[pve-devel] [PATCH installer 5/6] fix #4829: tui: setup: add new ZFS `arc_max` option

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

Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
---
 proxmox-tui-installer/src/options.rs        | 55 +++++++++++++++++++--
 proxmox-tui-installer/src/setup.rs          |  2 +
 proxmox-tui-installer/src/views/bootdisk.rs |  8 ++-
 3 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/proxmox-tui-installer/src/options.rs b/proxmox-tui-installer/src/options.rs
index dab1730..cf92f1e 100644
--- a/proxmox-tui-installer/src/options.rs
+++ b/proxmox-tui-installer/src/options.rs
@@ -1,7 +1,7 @@
 use std::net::{IpAddr, Ipv4Addr};
 use std::{cmp, fmt};
 
-use crate::setup::{LocaleInfo, NetworkInfo, RuntimeInfo};
+use crate::setup::{LocaleInfo, NetworkInfo, ProxmoxProduct, RuntimeInfo};
 use crate::utils::{CidrAddress, Fqdn};
 use crate::SummaryOption;
 
@@ -190,21 +190,23 @@ pub struct ZfsBootdiskOptions {
     pub compress: ZfsCompressOption,
     pub checksum: ZfsChecksumOption,
     pub copies: usize,
+    pub arc_max: usize,
     pub disk_size: f64,
     pub selected_disks: Vec<usize>,
 }
 
 impl ZfsBootdiskOptions {
     /// This panics if the provided slice is empty.
-    pub fn defaults_from(disks: &[Disk]) -> Self {
-        let disk = &disks[0];
+    pub fn defaults_from(runinfo: &RuntimeInfo) -> Self {
+        let disk = &runinfo.disks[0];
         Self {
             ashift: 12,
             compress: ZfsCompressOption::default(),
             checksum: ZfsChecksumOption::default(),
             copies: 1,
+            arc_max: default_zfs_arc_max(crate::current_product(), runinfo.total_memory),
             disk_size: disk.size,
-            selected_disks: (0..disks.len()).collect(),
+            selected_disks: (0..runinfo.disks.len()).collect(),
         }
     }
 }
@@ -441,3 +443,48 @@ impl InstallerOptions {
         ]
     }
 }
+
+/// Calculates the default upper limit for the ZFS ARC size.
+/// See also <https://bugzilla.proxmox.com/show_bug.cgi?id=4829> and
+/// https://openzfs.github.io/openzfs-docs/Performance%20and%20Tuning/Module%20Parameters.html#zfs-arc-max
+///
+/// # Arguments
+/// * `product` - The product to be installed
+/// * `total_memory` - Total memory installed in the system, in MiB
+fn default_zfs_arc_max(product: ProxmoxProduct, total_memory: usize) -> usize {
+    if product != ProxmoxProduct::PVE {
+        // Use ZFS default for non-PVE
+        0
+    } else {
+        ((total_memory as f64) / 10.)
+            .round()
+            .clamp(64., 16. * 1024.) as usize
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn zfs_arc_limit() {
+        const TESTS: &[(usize, usize)] = &[
+            (16, 64), // at least 64 MiB
+            (1024, 102),
+            (4 * 1024, 410),
+            (8 * 1024, 819),
+            (150 * 1024, 15360),
+            (160 * 1024, 16384),
+            (1024 * 1024, 16384), // maximum of 16 GiB
+        ];
+
+        for (total_memory, expected) in TESTS {
+            assert_eq!(
+                default_zfs_arc_max(ProxmoxProduct::PVE, *total_memory),
+                *expected
+            );
+            assert_eq!(default_zfs_arc_max(ProxmoxProduct::PBS, *total_memory), 0);
+            assert_eq!(default_zfs_arc_max(ProxmoxProduct::PMG, *total_memory), 0);
+        }
+    }
+}
diff --git a/proxmox-tui-installer/src/setup.rs b/proxmox-tui-installer/src/setup.rs
index e51bb4d..3f41db4 100644
--- a/proxmox-tui-installer/src/setup.rs
+++ b/proxmox-tui-installer/src/setup.rs
@@ -114,6 +114,7 @@ struct InstallZfsOption {
     #[serde(serialize_with = "serialize_as_display")]
     checksum: ZfsChecksumOption,
     copies: usize,
+    arc_max: usize,
 }
 
 impl From<ZfsBootdiskOptions> for InstallZfsOption {
@@ -123,6 +124,7 @@ impl From<ZfsBootdiskOptions> for InstallZfsOption {
             compress: opts.compress,
             checksum: opts.checksum,
             copies: opts.copies,
+            arc_max: opts.arc_max,
         }
     }
 }
diff --git a/proxmox-tui-installer/src/views/bootdisk.rs b/proxmox-tui-installer/src/views/bootdisk.rs
index a018e71..5ea0cee 100644
--- a/proxmox-tui-installer/src/views/bootdisk.rs
+++ b/proxmox-tui-installer/src/views/bootdisk.rs
@@ -131,6 +131,11 @@ impl AdvancedBootdiskOptionsView {
     }
 
     fn fstype_on_submit(siv: &mut Cursive, disks: &[Disk], fstype: &FsType) {
+        let runinfo = siv
+            .user_data::<InstallerState>()
+            .map(|state| state.runtime_info.clone())
+            .unwrap();
+
         siv.call_on_name("advanced-bootdisk-options-dialog", |view: &mut Dialog| {
             if let Some(AdvancedBootdiskOptionsView { view }) =
                 view.get_content_mut().downcast_mut()
@@ -142,7 +147,7 @@ impl AdvancedBootdiskOptionsView {
                     )),
                     FsType::Zfs(_) => view.add_child(ZfsBootdiskOptionsView::new(
                         disks,
-                        &ZfsBootdiskOptions::defaults_from(disks),
+                        &ZfsBootdiskOptions::defaults_from(&runinfo),
                     )),
                     FsType::Btrfs(_) => view.add_child(BtrfsBootdiskOptionsView::new(
                         disks,
@@ -534,6 +539,7 @@ impl ZfsBootdiskOptionsView {
                 compress,
                 checksum,
                 copies,
+                arc_max: 0, // use built-in ZFS default value
                 disk_size,
                 selected_disks,
             },
-- 
2.41.0