DragonFly commits List (threaded) for 2012-12
git: kernel - Change allocvnode() to not recursively block freeing vnodes
Author: Matthew Dillon <firstname.lastname@example.org>
Date: Fri Dec 7 18:52:30 2012 -0800
kernel - Change allocvnode() to not recursively block freeing vnodes
allocvnode() has caused many deadlock issues over the years, including
recent issues with softupdates, because it is often called from deep
within VFS modules and attempts to clean and free unrelated vnodes when
the vnode limit is reached to make room for the new one.
* numvnodes is not protected by any locks and needs atomic ops.
* Change allocvnode() to always allocate and not attempt to free
* allocvnode() now flags the LWP to handle reducing the number of vnodes
in the system as of when it returns to userland instead. Consolidate
several flags into a single conditional function call, lwpuserret().
When triggered, this code will do a limited scan of the free list to
try to find vnodes to free.
* The vnlru_proc_wait() code existed to handle a separate algorithm
related to vnodes with cached buffers and VM pages but represented
a major bottleneck in the system.
Remove vnlru_proc_wait() and allow vnodes with buffers and/or non-empty
VM objects to be placed on the free list.
This also requires not vhold()ing the vnode for related buffer cache
buffer since the vnode will not go away until related buffers have been
cleaned out. We shouldn't need those holds.
Summary of changes:
sys/kern/kern_proc.c | 21 ++++++
sys/kern/vfs_lock.c | 128 ++++++++++++++++++++++------------
sys/kern/vfs_mount.c | 24 +++----
sys/kern/vfs_subr.c | 4 +-
sys/platform/pc32/i386/trap.c | 10 +--
sys/platform/pc64/x86_64/trap.c | 10 +--
sys/platform/vkernel/i386/trap.c | 10 +--
sys/platform/vkernel64/x86_64/trap.c | 10 +--
sys/sys/proc.h | 6 ++-
sys/sys/vnode.h | 4 +-
10 files changed, 138 insertions(+), 89 deletions(-)
DragonFly BSD source repository