Recent changes in the linux kernel caused NFS readahead to default to 128 from the previous default of 15 * rsize. This causes performance penalties to some read-heavy workloads, which can be fixed by tuning the readahead for that given mount. Specifically, the read troughput on a sec=krb5p mount drops by 50-75% when comparing the default readahead with a readahead of 15360. Previous discussions: https://lore.kernel.org/linux-nfs/20210803130717.2890565-1-trbecker@xxxxxxxxx/ I attempted to add a non-kernel option to mount.nfs, and it was rejected. https://lore.kernel.org/linux-nfs/20210811171402.947156-1-trbecker@xxxxxxxxx/ Attempted to add a mount option to the kernel, rejected as well. I had started a separate tool to set the readahead of BDIs, but the scope is specifically for NFS, so I would like to get the community feeling for having this in nfs-utils. This patch series introduces nfs-readahead-udev, a utility to automatically set NFS readahead when NFS is mounted. The utility is triggered by udev when a new BDI is added, returns to udev the value of the readahead that should be used. The tool currently supports setting read ahead per mountpoint, nfs major version, or by a global default value. Thiago Becker (7): Create nfs-readahead-udev readahead: configure udev readahead: create logging facility readahead: only set readahead for nfs devices. readahead: create the configuration file readahead: add mountpoint and fstype options readahead: documentation .gitignore | 6 + configure.ac | 4 + tools/Makefile.am | 2 +- tools/nfs-readahead-udev/99-nfs_bdi.rules.in | 1 + tools/nfs-readahead-udev/Makefile.am | 26 +++ tools/nfs-readahead-udev/config_parser.c | 25 +++ tools/nfs-readahead-udev/config_parser.h | 14 ++ tools/nfs-readahead-udev/list.h | 48 ++++ tools/nfs-readahead-udev/log.h | 16 ++ tools/nfs-readahead-udev/main.c | 211 ++++++++++++++++++ .../nfs-readahead-udev/nfs-readahead-udev.man | 47 ++++ tools/nfs-readahead-udev/parser.y | 85 +++++++ tools/nfs-readahead-udev/readahead.conf | 15 ++ tools/nfs-readahead-udev/scanner.l | 19 ++ tools/nfs-readahead-udev/syslog.c | 47 ++++ 15 files changed, 565 insertions(+), 1 deletion(-) create mode 100644 tools/nfs-readahead-udev/99-nfs_bdi.rules.in create mode 100644 tools/nfs-readahead-udev/Makefile.am create mode 100644 tools/nfs-readahead-udev/config_parser.c create mode 100644 tools/nfs-readahead-udev/config_parser.h create mode 100644 tools/nfs-readahead-udev/list.h create mode 100644 tools/nfs-readahead-udev/log.h create mode 100644 tools/nfs-readahead-udev/main.c create mode 100644 tools/nfs-readahead-udev/nfs-readahead-udev.man create mode 100644 tools/nfs-readahead-udev/parser.y create mode 100644 tools/nfs-readahead-udev/readahead.conf create mode 100644 tools/nfs-readahead-udev/scanner.l create mode 100644 tools/nfs-readahead-udev/syslog.c -- 2.35.1
