much higher filesystem I/O performance, and much better paging performance. It
represents the culmination of over 6 months of R&D.
The majority of the merged VM/cache work is by John Dyson.
The following highlights the most significant changes. Additionally, there are
(mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to
support the new VM/buffer scheme.
vfs_bio.c:
Significant rewrite of most of vfs_bio to support the merged VM buffer cache
scheme. The scheme is almost fully compatible with the old filesystem
interface. Significant improvement in the number of opportunities for write
clustering.
vfs_cluster.c, vfs_subr.c
Upgrade and performance enhancements in vfs layer code to support merged
VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff.
vm_object.c:
Yet more improvements in the collapse code. Elimination of some windows that
can cause list corruption.
vm_pageout.c:
Fixed it, it really works better now. Somehow in 2.0, some "enhancements"
broke the code. This code has been reworked from the ground-up.
vm_fault.c, vm_page.c, pmap.c, vm_object.c
Support for small-block filesystems with merged VM/buffer cache scheme.
pmap.c vm_map.c
Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of
kernel PTs.
vm_glue.c
Much simpler and more effective swapping code. No more gratuitous swapping.
proc.h
Fixed the problem that the p_lock flag was not being cleared on a fork.
swap_pager.c, vnode_pager.c
Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the
code doesn't need it anymore.
machdep.c
Changes to better support the parameter values for the merged VM/buffer cache
scheme.
machdep.c, kern_exec.c, vm_glue.c
Implemented a seperate submap for temporary exec string space and another one
to contain process upages. This eliminates all map fragmentation problems
that previously existed.
ffs_inode.c, ufs_inode.c, ufs_readwrite.c
Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on
busy buffers.
Submitted by: John Dyson and David Greenman
of attributes so that `cp -p' to an msdos file system can succeed under
favourable circumstances (no uid or gid changes and no nonzero flags
except SF_ARCHIVED).
msdosfs_vnops.c:
The in-core inode flags were confused with the on-disk inode flags, so
chflags() clobbered the lock flag and caused a panic.
denode.h, msdosfs_denode.c, msdosfs_vnops.c:
Support the msdosfs archive attibute (ATTR_ARCHIVE) by mapping it to
the complement of the SF_ARCHIVED flag and setting the ATTR_ARCHIVE
bit when a file's modification time is set (but not when a file's
permissions are set; this is the standard wrong DOS behaviour).
denode.h, msdosfs_denode.c:
Remove the DE_UPDAT() macro. It was only used once, and the corresponding
macro in ufs has already been removed.
denode.h:
Don't change the timestamp for directories in DE_TIMES() (be consistent
with deupdat()).
msdosfs_vnops.c:
Handle chown() better: return EPERM instead of EINVAL if there are
insufficient permissions; otherwise, allow null changes.
DE_UPDATE was confused with DE_MODIFIED in some places (they do have
confusing names). Handle them exactly the same as IN_UPDATE and
IN_MODIFIED. This fixes chmod() and chown() clobbering the mtime
and other bugs.
DE_MODIFIED was set but not used.
Parenthesize macro args.
DE_TIMES() now takes a timeval arg instead of a timespec arg. It was
stupid to use a macro for speed and do unused conversions to prepare
for the macro.
Restore the left shifting of the DOS seconds count by 1. It got
lost among the shifts for the bitfields, so DOS seconds counts
appeared to range from 0 to 29 seconds (step 1) instead of 0 to 58
seconds (step 2).
Actually use the passed-in mtime in deupdat() as documented so that
utimes() works.
Change `extern __inline's to `static inline's so that msdosfs_fat.o
can be linked when it is compiled without -O.
Remove faking of directory mtimes to always be the current time. It's
more surprising for directory mtimes to change when you read the
directories than for them not to change when you write the directories.
This should be controlled by a mount-time option if at all.
I'm not sure if this is just masking another problem (like, should
ap->a_eofflag EVER be NULL?), but if it prevents a panic for now then
it may save an ALPHA customer.
Submitted by: jhay
