https://github.com/da-viper updated https://github.com/llvm/llvm-project/pull/182011
>From cbf20d3fa92d7c0cc239f885fa8914fc2fea8f2a Mon Sep 17 00:00:00 2001 From: Ebuka Ezike <[email protected]> Date: Wed, 18 Feb 2026 11:25:35 +0000 Subject: [PATCH 1/2] [lldb] Fix Linux memory monitor. Only call the callback when we are actually low on memory. Increase the threshold to 200ms in a 2 second interval to match systemd's default see [DefaultMemoryPressureWatch](https://www.freedesktop.org/software/systemd/man/latest/systemd-system.conf.html#DefaultMemoryPressureWatch=). --- lldb/source/Host/common/MemoryMonitor.cpp | 48 ++++++++++++++++++++--- 1 file changed, 43 insertions(+), 5 deletions(-) diff --git a/lldb/source/Host/common/MemoryMonitor.cpp b/lldb/source/Host/common/MemoryMonitor.cpp index 7734be8688675..82b5356c9983b 100644 --- a/lldb/source/Host/common/MemoryMonitor.cpp +++ b/lldb/source/Host/common/MemoryMonitor.cpp @@ -18,6 +18,8 @@ #include <cstring> #if defined(__linux__) +#include "lldb/Host/posix/Support.h" +#include "llvm/Support/LineIterator.h" #include <fcntl.h> #include <poll.h> #include <sys/eventfd.h> @@ -44,7 +46,7 @@ class MemoryMonitorLinux : public MemoryMonitor { ~MemoryMonitorLinux() { if (m_memory_monitor_thread.IsJoinable()) m_memory_monitor_thread.Join(nullptr); - if (m_stop_fd != 1) + if (m_stop_fd != -1) ::close(m_stop_fd); } @@ -96,8 +98,8 @@ class MemoryMonitorLinux : public MemoryMonitor { llvm::scope_exit cleanup([&]() { ::close(pfds[pressure_idx].fd); }); - // Detect a 50ms stall in a 2 second time window. - constexpr llvm::StringRef trigger = "some 50000 2000000"; + // Detect a 200ms stall in a 2 second time window. + constexpr llvm::StringRef trigger = "some 200000 2000000"; if (::write(pfds[pressure_idx].fd, trigger.data(), trigger.size() + 1) < 0) return {}; @@ -109,14 +111,50 @@ class MemoryMonitorLinux : public MemoryMonitor { if (pfds[stop_idx].revents & (POLLIN | POLLERR)) return {}; - if (pfds[pressure_idx].revents & POLLERR) + const short pressure_revents = pfds[stop_idx].revents; + if (pressure_revents & POLLERR) return {}; - if (pfds[pressure_idx].revents & POLLPRI) + if ((pressure_revents & POLLPRI) && isLowMemory()) m_callback(); } } return {}; } + + static bool isLowMemory() { + llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> bufferOrErr = + getProcFile("meminfo"); + + if (!bufferOrErr) + return false; + + uint64_t mem_total = 0; + uint64_t mem_available = 0; + const int radix = 10; + + for (llvm::line_iterator iter(**bufferOrErr, true); !iter.is_at_end(); + ++iter) { + llvm::StringRef line = *iter; + if (line.consume_front("MemTotal:")) { + line.ltrim().consumeInteger(radix, mem_total); + continue; + } + + if (line.consume_front("MemAvailable:")) { + line.ltrim().consumeInteger(radix, mem_available); + // MemAvailable comes after MemTotal. + break; + } + } + + if (mem_total == 0 || mem_available == 0) + return false; + + const uint64_t approx_memory_percent = (mem_available * 100) / mem_total; + const uint64_t low_memory_percent = 20; + return approx_memory_percent < low_memory_percent; + } + int m_stop_fd = -1; HostThread m_memory_monitor_thread; }; >From 942526aa6939f3001dab56f63a934ef8181ea5ca Mon Sep 17 00:00:00 2001 From: Ebuka Ezike <[email protected]> Date: Wed, 18 Feb 2026 15:24:59 +0000 Subject: [PATCH 2/2] add review changes --- lldb/source/Host/common/MemoryMonitor.cpp | 27 ++++++++++++----------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/lldb/source/Host/common/MemoryMonitor.cpp b/lldb/source/Host/common/MemoryMonitor.cpp index 82b5356c9983b..49e568aa26590 100644 --- a/lldb/source/Host/common/MemoryMonitor.cpp +++ b/lldb/source/Host/common/MemoryMonitor.cpp @@ -114,41 +114,42 @@ class MemoryMonitorLinux : public MemoryMonitor { const short pressure_revents = pfds[stop_idx].revents; if (pressure_revents & POLLERR) return {}; - if ((pressure_revents & POLLPRI) && isLowMemory()) - m_callback(); + if (pressure_revents & POLLPRI) { + if (const std::optional<bool> is_low_opt = IsLowMemory(); + is_low_opt && *is_low_opt) + m_callback(); + } } } return {}; } - static bool isLowMemory() { - llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> bufferOrErr = + static std::optional<bool> IsLowMemory() { + llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> buffer_or_err = getProcFile("meminfo"); - if (!bufferOrErr) - return false; + if (!buffer_or_err) + return std::nullopt; uint64_t mem_total = 0; uint64_t mem_available = 0; const int radix = 10; - for (llvm::line_iterator iter(**bufferOrErr, true); !iter.is_at_end(); + for (llvm::line_iterator iter(**buffer_or_err, true); !iter.is_at_end(); ++iter) { llvm::StringRef line = *iter; if (line.consume_front("MemTotal:")) { line.ltrim().consumeInteger(radix, mem_total); - continue; + } else if (line.consume_front("MemAvailable:")) { + line.ltrim().consumeInteger(radix, mem_available); } - if (line.consume_front("MemAvailable:")) { - line.ltrim().consumeInteger(radix, mem_available); - // MemAvailable comes after MemTotal. + if (mem_total && mem_available) break; - } } if (mem_total == 0 || mem_available == 0) - return false; + return std::nullopt; const uint64_t approx_memory_percent = (mem_available * 100) / mem_total; const uint64_t low_memory_percent = 20; _______________________________________________ lldb-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
