AMD has disabled the Loop Buffer feature in its Ryzen 7000 series processors via a recent microcode update. This article explores the implications of this change for users and its impact on performance.
The Loop Buffer was a dedicated storage area for repetitive CPU instructions, designed to reduce the need to access cache memory during looping operations. AMD introduced this feature exclusively for Zen 4 architecture processors but has now removed it. Reports suggest that software developers never fully utilized the Loop Buffer's potential due to a lack of detailed documentation and the already ample cache capacity and bandwidth of Zen 4 chips.
The change was first noticed by users on Chips and Cheese, who observed the "downgrade" in the Ryzen 9 7950X3D. The Loop Buffer was present in AGESA firmware version 1.0.0.6 but absent in version 1.2.0.2a.
Performance tests indicate a minimal impact on overall CPU capabilities. The loss in processing power is estimated at around 1% for integer and floating-point operations. Non-3D V-Cache processors experienced a slightly larger performance drop, up to 5%, in the game Cyberpunk 2077.
