sdk/fidl/fuchsia.memory/monitor.fidl

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library fuchsia.memory;

using fuchsia.memorypressure;
using zx;

/// Interface used to register for memory notifications.
@discoverable
protocol Monitor {
    Watch(resource struct {
        watcher client_end:Watcher;
    });

    // Writes to `socket` a JSON capture as a well-formed UTF-8 string.
    WriteJsonCapture(resource struct {
        socket zx.handle:<SOCKET, zx.rights.WRITE | zx.rights.WAIT>;
    });
};

type Stats = struct {
    /// The total amount of physical memory available to the system.
    total_bytes uint64;

    /// The amount of unallocated memory.
    free_bytes uint64;

    /// The amount of memory reserved by and mapped into the kernel for reasons
    /// not covered by other fields in this struct. Typically for readonly data
    /// like the ram disk and kernel image, and for early-boot dynamic memory.
    wired_bytes uint64;

    /// The amount of memory allocated to the kernel heap.
    total_heap_bytes uint64;

    /// The portion of `total_heap_bytes` that is not in use.
    free_heap_bytes uint64;

    /// The amount of memory committed to VMOs, both kernel and user.
    /// A superset of all userspace memory.
    /// Does not include certain VMOs that fall under `wired_bytes`.
    vmo_bytes uint64;

    /// The amount of memory used for architecture-specific MMU metadata
    /// like page tables.
    mmu_overhead_bytes uint64;

    /// The amount of memory in use by IPC.
    ipc_bytes uint64;

    /// Non-free memory that isn't accounted for in any other field.
    other_bytes uint64;
};

/// A watcher for memory changes
protocol Watcher {
    OnChange(struct {
        stats Stats;
    });
};

/// Interface used to debug the singleton memory_monitor instance.
@discoverable
protocol Debugger {
    /// Signals registered watchers of the fuchsia.memorypressure service with
    /// the specified memory pressure level. Intended for debugging only. Does
    /// not affect the real memory pressure level on the system, or trigger any
    /// kernel memory reclamation tasks.
    SignalMemoryPressure(struct {
        level fuchsia.memorypressure.Level;
    });
};