From 8b4c648fa71e286964d9161fb99867f67192c721 Mon Sep 17 00:00:00 2001
From: The 8472 <git@infinite-source.de>
Date: Sat, 25 Oct 2025 02:26:32 +0200
Subject: [PATCH 1/3] optimize ext4 mount options that can be toggled at
 runtime.

---
 .github/workflows/ci.yml      |  3 +++
 src/ci/scripts/tune-rootfs.sh | 25 +++++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100755 src/ci/scripts/tune-rootfs.sh

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d440b296d2753..6f5867aad90dc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -117,6 +117,9 @@ jobs:
         with:
           fetch-depth: 2
 
+      - name: remount root filesystem
+        run: src/ci/scripts/tune-rootfs.sh
+
       # Free up disk space on Linux by removing preinstalled components that
       # we do not need. We do this to enable some of the less resource
       # intensive jobs to run on free runners, which however also have
diff --git a/src/ci/scripts/tune-rootfs.sh b/src/ci/scripts/tune-rootfs.sh
new file mode 100755
index 0000000000000..6ac8d96c27dcc
--- /dev/null
+++ b/src/ci/scripts/tune-rootfs.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+
+set -euo pipefail
+IFS=$'\n\t'
+
+source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
+
+if isLinux && [[ $(findmnt -n /) =~ "ext4" ]] ; then
+    # noauto_da_alloc since auto_da_alloc causes sync IO for some common file creation patterns
+    # lazytime avoids sync IO when (rel)atime updates are applied
+    # barrier=0 disables write cache flushing, which can reduce latency at the cost of durability,
+    #    but CI machines are ephemeral, so we don't need to be crash-proof.
+    #
+    # Ideally we'd set additional options, but those would require
+    # a reboot or unmounting the rootfs.
+    sudo mount -oremount,delalloc,lazytime,barrier=0,noauto_da_alloc /
+    sudo bash -c 'echo "write through" > /sys/block/sda/queue/write_cache' || true
+    sudo bash -c 'echo "write through" > /sys/block/sdb/queue/write_cache' || true
+
+    ionice -c 3 fstrim / &
+
+    lsblk
+
+    mount
+fi

From 7b2545a169aee457d77a8824653f2e590ace4372 Mon Sep 17 00:00:00 2001
From: The 8472 <git@infinite-source.de>
Date: Sun, 26 Oct 2025 12:25:48 +0100
Subject: [PATCH 2/3] run iostat while freeing up disk space

---
 src/ci/scripts/free-disk-space-linux.sh | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/ci/scripts/free-disk-space-linux.sh b/src/ci/scripts/free-disk-space-linux.sh
index ac3c9cfb28b87..2f4e93ba8b82f 100755
--- a/src/ci/scripts/free-disk-space-linux.sh
+++ b/src/ci/scripts/free-disk-space-linux.sh
@@ -253,11 +253,16 @@ AVAILABLE_INITIAL=$(getAvailableSpace)
 
 printDF "BEFORE CLEAN-UP:"
 echo ""
+
+iostat -x 20 &
+
 execAndMeasureSpaceChange cleanPackages "Unused packages"
 execAndMeasureSpaceChange cleanDocker "Docker images"
 execAndMeasureSpaceChange cleanSwap "Swap storage"
 execAndMeasureSpaceChange removeUnusedFilesAndDirs "Unused files and directories"
 
+kill %1
+
 # Output saved space statistic
 echo ""
 printDF "AFTER CLEAN-UP:"

From 964c658eb188912dcfd19421d950bd1f2ee6cbdb Mon Sep 17 00:00:00 2001
From: The 8472 <git@infinite-source.de>
Date: Sun, 26 Oct 2025 13:36:59 +0100
Subject: [PATCH 3/3] parallel delete

---
 src/ci/scripts/free-disk-space-linux.sh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/ci/scripts/free-disk-space-linux.sh b/src/ci/scripts/free-disk-space-linux.sh
index 2f4e93ba8b82f..b20d19cbb5f58 100755
--- a/src/ci/scripts/free-disk-space-linux.sh
+++ b/src/ci/scripts/free-disk-space-linux.sh
@@ -173,8 +173,11 @@ removeUnusedFilesAndDirs() {
         fi
     done
 
-    # Remove all files and directories at once to save time.
-    sudo rm -rf "${to_remove[@]}"
+    # GHA has high read latencies for uncached data
+    # so we traverse directories in parallel and feed the output to rm
+    printf '%s\n' "${to_remove[@]}" | \
+        (xargs -P 6 -I{} -- find {} -type f -printf '%p\n\c' || true) | \
+        sudo xargs -r -P 8 -n 100 -- rm -rf
 }
 
 execAndMeasureSpaceChange() {