Make rgw use tcmalloc/jemalloc

Hi folks, How could I make rgw built with tcmalloc/jemalloc? I had tcmalloc installed. Although build.ninja has libtcmalloc.so listed for bin/radosgw, it is still using libc’s malloc. Then I had jemalloc installed and the result is the same. What is the proper step to make rgw built with tcmalloc/jemalloc? Thanks Yixin