Boyan Karatotev 89dba82dfa perf(cpus): make reset errata do fewer branches ... Errata application is painful for performance. For a start, it's done when the core has just come out of reset, which means branch predictors and caches will be empty so a branch to a workaround function must be fetched from memory and that round trip is very slow. Then it also runs with the I-cache off, which means that the loop to iterate over the workarounds must also be fetched from memory on each iteration. We can remove both branches. First, we can simply apply every erratum directly instead of defining a workaround function and jumping to it. Currently, no errata that need to be applied at both reset and runtime, with the same workaround function, exist. If the need arose in future, this should be achievable with a reset + runtime wrapper combo. Then, we can construct a function that applies each erratum linearly instead of looping over the list. If this function is part of the reset function, then the only "far" branches at reset will be for the checker functions. Importantly, this mitigates the slowdown even when an erratum is disabled. The result is ~50% speedup on N1SDP and ~20% on AArch64 Juno on wakeup from PSCI calls that end in powerdown. This is roughly back to the baseline of v2.9, before the errata framework regressed on performance (or a little better). It is important to note that there are other slowdowns since then that remain unknown. Change-Id: Ie4d5288a331b11fd648e5c4a0b652b74160b07b9 Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>		2025-02-24 09:36:11 +00:00
..
alt-boot-flows.rst	doc: Split the User Guide into multiple files	2019-11-27 10:45:54 +00:00
auth-framework.rst	docs(auth): extrapolate on the functions within a CM	2024-12-09 14:00:33 +00:00
console-framework.rst	docs(console): updated console docs	2025-02-12 10:18:57 +00:00
cpu-specific-build-macros.rst	fix(cpus): fix a typo in errata doc	2025-02-19 09:37:35 -06:00
firmware-design.rst	perf(cpus): make reset errata do fewer branches	2025-02-24 09:36:11 +00:00
index.rst	docs(console): updated console docs	2025-02-12 10:18:57 +00:00
interrupt-framework-design.rst	Fix broken links to various sections across docs	2020-08-03 09:55:04 -05:00
psci-pd-tree.rst	doc: Set correct syntax highlighting style	2019-05-22 11:28:17 +01:00
reset-design.rst	docs: update RESET_TO_BL31 documentation	2023-03-09 14:42:49 +00:00
trusted-board-boot-build.rst	docs(arm): update docs to reflect rotpk key changes	2024-12-30 12:32:22 +01:00
trusted-board-boot.rst	docs(arm): update docs to reflect rotpk key changes	2024-12-30 12:32:22 +01:00