maillist inclusion category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/I9HBUZ CVE: NA Reference: https://lkml.kernel.org/r/20240416061628.3768901-1-leo.lilong@huawei.com -------------------------------- 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 Signed-off-by: Long Li <leo.lilong@huawei.com> --- lib/xarray.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/xarray.c b/lib/xarray.c index 39f07bfc4dcc..f49053882354 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -200,7 +200,8 @@ static void *xas_start(struct xa_state *xas) 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); -- 2.31.1