linux/arch/x86
Mateusz Guzik c8afaa1b0f locking: remove spin_lock_prefetch
The only remaining consumer is new_inode, where it showed up in 2001 as
commit c37fa164f793 ("v2.4.9.9 -> v2.4.9.10") in a historical repo [1]
with a changelog which does not mention it.

Since then the line got only touched up to keep compiling.

While it may have been of benefit back in the day, it is guaranteed to
at best not get in the way in the multicore setting -- as the code
performs *a lot* of work between the prefetch and actual lock acquire,
any contention means the cacheline is already invalid by the time the
routine calls spin_lock().  It adds spurious traffic, for short.

On top of it prefetch is notoriously tricky to use for single-threaded
purposes, making it questionable from the get go.

As such, remove it.

I admit upfront I did not see value in benchmarking this change, but I
can do it if that is deemed appropriate.

Removal from new_inode and of the entire thing are in the same patch as
requested by Linus, so whatever weird looks can be directed at that guy.

Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/fs/inode.c?id=c37fa164f793735b32aa3f53154ff1a7659e6442 [1]
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-08-12 09:18:47 -07:00
..
boot x86/sev: Do not try to parse for the CC blob on non-AMD hardware 2023-08-07 18:05:13 +02:00
coco - Some SEV and CC platform helpers cleanup and simplifications now that 2023-06-27 13:26:30 -07:00
configs arch/*/configs/*defconfig: Replace AUTOFS4_FS by AUTOFS_FS 2023-07-29 14:08:22 -07:00
crypto This push fixes an alignment crash in x86/aria. 2023-05-29 07:05:49 -04:00
entry x86/mm: Fix VDSO and VVAR placement on 5-level paging machines 2023-08-09 13:38:48 -07:00
events perf/x86: Fix lockdep warning in for_each_sibling_event() on SPR 2023-07-10 09:52:20 +02:00
hyperv hyperv-fixes for 6.5-rc5 2023-08-04 17:16:14 -07:00
ia32
include locking: remove spin_lock_prefetch 2023-08-12 09:18:47 -07:00
kernel - Do not parse the confidential computing blob on non-AMD hardware as it 2023-08-12 08:47:01 -07:00
kvm x86: Move gds_ucode_mitigated() declaration to header 2023-08-10 09:13:21 -07:00
lib x86/srso: Add a forgotten NOENDBR annotation 2023-07-29 16:27:17 +02:00
math-emu x86/fpu: Include asm/fpu/regset.h 2023-05-18 11:56:18 -07:00
mm Merge branch 'expand-stack' 2023-06-28 20:35:21 -07:00
net bpf: Fix a bpf_jit_dump issue for x86_64 with sysctl bpf_jit_enable. 2023-06-12 16:47:18 +02:00
pci - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -07:00
platform A single regression fix for x86: 2023-07-01 11:40:01 -07:00
power x86/topology: Remove CPU0 hotplug option 2023-05-15 13:44:49 +02:00
purgatory hardening updates for v6.5-rc1 2023-06-27 21:24:18 -07:00
ras
realmode x86/realmode: Make stack lock work in trampoline_compat() 2023-05-30 14:11:47 +02:00
tools ELF: fix all "Elf" typos 2023-04-08 13:45:37 -07:00
um um: make stub data pages size tweakable 2023-04-20 23:08:43 +02:00
video drm changes for 6.5-rc1: 2023-06-29 11:00:17 -07:00
virt/vmx/tdx
xen xen: branch for v6.5-rc2 2023-07-13 13:39:36 -07:00
.gitignore
Kbuild
Kconfig Mitigate Gather Data Sampling issue 2023-08-07 17:03:54 -07:00
Kconfig.assembler
Kconfig.cpu x86/cpu: Remove X86_FEATURE_NAMES 2023-05-15 20:03:08 +02:00
Kconfig.debug docs: move x86 documentation into Documentation/arch/ 2023-03-30 12:58:51 -06:00
Makefile x86/unwind/orc: Add ELF section with ORC version identifier 2023-06-16 17:17:42 +02:00
Makefile_32.cpu
Makefile.postlink x86/build: Avoid relocation information in final vmlinux 2023-06-14 19:54:40 +02:00
Makefile.um um: Only disable SSE on clang to work around old GCC bugs 2023-04-04 09:57:05 +02:00