如何在默认情况下禁用v8.cpu_profiler事件中计算样本的开始时间？

Question

Chrome DevTools将8509.5显示为调用堆栈的开始时间。我在性能配置文件中标识了该调用堆栈，但是我不明白该数字是如何计算的。

{
    "pid": 16232,
    "tid": 8608,
    "ts": 268814551135,
    "ph": "P",
    "cat": "disabled-by-default-v8.cpu_profiler",
    "name": "ProfileChunk",
    "args": {
        "data": {
            "cpuProfile": {
                "nodes": [{
                    "callFrame": {
                        "functionName": "t.load",
                        "url": "https://example.com",
                        "scriptId": 63,
                        "lineNumber": 20,
                        "columnNumber": 19577
                    },
                    "id": 17410,
                    "parent": 17363
                }, {
                    "callFrame": {
                        "functionName": "t.foo",
                        "url": "https://example.com",
                        "scriptId": 63,
                        "lineNumber": 20,
                        "columnNumber": 24832
                    },
                    "id": 17411,
                    "parent": 17410
                }, {
                    "callFrame": {
                        "functionName": "r.get",
                        "url": "https://example.com",
                        "scriptId": 54,
                        "lineNumber": 12,
                        "columnNumber": 8164
                    },
                    "id": 17412,
                    "parent": 17411
                }, {
                    "callFrame": {
                        "functionName": "l",
                        "url": "https://example.com",
                        "scriptId": 54,
                        "lineNumber": 12,
                        "columnNumber": 8680
                    },
                    "id": 17413,
                    "parent": 17412
                }, {
                    "callFrame": {
                        "functionName": "r.bar",
                        "url": "https://example.com",
                        "scriptId": 54,
                        "lineNumber": 12,
                        "columnNumber": 12870
                    },
                    "id": 17414,
                    "parent": 17413
                }, {
                    "callFrame": {
                        "functionName": "An.toJSON.An.valueOf.An.value",
                        "url": "https://example.com",
                        "scriptId": 46,
                        "lineNumber": 1127,
                        "columnNumber": 407
                    },
                    "id": 17415,
                    "parent": 17414
                }, {
                    "callFrame": {
                        "functionName": "wr",
                        "url": "https://example.com",
                        "scriptId": 46,
                        "lineNumber": 1032,
                        "columnNumber": 309
                    },
                    "id": 17416,
                    "parent": 17415
                }, {
                    "callFrame": {
                        "functionName": "l",
                        "url": "https://example.com",
                        "scriptId": 46,
                        "lineNumber": 997,
                        "columnNumber": 457
                    },
                    "id": 17417,
                    "parent": 17416
                }, {
                    "callFrame": {
                        "functionName": "",
                        "url": "https://example.com",
                        "scriptId": 46,
                        "lineNumber": 1032,
                        "columnNumber": 374
                    },
                    "id": 17418,
                    "parent": 17417
                }, {
                    "callFrame": {
                        "functionName": "An.order",
                        "url": "https://example.com",
                        "scriptId": 46,
                        "lineNumber": 1093,
                        "columnNumber": 267
                    },
                    "id": 17419,
                    "parent": 17418
                }, {
                    "callFrame": {
                        "functionName": "Xt",
                        "url": "https://example.com",
                        "scriptId": 46,
                        "lineNumber": 1026,
                        "columnNumber": 476
                    },
                    "id": 17420,
                    "parent": 17419
                }, {
                    "callFrame": {
                        "functionName": "w",
                        "url": "https://example.com",
                        "scriptId": 46,
                        "lineNumber": 999,
                        "columnNumber": 353
                    },
                    "id": 17421,
                    "parent": 17420
                }],
                "samples": [17409, 17409, 17363, 17412, 17412, 17412, 17414, 17421]
            },
            "timeDeltas": [303, 26, 101, 932, 127, 131, 127, 134]
        }
    },
    "tts": 3434306,
    "id": "0x1"
}

我尝试将在配置文件中找到的每个ts值都减去此事件的ts，但是没有一个给我接近8509500微秒的数字。我什至尝试使用"startTime":268810007147值，但是并没有给我带来接近的价值。任何指示如何计算的指针？

谢谢。