blob: 15fbe27ceb985d788c0f3aeb2619f6244e8a90a6 [file] [log] [blame]
/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Print timestamps when pages were read to stdout.
// This data is useful to compute rate of events from the kernel.
#include <thread>
#include <fcntl.h> // splice
#include <inttypes.h>
#include <stdint.h>
#include <unistd.h> // pipe
#include "perfetto/base/logging.h"
#include "perfetto/base/scoped_file.h"
#include "perfetto/base/time.h"
#include "perfetto/base/utils.h"
namespace perfetto {
namespace {
void SetBlocking(int fd, bool is_blocking) {
int flags = fcntl(fd, F_GETFL, 0);
flags = (is_blocking) ? (flags & ~O_NONBLOCK) : (flags | O_NONBLOCK);
PERFETTO_CHECK(fcntl(fd, F_SETFL, flags) == 0);
}
__attribute__((__noreturn__)) void ReadLoop(int fd) {
char buf[4096];
while (true) {
base::ignore_result(read(fd, &buf, sizeof(buf)));
}
}
int PipestatsMain(int argc, char** argv) {
PERFETTO_CHECK(argc == 2);
base::ScopedFile trace_fd(base::OpenFile(argv[1], O_RDONLY));
PERFETTO_CHECK(trace_fd);
std::thread reader(ReadLoop, trace_fd.get());
int pipe_fds[2];
PERFETTO_CHECK(pipe(&pipe_fds[0]) == 0);
base::ScopedFile staging_read_fd(pipe_fds[0]);
base::ScopedFile staging_write_fd(pipe_fds[1]);
// Make reads from the raw pipe blocking so that splice() can sleep.
SetBlocking(*trace_fd, true);
// Reads from the staging pipe are always non-blocking.
SetBlocking(*staging_read_fd, false);
// Note: O_NONBLOCK seems to be ignored by splice() on the target pipe. The
// blocking vs non-blocking behavior is controlled solely by the
// SPLICE_F_NONBLOCK flag passed to splice().
SetBlocking(*staging_write_fd, false);
while (true) {
ssize_t splice_res = splice(*trace_fd, nullptr, *staging_write_fd, nullptr,
base::kPageSize, SPLICE_F_MOVE);
if (splice_res > 0) {
auto cur = base::GetWallTimeNs();
printf("%" PRId64 "\n", int64_t(cur.count()));
}
}
}
} // namespace
} // namespace perfetto
int main(int argc, char** argv) {
return perfetto::PipestatsMain(argc, argv);
}