Source: coreutils Severity: normal Tags: patch X-Debbugs-Cc: [email protected]
Dear Maintainers, I am forwarding Ubuntu bug report[1] about slow Lustre filesystem performance: --- Users running Lustre filesystems on Ubuntu experience severe performance degradation with 'du' on large directories (10K+ files). Operations that should take seconds can take minutes. The issue occurs because by default, coreutils sorts directory entries by increasing inode number for large directories. This breaks Lustre's "statahead" prefetching feature, which activates when it detects sequential file access patterns and prefetches metadata accordingly. When coreutils sorts entries by inode (which are scattered), Lustre sees random access and doesn't activate statahead at all, forcing every file access to be an individual network round-trip to the server instead of being served from prefetched cache. Testing the du command after applying the patch to coreutils demonstrates ~5x performance improvement, with ~9x improvement reported in production environments. This primarily affects HPC and research environments, where Lustre is commonly deployed. The fix adds Lustre's filesystem magic number (0x0BD00BD0) to the list of filesystems where inode sorting should be skipped, matching existing behavior for NFS, CIFS, and tmpfs. The change is minimal, has been accepted upstream in coreutils, and only affects Lustre filesystems - all other filesystems remain unchanged. --- The issue can be fixed either by applying the upstream patch[2], or upgrading coreutils to 9.10. [1] https://bugs.launchpad.net/ubuntu/+source/gnulib/+bug/2137373 [2] https://github.com/coreutils/gnulib/commit/578b8d7dc5e3fc00d308660fa60bb529a2e42bb3 -- System Information: Debian Release: trixie/sid APT prefers noble-updates APT policy: (500, 'noble-updates'), (500, 'noble-security'), (500, 'noble'), (100, 'noble-backports') Architecture: amd64 (x86_64) Kernel: Linux 6.17.0-1011-oem (SMP w/24 CPU threads; PREEMPT) Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled -- no debconf information
