tiny.mprompt.Config

1/// Holds the runtime's tuning values with a C layout, and every field has a default. A program that2/// needs larger stacks, another pool size, or fully committed stacks passes one to `init` before it3/// creates any prompt. The runtime reads it once, at initialization, and later changes have no4/// effect. Sizes are in bytes and are rounded up to whole pages. A size of zero or less selects the5/// field's default. `configDefault` returns one with every default.6pub const Config = extern struct {7    /// When true, each stacklet comes from shared reserved regions cut into equal stacklet-sized8    /// blocks (stack pool). When false, each stacklet reserves its own range of address space. The9    /// default is true, and overcommit mode turns it off. Every thread of the process takes10    /// stacklets from the pool under one lock.11    gpool_enable: bool = true,12    /// When true, the runtime's fault handler commits extra pages past the faulting page each time13    /// a write faults in the uncommitted part of a stacklet. The extra space is twice the stack in14    /// use so far, at most 1 MiB, and at most the space left. When false, the runtime commits pages15    /// up to the faulting page only. The runtime commits a page by making it readable and writable.16    /// The default is true, and overcommit mode turns it off.17    stack_grow_fast: bool = true,18    /// When true, the runtime commits every page of a stacklet when it takes the stacklet, and it19    /// installs no fault handler and no alternate signal stack. Turning it on also turns off the20    /// stack pool and fast growth. The default is false.21    stack_use_overcommit: bool = false,22    /// When true, the runtime makes every page of a stacklet inaccessible when it places the23    /// stacklet in a per-thread list of freed stacklets and prompt records for reuse (stack cache),24    /// and it also decommits the used pages of a pooled stacklet it frees. When false, a cached25    /// stacklet keeps its pages, and a pooled stacklet that is freed has its used pages discarded,26    /// so their contents are dropped. The default is false.27    stack_reset_decommits: bool = false,28    /// The size in bytes of each region of the stack pool. A region holds as many stacklets as fit29    /// in this size, at least 1 and at most 32,000. The process reserves another region when every30    /// block of the existing ones is in use. The default is 256 GiB of address space.31    gpool_max_size: isize = 256 * gib,32    /// The reserved size of each stacklet in bytes, the two gaps included, so the usable stack is33    /// this size minus twice `stack_gap_size`. The default is 8 MiB. Initialization stops the34    /// program with a panic when the size leaves one page or less of usable stack. A write past the35    /// usable stack lands in a gap, which the runtime never commits, so the fault goes to the36    /// program's earlier fault handler, or the process aborts when there was none.37    stack_max_size: isize = 8 * mib,38    /// The runtime reads nothing from this field, so its value has no effect. The default is 3239    /// KiB.40    stack_exn_guaranteed: isize = 32 * kib,41    /// The number of bytes of a new stacklet committed when the runtime takes it, rounded up to42    /// whole pages. The default of 0 means one page. The runtime caps it at the stacklet's usable43    /// size.44    stack_initial_commit: isize = 0,45    /// The size in bytes of the unmapped gap at each end of a stacklet, rounded up to whole pages.46    /// The default is 64 KiB.47    stack_gap_size: isize = 64 * kib,48    /// The number of freed stacklets, and separately the number of freed prompt records, that each49    /// thread keeps for reuse. The default is 4. A negative value becomes 0, which turns the reuse50    /// off.51    stack_cache_count: isize = 4,52};

1pub const Config = raw.Config;