linux/arch/ia64
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
..
configs arch/*/configs/*defconfig: Replace AUTOFS4_FS by AUTOFS_FS 2023-07-29 14:08:22 -07:00
hp/common ACPI: make remove callback of ACPI driver void 2022-11-23 19:11:22 +01:00
include locking: remove spin_lock_prefetch 2023-08-12 09:18:47 -07:00
kernel io_uring-6.5-2023-07-21 2023-07-22 10:46:30 -07:00
lib Merge branch 'work.csum_and_copy' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-12 16:24:13 -07:00
mm Merge branch 'expand-stack' 2023-06-28 20:35:21 -07:00
pci docs: move ia64 architecture docs under Documentation/arch/ 2023-04-10 16:45:52 -06:00
scripts kbuild: remove PYTHON variable 2021-02-01 10:37:19 +09:00
uv ia64: remove support for machvecs 2019-08-16 14:32:26 -07:00
install.sh kbuild: factor out the common installation code into scripts/install.sh 2022-05-11 21:45:53 +09:00
Kbuild ia64: move core-y in arch/ia64/Makefile to arch/ia64/Kbuild 2021-09-03 08:17:20 +09:00
Kconfig ia64/cpu: Switch to arch_cpu_finalize_init() 2023-06-16 10:15:59 +02:00
Kconfig.debug ia64: don't do IA64_CMPXCHG_DEBUG without CONFIG_PRINTK 2021-10-04 10:45:58 +02:00
Makefile arch: Introduce CONFIG_FUNCTION_ALIGNMENT 2022-10-17 16:40:58 +02:00