From 9a256d34ebca317e3007adf71c2b94016059d4a3 Mon Sep 17 00:00:00 2001 From: Gabriel Schneider Date: Wed, 30 Sep 2026 18:40:41 -0300 Subject: A selection deep in a long line costs a render what one at its start does: 5 MB in, /screen goes from 14.7 s to 5 ms Every render measured a selection's and the cursor's columns from the start of their line (lineDisplayOffset walked the whole prefix twice), so a selection near the end of a 5 MB line stalled each frame, 3 s at 1 MB in and 14.7 s at 5 MB. The cost grew with the offset, with Wrap on or off. Three changes make it independent of where the selection is: - display width adds (a tab is tab_width wherever it stands), so the offset between two columns is the width of the text between them, never the prefix; - the selection's rows are clamped to what is shown: a row wholly before the selection is skipped, a start before the row's first column starts there, and an end past its last column ends there; - a head or cursor whose column lies past its visible row (the last visible row of a line owns every column after its start) is not measured, since it is not drawn. Measured on a Debug build, 5 MB line: offset 10, 1 MB and 5 MB now take 11, 6 and 5 ms per /screen. A new perf gate case, deep-sel, renders with the selection 2 MB into a line: 83 us on Debug. The baselines were re-recorded for the new harness. Co-Authored-By: Claude Opus 5.5 --- test/perf.zig | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) (limited to 'test/perf.zig') diff --git a/test/perf.zig b/test/perf.zig index 95b55748..94076a25 100644 --- a/test/perf.zig +++ b/test/perf.zig @@ -53,6 +53,10 @@ const Op = enum { /// close, as a shell's `>>` loop makes: each costs its own bytes, not a /// pass over the whole body for its cursor, line index and saved hash. body_appends, + /// A render with the selection 2 MB into one line: only the columns + /// shown are measured, so it costs what a selection at the line's + /// start does (4.5 s a frame at 5 MB before). + deep_selection, fn label(o: Op) []const u8 { return switch (o) { @@ -65,6 +69,7 @@ const Op = enum { .edit_char => "edit-char", .body_write => "body-2m", .body_appends => "body-appends", + .deep_selection => "deep-sel", }; } }; @@ -83,6 +88,16 @@ fn bodyWrite(core: *pardes.Pardes, serial: u32) void { _ = core.serveFs(.{ .tag = 4, .op = .release, .node = body, .handle = h, .opened = true }); } +/// One line of 2 MB appended to the file, no newline in it. +fn longLine(core: *pardes.Pardes, serial: u32) void { + const Node = pardes.ctlfs.Node; + const body = Node.of(serial, .body); + @memset(&body_chunk, 'z'); + const h = core.serveFs(.{ .tag = 1, .op = .open, .node = body, .omode = 1 }).handle; + for (0..8) |_| _ = core.serveFs(.{ .tag = 2, .op = .write, .node = body, .handle = h, .data = &body_chunk }); + _ = core.serveFs(.{ .tag = 4, .op = .release, .node = body, .handle = h, .opened = true }); +} + const append_chunk_len = 8 * 1024; const append_count = 64; @@ -534,9 +549,16 @@ fn measure(op: Op, fx: Fixture, path: []const u8, expected_bytes: usize, reps: u core.update(.{ .key = .{ .cp = 'i', .text = "i" } }); pump(core); } + if (op == .deep_selection) { + longLine(core, pane.serial); + pump(core); + const len: u32 = @intCast(pane.file.?.content.len); + pardes.ctlfs.pane.setDot(pane, .{ .q0 = len - 10, .q1 = len - 5 }); + pump(core); + } for (0..warmup + reps) |n| { - seek(pane, fx, n); + if (op != .deep_selection) seek(pane, fx, n); _ = try frame(core); // settle the view at the new spot, untimed const before = .{ .row = pane.body.cur_row, .col = pane.body.cur_col, .scroll = pane.scroll(), .len = pane.file.?.content.len }; const rect = core.rects[id]; @@ -545,7 +567,7 @@ fn measure(op: Op, fx: Fixture, path: []const u8, expected_bytes: usize, reps: u const t0 = nowNs(); switch (op) { .open => unreachable, - .render => {}, + .render, .deep_selection => {}, .key_down => core.update(.{ .key = .{ .cp = 'j', .text = "j" } }), .key_right => core.update(.{ .key = .{ .cp = 'l', .text = "l" } }), .page_down => core.update(.{ .key = .{ .cp = pardes.Key.page_down } }), @@ -561,7 +583,7 @@ fn measure(op: Op, fx: Fixture, path: []const u8, expected_bytes: usize, reps: u .open => unreachable, .body_write => if (pane.file.?.content.len != before.len + 8 * body_chunk.len) return error.BodyWriteWasNotAppended, .body_appends => if (pane.file.?.content.len != before.len + append_count * append_chunk_len) return error.BodyAppendsWereNotAppended, - .render => if (pane.body.cur_row != before.row or pane.body.cur_col != before.col or pane.file.?.content.len != before.len) + .render, .deep_selection => if (pane.body.cur_row != before.row or pane.body.cur_col != before.col or pane.file.?.content.len != before.len) return error.RenderChangedDocument, .key_down => if (pane.body.cur_row != before.row + 1) return error.DownDidNotMove, .key_right => if (pane.body.cur_row != before.row or pane.body.cur_col != before.col + 1) return error.RightDidNotMove, -- cgit v1.3