Florian Mayer | 75905df | 2018-05-08 17:44:08 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | // Print timestamps when pages were read to stdout. |
| 18 | // This data is useful to compute rate of events from the kernel. |
| 19 | |
| 20 | #include <thread> |
| 21 | |
| 22 | #include <fcntl.h> // splice |
| 23 | #include <inttypes.h> |
| 24 | #include <stdint.h> |
| 25 | #include <unistd.h> // pipe |
| 26 | |
| 27 | #include "perfetto/base/logging.h" |
| 28 | #include "perfetto/base/scoped_file.h" |
| 29 | #include "perfetto/base/time.h" |
| 30 | #include "perfetto/base/utils.h" |
| 31 | |
| 32 | namespace perfetto { |
| 33 | namespace { |
| 34 | |
| 35 | void SetBlocking(int fd, bool is_blocking) { |
| 36 | int flags = fcntl(fd, F_GETFL, 0); |
| 37 | flags = (is_blocking) ? (flags & ~O_NONBLOCK) : (flags | O_NONBLOCK); |
| 38 | PERFETTO_CHECK(fcntl(fd, F_SETFL, flags) == 0); |
| 39 | } |
| 40 | |
| 41 | __attribute__((__noreturn__)) void ReadLoop(int fd) { |
| 42 | char buf[4096]; |
| 43 | while (true) { |
| 44 | base::ignore_result(read(fd, &buf, sizeof(buf))); |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | int PipestatsMain(int argc, char** argv) { |
| 49 | PERFETTO_CHECK(argc == 2); |
| 50 | base::ScopedFile trace_fd(open(argv[1], O_RDONLY)); |
| 51 | PERFETTO_CHECK(trace_fd); |
| 52 | std::thread reader(ReadLoop, trace_fd.get()); |
| 53 | |
| 54 | int pipe_fds[2]; |
| 55 | PERFETTO_CHECK(pipe(&pipe_fds[0]) == 0); |
| 56 | base::ScopedFile staging_read_fd(pipe_fds[0]); |
| 57 | base::ScopedFile staging_write_fd(pipe_fds[1]); |
| 58 | |
| 59 | // Make reads from the raw pipe blocking so that splice() can sleep. |
| 60 | SetBlocking(*trace_fd, true); |
| 61 | |
| 62 | // Reads from the staging pipe are always non-blocking. |
| 63 | SetBlocking(*staging_read_fd, false); |
| 64 | |
| 65 | // Note: O_NONBLOCK seems to be ignored by splice() on the target pipe. The |
| 66 | // blocking vs non-blocking behavior is controlled solely by the |
| 67 | // SPLICE_F_NONBLOCK flag passed to splice(). |
| 68 | SetBlocking(*staging_write_fd, false); |
| 69 | |
| 70 | while (true) { |
| 71 | ssize_t splice_res = splice(*trace_fd, nullptr, *staging_write_fd, nullptr, |
| 72 | base::kPageSize, SPLICE_F_MOVE); |
| 73 | if (splice_res > 0) { |
| 74 | auto cur = base::GetWallTimeNs(); |
| 75 | printf("%" PRId64 "\n", int64_t(cur.count())); |
| 76 | } |
| 77 | } |
| 78 | } |
| 79 | |
| 80 | } // namespace |
| 81 | } // namespace perfetto |
| 82 | |
| 83 | int main(int argc, char** argv) { |
| 84 | return perfetto::PipestatsMain(argc, argv); |
| 85 | } |