[pve-devel] [PATCH installer v2 3/3] proxinstall: expose arc size setting for zfs bootdisks for all products

[Christoph Heiss <c.heiss@proxmox.com>]

For non-PVE products, simply use the ZFS defaults (aka. 50%) and leave
unset, if the user never touches that setting.

Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
---
Changes v1 -> v2:
  * add some more explanatory comments
  * shuffle around code to support placeholder-like value

 Proxmox/Install/RunEnv.pm |  3 ++-
 proxinstall               | 37 +++++++++++++++++++++++++------------
 2 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/Proxmox/Install/RunEnv.pm b/Proxmox/Install/RunEnv.pm
index c393f67..2eb26f4 100644
--- a/Proxmox/Install/RunEnv.pm
+++ b/Proxmox/Install/RunEnv.pm
@@ -316,7 +316,8 @@ our $ZFS_ARC_SYSMEM_PERCENTAGE = 0.1; # use 10% of available system memory by de
 # Calculates the default upper limit for the ZFS ARC size.
 # Returns the default ZFS maximum ARC size in MiB.
 sub default_zfs_arc_max {
-    # Use ZFS default on non-PVE
+    # For products other the PVE, just let ZFS decide on its own. Setting `0`
+    # causes the installer to skip writing the `zfs_arc_max` module parameter.
     return 0 if Proxmox::Install::ISOEnv::get('product') ne 'pve';

     my $default_mib = get('total_memory') * $ZFS_ARC_SYSMEM_PERCENTAGE;
diff --git a/proxinstall b/proxinstall
index 81dd368..ab89a08 100755
--- a/proxinstall
+++ b/proxinstall
@@ -1167,21 +1167,34 @@ my $create_raid_advanced_grid = sub {
     $spinbutton_copies->set_value($copies);
     push @$labeled_widgets, ['copies', $spinbutton_copies];

-    if ($iso_env->{product} eq 'pve') {
-	my $total_memory = Proxmox::Install::RunEnv::get('total_memory');
-
-	my $spinbutton_arc_max = Gtk3::SpinButton->new_with_range(
-	    $Proxmox::Install::RunEnv::ZFS_ARC_MIN_SIZE_MIB, $total_memory, 1);
-	$spinbutton_arc_max->set_tooltip_text('Maximum ARC size in megabytes');
-	$spinbutton_arc_max->signal_connect('value-changed' => sub {
-	    my $w = shift;
-	    Proxmox::Install::Config::set_zfs_opt('arc_max', $w->get_value_as_int());
-	});
-	my $arc_max = Proxmox::Install::Config::get_zfs_opt('arc_max');
+    my $total_memory = Proxmox::Install::RunEnv::get('total_memory');
+
+    my $spinbutton_arc_max = Gtk3::SpinButton->new_with_range(
+	$Proxmox::Install::RunEnv::ZFS_ARC_MIN_SIZE_MIB, $total_memory, 1);
+    $spinbutton_arc_max->set_tooltip_text('Maximum ARC size in megabytes');
+    my $arc_max = Proxmox::Install::Config::get_zfs_opt('arc_max');
+
+    # GTKs SpinButton does not support a placeholder value, unfortunaly. That means we also
+    # have to set the value normally for non-PVE products, where the ZFS default should be used,
+    # in case the user does not explicitly set a value.
+    # But due to the signal-based nature of GTK, as long as the user never touches the spinbutton,
+    # `Proxmox::Install::Config::set_zfs_opt('arc_max', ..)` never gets called, thus the default
+    # value (which is 0 for non-PVE) won't get overwritten and no modprobe file is written.
+    if ($arc_max > 0) {
 	$spinbutton_arc_max->set_value($arc_max);
-	push @$labeled_widgets, ['ARC max size', $spinbutton_arc_max, 'MiB'];
+    } else {
+	# .. but we need to display the "real" value to the user
+	$spinbutton_arc_max->set_value($total_memory * 0.5);
     }

+    # We need to connect the signal afterwards, to avoid triggering it using ->set_value() above.
+    $spinbutton_arc_max->signal_connect('value-changed' => sub {
+	my $w = shift;
+	Proxmox::Install::Config::set_zfs_opt('arc_max', $w->get_value_as_int());
+    });
+
+    push @$labeled_widgets, ['ARC max size', $spinbutton_arc_max, 'MiB'];
+
     push @$labeled_widgets, ['hdsize', $hdsize_btn, 'GB'];
     return $create_label_widget_grid->($labeled_widgets);;
 };
--
2.43.0