From 6a075baa477e12979bf312b140bee38694b2971a Mon Sep 17 00:00:00 2001
From: tilpner
Date: Wed, 5 Sep 2018 11:18:53 +0200
Subject: Don't always use lz4, might be slower on fast disks

---
 default.nix | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/default.nix b/default.nix
index 3966c2c..790bd36 100644
--- a/default.nix
+++ b/default.nix
@@ -377,6 +377,17 @@ in rec {
 
   qemuDriveOptions = lib.concatMapStringsSep " " (d: "-drive if=virtio,readonly,format=raw,file=${d}");
 
+  suspensionUseCompression = true;
+  suspensionWriteCommand =
+    if suspensionUseCompression
+    then "${lz4}/bin/lz4 -9 --favor-decSpeed -"
+    else "cat >";
+
+  suspensionReadCommand =
+    if suspensionUseCompression
+    then "${lz4}/bin/lz4 -d --favor-decSpeed"
+    else "cat ";
+
   run = args@{ name, fullPath, initrdPath, storeDrives, mem, desc, ... }: writeShellScriptBin "run-qemu" ''
     # ${name}
     # needs ''${concatStringsSep ", " fullPath}
@@ -396,7 +407,7 @@ in rec {
       ${qemu}/bin/qemu-system-x86_64 \
       ${commonQemuOptions}
       ${qemuDriveOptions (builtins.attrValues storeDrives)} \
-        -incoming 'exec:${lz4}/bin/lz4 -d ${suspension args}' | ${dos2unix}/bin/dos2unix -f | head -c 1M
+        -incoming 'exec:${suspensionReadCommand} ${suspension args}' | ${dos2unix}/bin/dos2unix -f | head -c 1M
 
     # ^ qemu incorrectly does crlf conversion, check in the future if still necessary
   '' // args;
@@ -416,7 +427,7 @@ in rec {
 
       ( read ready < job/control
         echo '{ "execute": "qmp_capabilities" }'
-        echo '{ "execute": "migrate", "arguments": { "uri": "exec:lz4 -9 - '$out'" } }'
+        echo '{ "execute": "migrate", "arguments": { "uri": "exec:${suspensionWriteCommand} '$out'" } }'
         sleep 15 # FIXME
         echo '{ "execute": "quit" }'
       ) | ${netcat}/bin/nc -lU job/qmp &
-- 
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