existing mechanism uses a global queue for some buffers and the
vp->b_dirtyblkhd queue for others. This turns sequential writes into
randomly ordered writes to the server, affecting both read and write
performance. The existing mechanism also copes badly with hung
servers, tending to block accesses to other servers when all the iods
are waiting for a hung server.
The new mechanism uses a queue for each mount point. All asynchronous
i/o goes through this queue which preserves the ordering of requests.
A simple mechanism ensures that the iods are shared out fairly between
active mount points. This removes the sysctl variable vfs.nfs.dwrite
since the new queueing mechanism removes the old delayed write code
completely.
This should go into the 2.2 branch.
contents are discarded, including the cached seek cookies.
Unfortunately, if the directory was larger than NFS_DIRBLKSIZ, then
this confused nfs_readdirrpc(), making it appear as if the directory
was truncated.
Reviewed by: Karl Denninger <karl@Mcs.Net>
/*
* Structure defined by POSIX.4 to be like a timeval.
*/
struct timespec {
time_t ts_sec; /* seconds */
long ts_nsec; /* and nanoseconds */
};
The correct names of the fields are tv_sec and tv_nsec.
Reminded by: James Drobina <jdrobina@infinet.com>
rick@snowhite.cis.uoguelph.ca:
1. Clear B_NEEDCOMMIT in nfs_write to make sure that dirty data is
correctly send to the server. If a buffer was dirtied when it was in
the B_DELWRI+B_NEEDCOMMIT state, the state of the buffer was left
unchanged and when the buffer was later cleaned, just a commit rpc was
made to the server to complete the previous write. Clearing
B_NEEDCOMMIT ensures that another write is made to the server.
2. If a server returned a server (for whatever reason) returned an
answer to a write RPC that implied that fewer bytes than requested
were written, bad things would happen.
3. The setattr operation passed on the atime in stead of the mtime to
the server. The fix is trivial.
4. XIDs always started at 0, but this caused some servers (older DEC
OSF/1 3.0 so I've been told) who had very long-lasting XID caches to
get confused if, after a reboot of a BSD client, RPCs came in with a
XID that had in the past been used before from that client. Patch is
to use the current time in seconds as a starting point for XIDs. The
patch below is not perfect, because it requires the root fs to be
mounted first. This is because of the check BSD systems do, comparing
FS time to system time.
Reviewed by: Bruce Evans, Terry Lambert.
Obtained from: frank@fwi.uva.nl (Frank van der Linden) via rick@snowhite.cis.uoguelph.ca
it 1138 times (:-() in casts and a few more times in declarations.
This change is null for the i386.
The type has to be `typedef int vop_t(void *)' and not `typedef
int vop_t()' because `gcc -Wstrict-prototypes' warns about the
latter. Since vnode op functions are called with args of different
(struct pointer) types, neither of these function types is any use
for type checking of the arg, so it would be preferable not to use
the complete function type, especially since using the complete
type requires adding 1138 casts to avoid compiler warnings and
another 40+ casts to reverse the function pointer conversions before
calling the functions.
These functions went away:
enosys (hasn't been used for some time)
enxio
enodev
enoioctl (was used only once, actually for a vop)
if_tun.c:
Continued cleaning up...
conf.h:
Probably fixed the type of d_reset_t. It is hard to tell the correct
type because there are no non-dummy device reset functions.
Removed last vestige of ambiguous sleep message strings.
filesystem layer, as was done in lite-2. Merged in some other cosmetic
changes while I was at it. Rewrote most of msdosfs_access() to be more
like ufs_access() and to include the FS read-only check.
Obtained from: partially from 4.4BSD-lite2
wrong vp's ops vector being used by changing the VOP_LINK's argument order.
The special-case hack doesn't go far enough and breaks the generic
bypass routine used in some non-leaf filesystems. Pointed out by Kirk
McKusick.
when it is moved to an NFS filesystem from from another filesystem and /bin/mv
failed to set the file ownership during the move.
I believe that this bug is present in STABLE but I have not tested it. The fix
would be the same in STABLE even though the code has changed quite considerably
in CURRENT.
the problem "when a file is truncated on the server after being written on
a client under NFSv3, the client doesn't see the size drop to zero".
(As you noted, the problem is that NMODIFIED wasn't being cleared by nfs_close
when it flushed the buffers. After checking through the code, the only place
where NMODIFIED was used to test for the possibility of dirty blocks was in
nfs_setattr(). The two cases are safe to do when there aren't dirty blocks,
so I just took out the tests. Unfortunately, testing for
v_dirtyblkhd.lh_first being non-null is not sufficient, since there are
times when the code moves blocks to the clean list and then back to the
dirty list.)
Submitted by: rick@snowhite.cis.uoguelph.ca
proc or any VM system structure will have to be rebuilt!!!
Much needed overhaul of the VM system. Included in this first round of
changes:
1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
haspage, and sync operations are supported. The haspage interface now
provides information about clusterability. All pager routines now take
struct vm_object's instead of "pagers".
2) Improved data structures. In the previous paradigm, there is constant
confusion caused by pagers being both a data structure ("allocate a
pager") and a collection of routines. The idea of a pager structure has
escentially been eliminated. Objects now have types, and this type is
used to index the appropriate pager. In most cases, items in the pager
structure were duplicated in the object data structure and thus were
unnecessary. In the few cases that remained, a un_pager structure union
was created in the object to contain these items.
3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
be removed. For instance, vm_object_enter(), vm_object_lookup(),
vm_object_remove(), and the associated object hash list were some of the
things that were removed.
4) simple_lock's removed. Discussion with several people reveals that the
SMP locking primitives used in the VM system aren't likely the mechanism
that we'll be adopting. Even if it were, the locking that was in the code
was very inadequate and would have to be mostly re-done anyway. The
locking in a uni-processor kernel was a no-op but went a long way toward
making the code difficult to read and debug.
5) Places that attempted to kludge-up the fact that we don't have kernel
thread support have been fixed to reflect the reality that we are really
dealing with processes, not threads. The VM system didn't have complete
thread support, so the comments and mis-named routines were just wrong.
We now use tsleep and wakeup directly in the lock routines, for instance.
6) Where appropriate, the pagers have been improved, especially in the
pager_alloc routines. Most of the pager_allocs have been rewritten and
are now faster and easier to maintain.
7) The pagedaemon pageout clustering algorithm has been rewritten and
now tries harder to output an even number of pages before and after
the requested page. This is sort of the reverse of the ideal pagein
algorithm and should provide better overall performance.
8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
have been removed. Some other unnecessary casts have also been removed.
9) Some almost useless debugging code removed.
10) Terminology of shadow objects vs. backing objects straightened out.
The fact that the vm_object data structure escentially had this
backwards really confused things. The use of "shadow" and "backing
object" throughout the code is now internally consistent and correct
in the Mach terminology.
11) Several minor bug fixes, including one in the vm daemon that caused
0 RSS objects to not get purged as intended.
12) A "default pager" has now been created which cleans up the transition
of objects to the "swap" type. The previous checks throughout the code
for swp->pg_data != NULL were really ugly. This change also provides
the rudiments for future backing of "anonymous" memory by something
other than the swap pager (via the vnode pager, for example), and it
allows the decision about which of these pagers to use to be made
dynamically (although will need some additional decision code to do
this, of course).
13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
object" code has been removed. MAP_COPY was undocumented and non-
standard. It was furthermore broken in several ways which caused its
behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
continue to work correctly, but via the slightly different semantics
of MAP_PRIVATE.
14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
threads design can be worked around in other ways. Both #12 and #13
were done to simplify the code and improve readability and maintain-
ability. (As were most all of these changes)
TODO:
1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
this will reduce the vnode pager to a mere fraction of its current size.
2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
information provided by the new haspage pager interface. This will
substantially reduce the overhead by eliminating a large number of
VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
improved to provide both a "behind" and "ahead" indication of
contiguousness.
3) Implement the extended features of pager_haspage in swap_pager_haspage().
It currently just says 0 pages ahead/behind.
4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
via a much more general mechanism that could also be used for disk
striping of regular filesystems.
5) Do something to improve the architecture of vm_object_collapse(). The
fact that it makes calls into the swap pager and knows too much about
how the swap pager operates really bothers me. It also doesn't allow
for collapsing of non-swap pager objects ("unnamed" objects backed by
other pagers).
The version 2 support has been tested (client+server) against FreeBSD-2.0,
IRIX 5.3 and FreeBSD-current (using a loopback mount). The version 2 support
is stable AFAIK.
The version 3 support has been tested with a loopback mount and minimally
against an IRIX 5.3 server. It needs more testing and may have problems.
I have patched amd to support the new variable length filehandles although
it will still only use version 2 of the protocol.
Before booting a kernel with these changes, nfs clients will need to at least
build and install /usr/sbin/mount_nfs. Servers will need to build and
install /usr/sbin/mountd.
NFS diskless support is untested.
Obtained from: Rick Macklem <rick@snowhite.cis.uoguelph.ca>
happen normally when there is heavy write activity to a file since the
vnode isn't locked (NFS plays fast and loose with vnode locks). This change
"fixes" PR#267.
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
- Make a number of filesystems work again when they are statically compiled
(blush)
- FIFOs are no longer optional; ``options FIFO'' removed from distributed
config files.
use it in NFS. This is required both for diskless support and for POSIX
compliance. Note: the support in NFS is only for the local node.
Submitted by: based on work originally done by Yuval Yurom
