build perf more directly so we can pass -s

diff --git a/do_build b/do_build
index 20c3478120abfa104a89878520864981a8b8e0cc..63f3bdfc67d9ca8814294c8729c2e421bbc35720 100755 (executable)
--- a/do_build
+++ b/do_build
@@ -123,7 +123,7 @@ $cmd <<-EOF
        [ -d \$d ] || mkdir \$d || exit 1
        log_perf=\$d.log
        echo "Forking perf build ..."
-       /usr/bin/time make -s -O -C tools/perf JOBS="$j_factor" O=\$d > \$log_perf 2>&1 &
+       /usr/bin/time make -C tools/perf -f Makefile.perf -s -O -j"$j_factor" O=\$d > \$log_perf 2>&1 &
        perf_pid=\$!
 
        wait \$perf_pid