freebsd kernel with SKQ
d9e9650a36
it. There are two problems which shall be addressed for shared lookups use to have measurable effect on nullfs scalability: 1. When vfs_lookup() calls VOP_LOOKUP() for nullfs, which passes lookup operation to lower fs, resulting vnode is often only shared-locked. Then null_nodeget() cannot instantiate covering vnode for lower vnode, since insmntque1() and null_hashins() require exclusive lock on the lower. Change the assert that lower vnode is exclusively locked to only require any lock. If null hash failed to find pre-existing nullfs vnode for lower vnode and the vnode is shared-locked, the lower vnode lock is upgraded. 2. Nullfs reclaims its vnodes on deactivation. This is due to nullfs inability to detect reclamation of the lower vnode. Reclamation of a nullfs vnode at deactivation time prevents a reference to the lower vnode to become stale. Change nullfs VOP_INACTIVE to not reclaim the vnode, instead use the VFS_RECLAIM_LOWERVP to get notification and reclaim upper vnode together with the reclamation of the lower vnode. Note that nullfs reclamation procedure calls vput() on the lowervp vnode, temporary unlocking the vnode being reclaimed. This seems to be fine for MPSAFE filesystems, but not-MPSAFE code often put partially initialized vnode on some globally visible list, and later can decide that half-constructed vnode is not needed. If nullfs mount is created above such filesystem, then other threads might catch such not properly initialized vnode. Instead of trying to overcome this case, e.g. by recursing the lower vnode lock in null_reclaim_lowervp(), I decided to rely on nearby removal of the support for non-MPSAFE filesystems. In collaboration with: pho MFC after: 3 weeks |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html