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ke: optimize IPL operations

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Loïc Grégoire
2026-08-07 15:41:12 -04:00
parent 5bb264a9ae
commit 52f62b8354
5 changed files with 105 additions and 46 deletions
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src/kern/ipl.zig
+49 -34
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@@ -20,77 +20,85 @@ pub const Ipl = enum(u8) {
};
const PerCpu = struct {
/// Current IPL on this CPU.
ipl: Ipl,
/// Bitmask of pending software interrupts on this CPU.
pending_softints: std.atomic.Value(u8),
};
/// Current IPL on this CPU.
pub const cpu_ipl = ke.ExportedCpuLocal(
Ipl,
.Passive,
"cpu_ipl",
);
pub const percpu = ke.CpuLocal(PerCpu, .{
.ipl = .Passive,
.pending_softints = std.atomic.Value(u8).init(0),
.pending_softints = .init(0),
});
pub fn current() Ipl {
return percpu.local().ipl;
return cpu_ipl.local().*;
}
/// Raise IPL to `new`.
/// Panics if the current IPL is higher than requested.
pub fn raise(new: Ipl) Ipl {
const ints = ki.impl.disable_interrupts();
var old: ke.Ipl = undefined;
var cpu = percpu.local();
const old = cpu.ipl;
if (@intFromEnum(new) < @intFromEnum(old)) {
std.debug.panic("ke.ipl.raise(): Target IPL ({}) is lower than current IPL ({})", .{ new, old });
if (ki.impl.raise_software_ipl(new, &old)) {
@branchHint(.unlikely);
std.debug.panic(
"ke.ipl.raise(): Target IPL ({}) is lower than current IPL ({})",
.{ new, old },
);
}
if (@intFromEnum(new) > @intFromEnum(Ipl.get_max_software())) {
// Moving between hardware levels is rare.
@branchHint(.unlikely);
ki.impl.set_hardware_ipl(new);
}
cpu.ipl = new;
ki.impl.restore_interrupts(ints);
return old;
}
/// Lower IPL to `new`.
/// Panics if the current IPL is lower than requested.
pub fn lower(new: Ipl) void {
const ints = ki.impl.disable_interrupts();
var cpu = percpu.local();
const cpu_id = ke.cpu.current();
const old = cpu.ipl;
var old: ke.Ipl = undefined;
if (@intFromEnum(new) > @intFromEnum(old)) {
std.debug.panic("ke.ipl.lower(): Target IPL ({}) is higher than current IPL ({})", .{ new, old });
if (ki.impl.lower_software_ipl(new, &old)) {
@branchHint(.unlikely);
std.debug.panic(
"ke.ipl.lower(): Target IPL ({}) is higher than current IPL ({})",
.{ new, old },
);
}
if (@intFromEnum(new) <= @intFromEnum(Ipl.get_max_software()) and @intFromEnum(old) > @intFromEnum(Ipl.get_max_software())) {
if (@intFromEnum(new) <= @intFromEnum(Ipl.get_max_software()) and
@intFromEnum(old) > @intFromEnum(Ipl.get_max_software()))
{
@branchHint(.unlikely);
ki.impl.set_hardware_ipl(.Passive);
}
cpu.ipl = new;
ki.impl.restore_interrupts(ints);
if (@intFromEnum(new) < @intFromEnum(Ipl.Dispatch) and is_softint_pending(.Dispatch)) {
ki.dpc.dispatch(cpu_id);
if (@intFromEnum(new) < @intFromEnum(Ipl.Dispatch) and
is_softint_pending(.Dispatch))
{
// Dispatch DPCs if necessary.
ki.dpc.dispatch();
}
}
/// Set the hardware IPL to `new`.
pub fn set_hardware(new: Ipl) Ipl {
var cpu = percpu.local();
const old = cpu.ipl;
const ints = ki.impl.disable_interrupts();
const cpu = cpu_ipl.local();
const old = cpu.*;
cpu.ipl = new;
cpu.* = new;
ki.impl.set_hardware_ipl(new);
ki.impl.restore_interrupts(ints);
return old;
}
@@ -98,16 +106,23 @@ pub fn set_hardware(new: Ipl) Ipl {
/// Mark a software interrupt of IPL `ipl` on `cpu` as pending.
pub fn set_softint_pending(cpu: u32, ipl: Ipl) void {
std.debug.assert(@intFromEnum(ipl) <= @intFromEnum(Ipl.Dispatch));
_ = percpu.remote(cpu).pending_softints.bitSet(@intCast(@intFromEnum(ipl)), .monotonic);
_ = percpu.remote(cpu).pending_softints.bitSet(
@intCast(@intFromEnum(ipl)),
.monotonic,
);
}
/// Mark a software interrupt of IPL `ipl` on `cpu` as handled.
pub fn clear_softint_pending(cpu: u32, ipl: Ipl) void {
std.debug.assert(@intFromEnum(ipl) <= @intFromEnum(Ipl.Dispatch));
_ = percpu.remote(cpu).pending_softints.bitReset(@intCast(@intFromEnum(ipl)), .monotonic);
_ = percpu.remote(cpu).pending_softints.bitReset(
@intCast(@intFromEnum(ipl)),
.monotonic,
);
}
/// Check whether a software interrupt of IPL `ipl` on the current CPU is pending.
/// Check whether a software interrupt of IPL `ipl`
/// is pending on the current CPU.
pub fn is_softint_pending(ipl: Ipl) bool {
std.debug.assert(@intFromEnum(ipl) <= @intFromEnum(Ipl.Dispatch));
const shift: u3 = @intCast(@intFromEnum(ipl));