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Date: Thu, 9 Apr 2020 20:40:47 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Petr Mladek <pmladek@...e.com>,
Andrey Zhizhikin <andrey.z@...il.com>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Thomas Gleixner <tglx@...utronix.de>,
Kan Liang <kan.liang@...ux.intel.com>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Cc: Stephane Eranian <eranian@...gle.com>,
Ian Rogers <irogers@...gle.com>
Subject: [PATCH v3 1/2] tools api: add a lightweight buffered reading api
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.
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/lib/api/io.h | 112 ++++++++++++++++++++++++++++++++
tools/perf/tests/Build | 1 +
tools/perf/tests/builtin-test.c | 4 ++
tools/perf/tests/tests.h | 1 +
4 files changed, 118 insertions(+)
create mode 100644 tools/lib/api/io.h
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/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);
--
2.26.0.110.g2183baf09c-goog
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