[pbs-devel] [PATCH] Set MMAP_THRESHOLD to a fixed value (128K)

[Dietmar Maurer <dietmar@proxmox.com>]

This reduces RSS size by factor 10-20 when running backups.

Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
---
 pbs-tools/src/lib.rs              | 17 +++++++++++++++++
 proxmox-backup-client/src/main.rs |  2 ++
 src/bin/proxmox-backup-api.rs     |  2 ++
 src/bin/proxmox-backup-proxy.rs   |  3 +++
 4 files changed, 24 insertions(+)

diff --git a/pbs-tools/src/lib.rs b/pbs-tools/src/lib.rs
index 053b3c0c..cd8bb546 100644
--- a/pbs-tools/src/lib.rs
+++ b/pbs-tools/src/lib.rs
@@ -8,3 +8,20 @@ pub mod sha;
 pub mod ticket;
 
 pub mod async_lru_cache;
+
+
+#[link(name = "c")]
+extern "C" {
+    fn mallopt(para: isize, val: isize);
+}
+
+/// Set MMAP_THRESHOLD to a fixed value (128K)
+///
+/// This reduces RSS size by factor 10-20 when running backups (not
+/// sure why).
+pub fn setup_libc_malloc_opts() {
+    unsafe {
+        const M_MMAP_THRESHOLD: isize = -3; // from malloc.h
+        mallopt(M_MMAP_THRESHOLD, 4096*32);
+    }
+}
diff --git a/proxmox-backup-client/src/main.rs b/proxmox-backup-client/src/main.rs
index 50682637..a51d5bef 100644
--- a/proxmox-backup-client/src/main.rs
+++ b/proxmox-backup-client/src/main.rs
@@ -1465,6 +1465,8 @@ impl ReadAt for BufferedDynamicReadAt {
 
 fn main() {
 
+    pbs_tools::setup_libc_malloc_opts();
+
     let backup_cmd_def = CliCommand::new(&API_METHOD_CREATE_BACKUP)
         .arg_param(&["backupspec"])
         .completion_cb("repository", complete_repository)
diff --git a/src/bin/proxmox-backup-api.rs b/src/bin/proxmox-backup-api.rs
index e6fc5f23..ee037a3b 100644
--- a/src/bin/proxmox-backup-api.rs
+++ b/src/bin/proxmox-backup-api.rs
@@ -19,6 +19,8 @@ use proxmox_backup::auth_helpers::*;
 use proxmox_backup::config;
 
 fn main() {
+    pbs_tools::setup_libc_malloc_opts();
+
     proxmox_backup::tools::setup_safe_path_env();
 
     if let Err(err) = proxmox_async::runtime::main(run()) {
diff --git a/src/bin/proxmox-backup-proxy.rs b/src/bin/proxmox-backup-proxy.rs
index 523966cf..13025271 100644
--- a/src/bin/proxmox-backup-proxy.rs
+++ b/src/bin/proxmox-backup-proxy.rs
@@ -73,6 +73,9 @@ use proxmox_backup::server::do_verification_job;
 use proxmox_backup::server::do_prune_job;
 
 fn main() -> Result<(), Error> {
+
+    pbs_tools::setup_libc_malloc_opts();
+
     proxmox_backup::tools::setup_safe_path_env();
 
     let backup_uid = pbs_config::backup_user()?.uid;
-- 
2.30.2