# git rev-parse -q --verify c8afaa1b0f8bc93d013ab2ea6b9649958af3f1d3^{commit}
c8afaa1b0f8bc93d013ab2ea6b9649958af3f1d3
already have revision, skipping fetch
# git checkout -q -f -B kisskb c8afaa1b0f8bc93d013ab2ea6b9649958af3f1d3
# git clean -qxdf
# < git log -1
# commit c8afaa1b0f8bc93d013ab2ea6b9649958af3f1d3
# Author: Mateusz Guzik <mjguzik@gmail.com>
# Date:   Sat Aug 12 18:15:54 2023 +0200
# 
#     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>
# < /opt/cross/kisskb/korg/gcc-12.2.0-nolibc/mips-linux/bin/mips-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-12.2.0-nolibc/mips-linux/bin/mips-linux-ld --version
# < git log --format=%s --max-count=1 c8afaa1b0f8bc93d013ab2ea6b9649958af3f1d3
# make -s -j 160 ARCH=mips O=/kisskb/build/linus-rand_allnoconfig_mips-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/mips-linux/bin/mips-linux-  allnoconfig
# < make -s -j 160 ARCH=mips O=/kisskb/build/linus-rand_allnoconfig_mips-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/mips-linux/bin/mips-linux-  help
# make -s -j 160 ARCH=mips O=/kisskb/build/linus-rand_allnoconfig_mips-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/mips-linux/bin/mips-linux-  olddefconfig
# make -s -j 160 ARCH=mips O=/kisskb/build/linus-rand_allnoconfig_mips-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/mips-linux/bin/mips-linux-  
Completed OK
# rm -rf /kisskb/build/linus-rand_allnoconfig_mips-gcc12
# Build took: 0:00:23.194938