Name the game's frame-rate ceiling as a period of its own, frame_step_ceiling_ns, for a pacer that hands the limit over.

When Reflex holds the frame limit with DLSS Frame Generation, the game's pacer is to keep only the rate the game's
code survives (240 a second; the quick menu read address 0 at 640 to 700), so that a limiter that lets go, or one
that counts other frames than the game's, cannot run the game past it. frame_step_ceiling_ns gives that period
from LIMIT_FREE_MAX_HZ, or LIMIT_MAX_HZ for a build with the fps60 or realtime patch set; frame_step_cap_ns is left
as it is. tests/frame_step_check.c checks 4166666 ns for a game stepping by the clock; frame_step_check passes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/frame_step_check.c

@@ -182,6 +182,9 @@ int main(int argc, char **argv) {
     int mean = argc > 1 && !strcmp(argv[1], "mean");
     if (mean) steady = "0";
     frame_step_init();
+    // the pacer's period while Reflex holds the limit (vk_dlssg.c vk_dlssg_pace): 240 fps for a game stepping by the clock
+    CHECK(frame_step_ceiling_ns() == 4166666, "the ceiling of a game that steps by the clock: %llu ns",
+          (unsigned long long)frame_step_ceiling_ns());
     float one, cut0;
     memcpy(&one, page + 256, 4);
     memcpy(&cut0, page + 260, 4);