1f49714d3e
This diffs implements per-core tracing on lldb-server. It also includes tests that ensure that tracing can be initiated from the client and that the jLLDBGetState ppacket returns the list of trace buffers per core. This doesn't include any decoder changes. Finally, this makes some little changes here and there improving the existing code. A specific piece of code that can't reliably be tested is when tracing per core fails due to permissions. In this case we add a troubleshooting message and this is the manual test: ``` /proc/sys/kernel/perf_event_paranoid set to 1 (lldb) process trace start --per-core-tracing error: perf event syscall failed: Permission denied You might need that /proc/sys/kernel/perf_event_paranoid has a value of 0 or -1. `` Differential Revision: https://reviews.llvm.org/D124858
73 lines
2.5 KiB
C++
73 lines
2.5 KiB
C++
//===-- Procfs.cpp --------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "Procfs.h"
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#include "lldb/Host/linux/Support.h"
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#include "llvm/Support/MemoryBuffer.h"
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using namespace lldb;
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using namespace lldb_private;
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using namespace process_linux;
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using namespace llvm;
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Expected<ArrayRef<uint8_t>> lldb_private::process_linux::GetProcfsCpuInfo() {
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static Optional<std::vector<uint8_t>> cpu_info;
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if (!cpu_info) {
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auto buffer_or_error = errorOrToExpected(getProcFile("cpuinfo"));
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if (!buffer_or_error)
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return buffer_or_error.takeError();
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MemoryBuffer &buffer = **buffer_or_error;
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cpu_info = std::vector<uint8_t>(
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reinterpret_cast<const uint8_t *>(buffer.getBufferStart()),
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reinterpret_cast<const uint8_t *>(buffer.getBufferEnd()));
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}
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return *cpu_info;
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}
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Expected<std::vector<core_id_t>>
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lldb_private::process_linux::GetAvailableLogicalCoreIDs(StringRef cpuinfo) {
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SmallVector<StringRef, 8> lines;
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cpuinfo.split(lines, "\n", /*MaxSplit=*/-1, /*KeepEmpty=*/false);
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std::vector<core_id_t> logical_cores;
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for (StringRef line : lines) {
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std::pair<StringRef, StringRef> key_value = line.split(':');
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auto key = key_value.first.trim();
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auto val = key_value.second.trim();
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if (key == "processor") {
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core_id_t processor;
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if (val.getAsInteger(10, processor))
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return createStringError(
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inconvertibleErrorCode(),
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"Failed parsing the /proc/cpuinfo line entry: %s", line.data());
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logical_cores.push_back(processor);
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}
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}
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return logical_cores;
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}
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llvm::Expected<llvm::ArrayRef<core_id_t>>
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lldb_private::process_linux::GetAvailableLogicalCoreIDs() {
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static Optional<std::vector<core_id_t>> logical_cores_ids;
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if (!logical_cores_ids) {
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// We find the actual list of core ids by parsing /proc/cpuinfo
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Expected<ArrayRef<uint8_t>> cpuinfo = GetProcfsCpuInfo();
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if (!cpuinfo)
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return cpuinfo.takeError();
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Expected<std::vector<core_id_t>> core_ids = GetAvailableLogicalCoreIDs(
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StringRef(reinterpret_cast<const char *>(cpuinfo->data())));
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if (!core_ids)
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return core_ids.takeError();
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logical_cores_ids.emplace(std::move(*core_ids));
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}
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return *logical_cores_ids;
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}
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