posix_memalign performance regression in 2.38?

[Xi Ruoyao]

Hi,

There seems a performance regression of posix_memalign in Glibc-2.38:

$ cat t.c
#include <stdlib.h>
int main()
{
	void *buf;
	for (int i = 0; i < (1 << 16); i++)
		posix_memalign(&buf, 64, 16);
}
$ cc t.c
$ time ./a.out 

real	0m0.008s
user	0m0.005s
sys	0m0.003s
$ time ~/sources/lfs/glibc-2.38/build/testrun.sh ./a.out 

real	0m4.376s
user	0m4.369s
sys	0m0.007s

The behavior seems worse than quadratic: if I change "1 << 16" to "1 <<
17", I get:

$ time ~/sources/lfs/glibc-2.38/build/testrun.sh ./a.out 

real	0m28.597s
user	0m28.568s
sys	0m0.022s

I've not bisected for this yet.

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University