Do not parallelize calculus when the heaviest task is IO

Otherwise, performances get awful on HDD, and not far better on SSD.

slapos/recipe/pbs.py

@@ -194,7 +194,7 @@ class Recipe(GenericSlapRecipe, Notify, Callback):
 
         if [ -e %(backup_signature)s ]; then
           cd $BACKUP_DIR
-          find -type f ! -name backup.signature ! -wholename "./rdiff-backup-data/*" -print0 | xargs -P4 -0 sha256sum  | LC_ALL=C sort -k 66 > ../proof.signature
+          find -type f ! -name backup.signature ! -wholename "./rdiff-backup-data/*" -print0 | xargs -0 sha256sum  | LC_ALL=C sort -k 66 > ../proof.signature
           cmp backup.signature ../proof.signature || SUCCEEDED=false
           diff -ruw backup.signature ../proof.signature > ../backup.diff
           # XXX If there is a difference on the backup, we should publish the

software/kvm/template/kvm-export.sh.jinja2

@@ -25,5 +25,5 @@ $QMP_CLIENT --socket {{ socket_path }} --drive-backup $BACKUP_DIR/$BACKUP_FILE
 echo "Compressing backup..."
 {{ gzip_binary }} --force --rsyncable $BACKUP_DIR/$BACKUP_FILE
 
-cd $BACKUP_DIR && find -type f ! -name backup.signature -print0 | xargs -P4 -0 sha256sum | LC_ALL=C sort -k 66 > backup.signature
+cd $BACKUP_DIR && find -type f ! -name backup.signature -print0 | xargs -0 sha256sum | LC_ALL=C sort -k 66 > backup.signature
 

software/kvm/template/kvm-import.sh.jinja2

@@ -9,7 +9,7 @@ umask 077
 
 write_backup_proof () {
   cd {{ directory['backup'] }}
-  find -type f ! -name backup.signature ! -wholename "./rdiff-backup-data/*" -print0 | xargs -P4 -0 sha256sum  | LC_ALL=C sort -k 66 > {{ directory['srv'] }}/proof.signature
+  find -type f ! -name backup.signature ! -wholename "./rdiff-backup-data/*" -print0 | xargs -0 sha256sum  | LC_ALL=C sort -k 66 > {{ directory['srv'] }}/proof.signature
   diff -ruw {{ directory['backup'] }} {{ directory['srv'] }}/proof.signature > {{ directory['srv'] }}/backup.diff
 }
 

software/slaprunner/template/runner-export.sh.jinja2

@@ -60,7 +60,7 @@ if [ -d {{ directory['backup'] }}/runner/software ]; then
   rm {{ directory['backup'] }}/runner/software/*
 fi
 
-cd {{ directory['backup'] }} && find -type f ! -name backup.signature -print0 | xargs -P4 -0 sha256sum | LC_ALL=C sort -k 66 > backup.signature
+cd {{ directory['backup'] }} && find -type f ! -name backup.signature -print0 | xargs -0 sha256sum | LC_ALL=C sort -k 66 > backup.signature
 
 # Check that export didn't happen during backup of instances
 tmp_backup_sum=$(mktemp -p {{ directory['tmp'] }})

stack/resilient/pbsready-import.cfg.in

@@ -72,7 +72,7 @@ proof-signature-file = $${basedirectory:backup}/proof.signature
 input = inline:
   #!/${bash:location}/bin/bash
   cd $${directory:backup}
-  find -type f ! -name backup.signature ! -wholename "./rdiff-backup-data/*" -print0 | xargs -P4 -0 sha256sum  | LC_ALL=C sort -k 66 > $${:proof-signature-file}
+  find -type f ! -name backup.signature ! -wholename "./rdiff-backup-data/*" -print0 | xargs -0 sha256sum  | LC_ALL=C sort -k 66 > $${:proof-signature-file}
   diff -ruw backup.signature $${:proof-signature-file} > $${:diff-file}
 output = $${rootdirectory:bin}/post-notification-run
 mode = 0700