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authorMateusz Guzik <mjguzik@gmail.com>2023-08-12 18:15:54 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2023-08-12 09:18:47 -0700
commitc8afaa1b0f8bc93d013ab2ea6b9649958af3f1d3 (patch)
treecdf2d4c2f22ab40d7d31ba99ffdce18e3dfcc6cd /fs
parent3feecb1b848359b152dd66b26c24c2454a64fc15 (diff)
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/inode.c3
1 files changed, 0 insertions, 3 deletions
diff --git a/fs/inode.c b/fs/inode.c
index 8fefb69e1f84..67611a360031 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -16,7 +16,6 @@
#include <linux/fsnotify.h>
#include <linux/mount.h>
#include <linux/posix_acl.h>
-#include <linux/prefetch.h>
#include <linux/buffer_head.h> /* for inode_has_buffers */
#include <linux/ratelimit.h>
#include <linux/list_lru.h>
@@ -1041,8 +1040,6 @@ struct inode *new_inode(struct super_block *sb)
{
struct inode *inode;
- spin_lock_prefetch(&sb->s_inode_list_lock);
-
inode = new_inode_pseudo(sb);
if (inode)
inode_sb_list_add(inode);