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Diffstat (limited to '')
-rw-r--r-- | hal/linux/LinuxProcessPriority.cpp | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/hal/linux/LinuxProcessPriority.cpp b/hal/linux/LinuxProcessPriority.cpp new file mode 100644 index 0000000000..a0f72a4f38 --- /dev/null +++ b/hal/linux/LinuxProcessPriority.cpp @@ -0,0 +1,78 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this file, + * You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "Hal.h" +#include "HalLog.h" + +#include "mozilla/Sprintf.h" +#include "mozilla/Unused.h" + +#include <fcntl.h> +#include <unistd.h> + +using namespace mozilla::hal; + +namespace mozilla::hal_impl { + +/* The Linux OOM score is a value computed by the kernel ranging between 0 and + * 1000 and indicating how likely is a process to be killed when memory is + * tight. The larger the value the more likely a process is to be killed. The + * score is computed based on the amount of memory used plus an adjustment + * value. We chose our adjustment values to make it likely that processes are + * killed in the following order: + * + * 1. preallocated processes + * 2. background processes + * 3. background processes playing video (but no audio) + * 4. foreground processes or processes playing or recording audio + * 5. the parent process + * + * At the time of writing (2022) the base score for a process consuming very + * little memory seems to be around ~667. Our adjustments are thus designed + * to ensure this order starting from a 667 baseline but trying not to go too + * close to the 1000 limit where they would be clamped. */ + +const uint32_t kParentOomScoreAdjust = 0; +const uint32_t kForegroundOomScoreAdjust = 100; +const uint32_t kBackgroundPerceivableOomScoreAdjust = 133; +const uint32_t kBackgroundOomScoreAdjust = 167; +const uint32_t kPreallocOomScoreAdjust = 233; + +static uint32_t OomScoreAdjForPriority(ProcessPriority aPriority) { + switch (aPriority) { + case PROCESS_PRIORITY_BACKGROUND: + return kBackgroundOomScoreAdjust; + case PROCESS_PRIORITY_BACKGROUND_PERCEIVABLE: + return kBackgroundPerceivableOomScoreAdjust; + case PROCESS_PRIORITY_PREALLOC: + return kPreallocOomScoreAdjust; + case PROCESS_PRIORITY_FOREGROUND: + return kForegroundOomScoreAdjust; + default: + return kParentOomScoreAdjust; + } +} + +void SetProcessPriority(int aPid, ProcessPriority aPriority) { + HAL_LOG("LinuxProcessPriority - SetProcessPriority(%d, %s)\n", aPid, + ProcessPriorityToString(aPriority)); + + uint32_t oomScoreAdj = OomScoreAdjForPriority(aPriority); + + char path[32] = {}; + SprintfLiteral(path, "/proc/%d/oom_score_adj", aPid); + + char oomScoreAdjStr[11] = {}; + SprintfLiteral(oomScoreAdjStr, "%d", oomScoreAdj); + + int fd = open(path, O_WRONLY); + if (fd < 0) { + return; + } + const size_t len = strlen(oomScoreAdjStr); + Unused << write(fd, oomScoreAdjStr, len); + Unused << close(fd); +} + +} // namespace mozilla::hal_impl |