ci: Use a RAM disk for NetBSD and OpenBSD.

Put the RAM disk setup for all three *BSD CI tasks into a common script,
replacing the old FreeBSD-specific one from commit 0265e5c1.  This makes
them run 3 times and a bit over 2 times faster, respectively.

NetBSD and FreeBSD now share the same one-liner to mount tmpfs.  OpenBSD
needs a GCP-image specific recipe that knows where to steal an unused
disk partition needed to reserve swap space for an mfs RAM disk, because
its tmpfs is deprecated and currently broken.  The configured size is
enough for our current tests but could potentially need future
expansion.  Thanks to Bilal for the disklabel incantation.

Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGJJ-XrPhN%2BQA4ZUfYAAXcwOSDty9t0vE9Z8__AdacKnQg%40mail.gmail.com

.cirrus.tasks.yml

@@ -155,8 +155,7 @@ task:
 
   ccache_cache:
     folder: $CCACHE_DIR
-  # Work around performance issues due to 32KB block size
-  repartition_script: src/tools/ci/gcp_freebsd_repartition.sh
+  setup_ram_disk_script: src/tools/ci/gcp_ram_disk.sh
   create_user_script: |
     pw useradd postgres
     chown -R postgres:postgres .
@@ -276,7 +275,7 @@ task:
 
   ccache_cache:
     folder: $CCACHE_DIR
-
+  setup_ram_disk_script: src/tools/ci/gcp_ram_disk.sh
   create_user_script: |
     useradd postgres
     chown -R postgres:users /home/postgres

src/tools/ci/gcp_freebsd_repartition.sh

@@ -1,26 +0,0 @@
-#!/bin/sh
-
-set -e
-set -x
-
-# fix backup partition table after resize
-gpart recover da0
-gpart show da0
-
-# delete and re-add swap partition with expanded size
-swapoff -a
-gpart delete -i 3 da0
-gpart add -t freebsd-swap -l swapfs -a 4096 da0
-gpart show da0
-swapon -a
-
-# create a file system on a memory disk backed by swap, to minimize I/O
-mdconfig -a -t swap -s20g -u md1
-newfs -b 8192 -U /dev/md1
-
-# migrate working directory
-du -hs $CIRRUS_WORKING_DIR
-mv $CIRRUS_WORKING_DIR $CIRRUS_WORKING_DIR.orig
-mkdir $CIRRUS_WORKING_DIR
-mount -o noatime /dev/md1 $CIRRUS_WORKING_DIR
-cp -a $CIRRUS_WORKING_DIR.orig/ $CIRRUS_WORKING_DIR/

src/tools/ci/gcp_ram_disk.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+# Move working directory into a RAM disk for better performance.
+
+set -e
+set -x
+
+mv $CIRRUS_WORKING_DIR $CIRRUS_WORKING_DIR.orig
+mkdir $CIRRUS_WORKING_DIR
+
+case "`uname`" in
+  FreeBSD|NetBSD)
+    mount -t tmpfs tmpfs $CIRRUS_WORKING_DIR
+    ;;
+  OpenBSD)
+    umount /dev/sd0j # unused /usr/obj partition
+    printf "m j\n\n\nswap\nw\nq\n" | disklabel -E sd0
+    swapon /dev/sd0j
+    mount -t mfs -o rw,noatime,nodev,-s=8000000 swap $CIRRUS_WORKING_DIR
+    ;;
+esac
+
+cp -a $CIRRUS_WORKING_DIR.orig/. $CIRRUS_WORKING_DIR/