Disable swap in Go build

We have migrated to Go 1.7+ and as such we no longer need to be enabling
swap space for our builds.

Signed-off-by: Steve Kuznetsov <skuznets@redhat.com>

hack/common.sh

@@ -210,11 +210,6 @@ os::build::internal::build_binaries() {
       fi
     done
 
-    # Temporarily enable swap for the duration of the build until we move
-    # to Go 1.7
-    os::build::enable_swap
-    trap "os::build::disable_swap" EXIT
-
     local host_platform=$(os::build::host_platform)
     local platform
     for platform in "${platforms[@]+"${platforms[@]}"}"; do
@@ -785,87 +780,6 @@ function os::build::image() {
 }
 readonly -f os::build::image
 
-# os::build::enable_swap attempts to enable swap for the system if a) this is Linux and b)
-# the amount of physical memory is less than 10GB. This is a stopgap until we have
-# better control over memory use in Go 1.7+.
-function os::build::enable_swap() {
-  # if we aren't on linux or have more than 9GB of memory
-  if [[ -n "${OS_BUILD_SWAP_DISABLE-}" || "$(go env GOHOSTOS)" != "linux" || "$( os::build::physmem_gb )" -gt 9 ]]; then
-    return
-  fi
-  # if we don't have the swapon command available
-  if ! swapon &>/dev/null; then
-    return
-  fi
-  # if swap is already on
-  if [[ "$( swapon --show --noheadings | wc -l )" -ne 0 ]]; then
-    return
-  fi
-  echo "++ temporarily enabling swap space to assist in building in limited memory - use OS_BUILD_SWAP_DISABLE=1 to bypass"
-
-  (
-    set -e
-    sudo cp /etc/fstab /origin-backupfstab
-    sudo dd if=/dev/zero of=/origin-swapfile bs=1M count=${OS_BUILD_SWAP_SIZE:-2048}
-    sudo chmod 600 /origin-swapfile
-    sudo mkswap /origin-swapfile
-    sudo swapon /origin-swapfile
-    sudo /bin/sh -c 'echo "/origin-swapfile none swap defaults 0 0" >> /etc/fstab'
-  ) &>/dev/null || true
-}
-readonly -f os::build::enable_swap
-
-# os::build::disable_swap undoes the effects of os::build::enable_swap
-function os::build::disable_swap() {
-  # if we aren't on linux or have more than 9GB of memory
-  if [[ -n "${OS_BUILD_SWAP_DISABLE-}" || "$(go env GOHOSTOS)" != "linux" ]]; then
-    return
-  fi
-  # if we previously set up a swapfile
-  if [[ ! -f /origin-swapfile ]]; then
-    return
-  fi
-  (
-    set +e
-    sudo swapoff /origin-swapfile
-    sudo cp /origin-backupfstab /etc/fstab
-    sudo rm -f /origin-backupfstab /origin-swapfile
-  ) || true
-}
-readonly -f os::build::disable_swap
-
-# os::build::physmem_gb returns the approximate gigabytes of memory on the system
-# This is copied verbatim from kube for the purposes of detecting how much available
-# memory we have for building.
-function os::build::physmem_gb() {
-  local mem
-
-  # Linux kernel version >=3.14, in kb
-  if mem=$(grep MemAvailable /proc/meminfo | awk '{ print $2 }'); then
-    echo $(( ${mem} / 1048576 ))
-    return
-  fi
-
-  # Linux, in kb
-  if mem=$(grep MemTotal /proc/meminfo | awk '{ print $2 }'); then
-    echo $(( ${mem} / 1048576 ))
-    return
-  fi
-
-  # OS X, in bytes. Note that get_physmem, as used, should only ever
-  # run in a Linux container (because it's only used in the multiple
-  # platform case, which is a Dockerized build), but this is provided
-  # for completeness.
-  if mem=$(sysctl -n hw.memsize 2>/dev/null); then
-    echo $(( ${mem} / 1073741824 ))
-    return
-  fi
-
-  # If we can't infer it, just give up and assume a low memory system
-  echo 1
-}
-readonly -f os::build::physmem_gb
-
 # os::build::require_clean_tree exits if the current Git tree is not clean.
 function os::build::require_clean_tree() {
   if ! git diff-index --quiet HEAD -- || test $(git ls-files --exclude-standard --others | wc -l) != 0; then