ZTS: Optimize KSM on Linux and remove it for FreeBSD

Don't use KSM on the FreeBSD VMs and optimize KSM settings for
Linux to have faster run times.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #17247

.github/workflows/scripts/qemu-6-tests.sh

@@ -45,7 +45,7 @@ if [ -z ${1:-} ]; then
   echo 0 > /tmp/ctr
   date "+%s" > /tmp/tsstart
 
-  for i in $(seq 1 $VMs); do
+  for ((i=1; i<=VMs; i++)); do
     IP="192.168.122.1$i"
     daemonize -c /var/tmp -p vm${i}.pid -o vm${i}log.txt -- \
       $SSH zfs@$IP $TESTS $OS $i $VMs $CI_TYPE
@@ -58,7 +58,7 @@ if [ -z ${1:-} ]; then
   done
 
   # wait for all vm's to finish
-  for i in $(seq 1 $VMs); do
+  for ((i=1; i<=VMs; i++)); do
     tail --pid=$(cat vm${i}.pid) -f /dev/null
     pid=$(cat vm${i}log.pid)
     rm -f vm${i}log.pid
@@ -72,19 +72,24 @@ fi
 export PATH="$PATH:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/sbin:/usr/local/bin"
 case "$1" in
   freebsd*)
+    TDIR="/usr/local/share/zfs"
     sudo kldstat -n zfs 2>/dev/null && sudo kldunload zfs
     sudo -E ./zfs/scripts/zfs.sh
-    TDIR="/usr/local/share/zfs"
+    sudo mv -f /var/tmp/*.txt /tmp
+    sudo newfs -U -t -L tmp /dev/vtbd1 >/dev/null
+    sudo mount -o noatime /dev/vtbd1 /var/tmp
+    sudo chmod 1777 /var/tmp
+    sudo mv -f /tmp/*.txt /var/tmp
     ;;
   *)
     # use xfs @ /var/tmp for all distros
+    TDIR="/usr/share/zfs"
+    sudo -E modprobe zfs
     sudo mv -f /var/tmp/*.txt /tmp
     sudo mkfs.xfs -fq /dev/vdb
     sudo mount -o noatime /dev/vdb /var/tmp
     sudo chmod 1777 /var/tmp
     sudo mv -f /tmp/*.txt /var/tmp
-    sudo -E modprobe zfs
-    TDIR="/usr/share/zfs"
     ;;
 esac