The patch titled
Subject: xarray: inline xas_descend to improve performance
has been added to the -mm mm-unstable branch. Its filename is
xarray-inline-xas_descend-to-improve-performance.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/xarray-inline-xas_descend-to-improve-performance.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Long Li <leo.lilong@xxxxxxxxxx>
Subject: xarray: inline xas_descend to improve performance
Date: Tue, 16 Apr 2024 14:16:28 +0800
The commit 63b1898fffcd ("XArray: Disallow sibling entries of nodes")
modified the xas_descend function in such a way that it was no longer
being compiled as an inline function, because it increased the size of
xas_descend(), and the compiler no longer optimizes it as inline. This
had a negative impact on performance, xas_descend is called frequently to
traverse downwards in the xarray tree, making it a hot function.
Inlining xas_descend has been shown to significantly improve performance
by approximately 4.95% in the iozone write test.
Machine: Intel(R) Xeon(R) Gold 6240 CPU @ 2.60GHz
#iozone i 0 -i 1 -s 64g -r 16m -f /test/tmptest
Before this patch:
kB reclen write rewrite read reread
67108864 16384 2230080 3637689 6315197 5496027
After this patch:
kB reclen write rewrite read reread
67108864 16384 2340360 3666175 6272401 5460782
Percentage change:
4.95% 0.78% -0.68% -0.64%
This patch introduces inlining to the xas_descend function. While this
change increases the size of lib/xarray.o, the performance gains in
critical workloads make this an acceptable trade-off.
Size comparison before and after patch:
text .data .bss file
0x3502 0 0 lib/xarray.o.before
0x3602 0 0 lib/xarray.o.after
Link: https://lkml.kernel.org/r/20240416061628.3768901-1-leo.lilong@xxxxxxxxxx
Signed-off-by: Long Li <leo.lilong@xxxxxxxxxx>
Cc: Hou Tao <houtao1@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: yangerkun <yangerkun@xxxxxxxxxx>
Cc: Zhang Yi <yi.zhang@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/xarray.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/lib/xarray.c~xarray-inline-xas_descend-to-improve-performance
+++ a/lib/xarray.c
@@ -200,7 +200,8 @@ static void *xas_start(struct xa_state *
return entry;
}
-static void *xas_descend(struct xa_state *xas, struct xa_node *node)
+static __always_inline void *xas_descend(struct xa_state *xas,
+ struct xa_node *node)
{
unsigned int offset = get_offset(xas->xa_index, node);
void *entry = xa_entry(xas->xa, node, offset);
_
Patches currently in -mm which might be from leo.lilong@xxxxxxxxxx are
xarray-inline-xas_descend-to-improve-performance.patch
