google.com>

The synthesize benchmark shows the majority of execution time going to
fgets and sscanf, necessary to parse /proc/pid/maps. Add a new buffered
reading library that will be used to replace these calls in a follow-up
CL. Add tests for the library to perf test.

Committer tests:

$ perf test api
63: Test api io : Ok
$

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrey Zhizhikin <andrey.z@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200415054050.31645-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/lib/api/io.h | 112 ++++++++++++
tools/perf/tests/Build | 1 +
tools/perf/tests/api-io.c | 304 ++++++++++++++++++++++++++++++++
tools/perf/tests/builtin-test.c | 4 +
tools/perf/tests/tests.h | 1 +
5 files changed, 422 insertions(+)
create mode 100644 tools/lib/api/io.h
create mode 100644 tools/perf/tests/api-io.c

diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h
new file mode 100644
index 000000000000..b7e55b5f8a4a
--- /dev/null
+++ b/tools/lib/api/io.h
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Lightweight buffered reading library.
+ *
+ * Copyright 2019 Google LLC.
+ */
+#ifndef __API_IO__
+#define __API_IO__
+
+struct io {
+ /* File descriptor being read/ */
+ int fd;
+ /* Size of the read buffer. */
+ unsigned int buf_len;
+ /* Pointer to storage for buffering read. */
+ char *buf;
+ /* End of the storage. */
+ char *end;
+ /* Currently accessed data pointer. */
+ char *data;
+ /* Set true on when the end of file on read error. */
+ bool eof;
+};
+
+static inline void io__init(struct io *io, int fd,
+ char *buf, unsigned int buf_len)
+{
+ io->fd = fd;
+ io->buf_len = buf_len;
+ io->buf = buf;
+ io->end = buf;
+ io->data = buf;
+ io->eof = false;
+}
+
+/* Reads one character from the "io" file with similar semantics to fgetc. */
+static inline int io__get_char(struct io *io)
+{
+ char *ptr = io->data;
+
+ if (io->eof)
+ return -1;
+
+ if (ptr == io->end) {
+ ssize_t n = read(io->fd, io->buf, io->buf_len);
+
+ if (n <= 0) {
+ io->eof = true;
+ return -1;
+ }
+ ptr = &io->buf[0];
+ io->end = &io->buf[n];
+ }
+ io->data = ptr + 1;
+ return *ptr;
+}
+
+/* Read a hexadecimal value with no 0x prefix into the out argument hex. If the
+ * first character isn't hexadecimal returns -2, io->eof returns -1, otherwise
+ * returns the character after the hexadecimal value which may be -1 for eof.
+ * If the read value is larger than a u64 the high-order bits will be dropped.
+ */
+static inline int io__get_hex(struct io *io, __u64 *hex)
+{
+ bool first_read = true;
+
+ *hex = 0;
+ while (true) {
+ int ch = io__get_char(io);
+
+ if (ch < 0)
+ return ch;
+ if (ch >= '0' && ch <= '9')
+ *hex = (*hex << 4) | (ch - '0');
+ else if (ch >= 'a' && ch <= 'f')
+ *hex = (*hex << 4) | (ch - 'a' + 10);
+ else if (ch >= 'A' && ch <= 'F')
+ *hex = (*hex << 4) | (ch - 'A' + 10);
+ else if (first_read)
+ return -2;
+ else
+ return ch;
+ first_read = false;
+ }
+}
+
+/* Read a positive decimal value with out argument dec. If the first character
+ * isn't a decimal returns -2, io->eof returns -1, otherwise returns the
+ * character after the decimal value which may be -1 for eof. If the read value
+ * is larger than a u64 the high-order bits will be dropped.
+ */
+static inline int io__get_dec(struct io *io, __u64 *dec)
+{
+ bool first_read = true;
+
+ *dec = 0;
+ while (true) {
+ int ch = io__get_char(io);
+
+ if (ch < 0)
+ return ch;
+ if (ch >= '0' && ch <= '9')
+ *dec = (*dec * 10) + ch - '0';
+ else if (first_read)
+ return -2;
+ else
+ return ch;
+ first_read = false;
+ }
+}
+
+#endif /* __API_IO__ */
diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index b3d1bf13ca07..c75557aeef0e 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -56,6 +56,7 @@ perf-y += mem2node.o
perf-y += maps.o
perf-y += time-utils-test.o
perf-y += genelf.o
+perf-y += api-io.o

$(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c tests/Build
$(call rule_mkdir)
diff --git a/tools/perf/tests/api-io.c b/tools/perf/tests/api-io.c
new file mode 100644
index 000000000000..2ada86ad6084
--- /dev/null
+++ b/tools/perf/tests/api-io.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "debug.h"
+#include "tests.h"
+#include <api/io.h>
+#include <linux/kernel.h>
+
+#define TEMPL "/tmp/perf-test-XXXXXX"
+
+#define EXPECT_EQUAL(val, expected) \
+do { \
+ if (val != expected) { \
+ pr_debug("%s:%d: %d != %d\n", \
+ __FILE__, __LINE__, val, expected); \
+ ret = -1; \
+ } \
+} while (0)
+
+#define EXPECT_EQUAL64(val, expected) \
+do { \
+ if (val != expected) { \
+ pr_debug("%s:%d: %lld != %lld\n", \
+ __FILE__, __LINE__, val, expected); \
+ ret = -1; \
+ } \
+} while (0)
+
+static int make_test_file(char path[PATH_MAX], const char *contents)
+{
+ ssize_t contents_len = strlen(contents);
+ int fd;
+
+ strcpy(path, TEMPL);
+ fd = mkstemp(path);
+ if (fd < 0) {
+ pr_debug("mkstemp failed");
+ return -1;
+ }
+ if (write(fd, contents, contents_len) < contents_len) {
+ pr_debug("short write");
+ close(fd);
+ unlink(path);
+ return -1;
+ }
+ close(fd);
+ return 0;
+}
+
+static int setup_test(char path[PATH_MAX], const char *contents,
+ size_t buf_size, struct io *io)
+{
+ if (make_test_file(path, contents))
+ return -1;
+
+ io->fd = open(path, O_RDONLY);
+ if (io->fd < 0) {
+ pr_debug("Failed to open '%s'\n", path);
+ unlink(path);
+ return -1;
+ }
+ io->buf = malloc(buf_size);
+ if (io->buf == NULL) {
+ pr_debug("Failed to allocate memory");
+ close(io->fd);
+ unlink(path);
+ return -1;
+ }
+ io__init(io, io->fd, io->buf, buf_size);
+ return 0;
+}
+
+static void cleanup_test(char path[PATH_MAX], struct io *io)
+{
+ free(io->buf);
+ close(io->fd);
+ unlink(path);
+}
+
+static int do_test_get_char(const char *test_string, size_t buf_size)
+{
+ char path[PATH_MAX];
+ struct io io;
+ int ch, ret = 0;
+ size_t i;
+
+ if (setup_test(path, test_string, buf_size, &io))
+ return -1;
+
+ for (i = 0; i < strlen(test_string); i++) {
+ ch = io__get_char(&io);
+
+ EXPECT_EQUAL(ch, test_string[i]);
+ EXPECT_EQUAL(io.eof, false);
+ }
+ ch = io__get_char(&io);
+ EXPECT_EQUAL(ch, -1);
+ EXPECT_EQUAL(io.eof, true);
+
+ cleanup_test(path, &io);
+ return ret;
+}
+
+static int test_get_char(void)
+{
+ int i, ret = 0;
+ size_t j;
+
+ static const char *const test_strings[] = {
+ "12345678abcdef90",
+ "a\nb\nc\nd\n",
+ "\a\b\t\v\f\r",
+ };
+ for (i = 0; i <= 10; i++) {
+ for (j = 0; j < ARRAY_SIZE(test_strings); j++) {
+ if (do_test_get_char(test_strings[j], 1 << i))
+ ret = -1;
+ }
+ }
+ return ret;
+}
+
+static int do_test_get_hex(const char *test_string,
+ __u64 val1, int ch1,
+ __u64 val2, int ch2,
+ __u64 val3, int ch3,
+ bool end_eof)
+{
+ char path[PATH_MAX];
+ struct io io;
+ int ch, ret = 0;
+ __u64 hex;
+
+ if (setup_test(path, test_string, 4, &io))
+ return -1;
+
+ ch = io__get_hex(&io, &hex);
+ EXPECT_EQUAL64(hex, val1);
+ EXPECT_EQUAL(ch, ch1);
+
+ ch = io__get_hex(&io, &hex);
+ EXPECT_EQUAL64(hex, val2);
+ EXPECT_EQUAL(ch, ch2);
+
+ ch = io__get_hex(&io, &hex);
+ EXPECT_EQUAL64(hex, val3);
+ EXPECT_EQUAL(ch, ch3);
+
+ EXPECT_EQUAL(io.eof, end_eof);
+
+ cleanup_test(path, &io);
+ return ret;
+}
+
+static int test_get_hex(void)
+{
+ int ret = 0;
+
+ if (do_test_get_hex("12345678abcdef90",
+ 0x12345678abcdef90, -1,
+ 0, -1,
+ 0, -1,
+ true))
+ ret = -1;
+
+ if (do_test_get_hex("1\n2\n3\n",
+ 1, '\n',
+ 2, '\n',
+ 3, '\n',
+ false))
+ ret = -1;
+
+ if (do_test_get_hex("12345678ABCDEF90;a;b",
+ 0x12345678abcdef90, ';',
+ 0xa, ';',
+ 0xb, -1,
+ true))
+ ret = -1;
+
+ if (do_test_get_hex("0x1x2x",
+ 0, 'x',
+ 1, 'x',
+ 2, 'x',
+ false))
+ ret = -1;
+
+ if (do_test_get_hex("x1x",
+ 0, -2,
+ 1, 'x',
+ 0, -1,
+ true))
+ ret = -1;
+
+ if (do_test_get_hex("10000000000000000000000000000abcdefgh99i",
+ 0xabcdef, 'g',
+ 0, -2,
+ 0x99, 'i',
+ false))
+ ret = -1;
+
+ return ret;
+}
+
+static int do_test_get_dec(const char *test_string,
+ __u64 val1, int ch1,
+ __u64 val2, int ch2,
+ __u64 val3, int ch3,
+ bool end_eof)
+{
+ char path[PATH_MAX];
+ struct io io;
+ int ch, ret = 0;
+ __u64 dec;
+
+ if (setup_test(path, test_string, 4, &io))
+ return -1;
+
+ ch = io__get_dec(&io, &dec);
+ EXPECT_EQUAL64(dec, val1);
+ EXPECT_EQUAL(ch, ch1);
+
+ ch = io__get_dec(&io, &dec);
+ EXPECT_EQUAL64(dec, val2);
+ EXPECT_EQUAL(ch, ch2);
+
+ ch = io__get_dec(&io, &dec);
+ EXPECT_EQUAL64(dec, val3);
+ EXPECT_EQUAL(ch, ch3);
+
+ EXPECT_EQUAL(io.eof, end_eof);
+
+ cleanup_test(path, &io);
+ return ret;
+}
+
+static int test_get_dec(void)
+{
+ int ret = 0;
+
+ if (do_test_get_dec("12345678abcdef90",
+ 12345678, 'a',
+ 0, -2,
+ 0, -2,
+ false))
+ ret = -1;
+
+ if (do_test_get_dec("1\n2\n3\n",
+ 1, '\n',
+ 2, '\n',
+ 3, '\n',
+ false))
+ ret = -1;
+
+ if (do_test_get_dec("12345678;1;2",
+ 12345678, ';',
+ 1, ';',
+ 2, -1,
+ true))
+ ret = -1;
+
+ if (do_test_get_dec("0x1x2x",
+ 0, 'x',
+ 1, 'x',
+ 2, 'x',
+ false))
+ ret = -1;
+
+ if (do_test_get_dec("x1x",
+ 0, -2,
+ 1, 'x',
+ 0, -1,
+ true))
+ ret = -1;
+
+ if (do_test_get_dec("10000000000000000000000000000000000000000000000000000000000123456789ab99c",
+ 123456789, 'a',
+ 0, -2,
+ 99, 'c',
+ false))
+ ret = -1;
+
+ return ret;
+}
+
+int test__api_io(struct test *test __maybe_unused,
+ int subtest __maybe_unused)
+{
+ int ret = 0;
+
+ if (test_get_char())
+ ret = TEST_FAIL;
+ if (test_get_hex())
+ ret = TEST_FAIL;
+ if (test_get_dec())
+ ret = TEST_FAIL;
+ return ret;
+}
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index b6322eb0f423..3471ec52ea11 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -309,6 +309,10 @@ static struct test generic_tests[] = {
.desc = "Test jit_write_elf",
.func = test__jit_write_elf,
},
+ {
+ .desc = "Test api io",
+ .func = test__api_io,
+ },
{
.desc = "maps__merge_in",
.func = test__maps__merge_in,
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index 61a1ab032080..d6d4ac34eeb7 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -112,6 +112,7 @@ int test__mem2node(struct test *t, int subtest);
int test__maps__merge_in(struct test *t, int subtest);
int test__time_utils(struct test *t, int subtest);
int test__jit_write_elf(struct test *test, int subtest);
+int test__api_io(struct test *test, int subtest);

bool test__bp_signal_is_supported(void);
bool test__bp_account_is_supported(void);
--
2.21.1