a thread is an idle thread, just see if it has the IDLETD
flag set. That flag will probably move to the pflags word
as it's permenent and never chenges for the life of the
system so it doesn't need locking.
file are after snaplock, while other ffs device buffers are before
snaplock in global lock order. By itself, this could cause deadlock
when bdwrite() tries to flush dirty buffers on snapshotted ffs. If,
during the flush, COW activity for snapshot needs to allocate block
and ffs_alloccg() selects the cylinder group that is being written
by bdwrite(), then kernel would panic due to recursive buffer lock
acquision.
Avoid dealing with buffers in bdwrite() that are from other side of
snaplock divisor in the lock order then the buffer being written. Add
new BOP, bop_bdwrite(), to do dirty buffer flushing for same vnode in
the bdwrite(). Default implementation, bufbdflush(), refactors the code
from bdwrite(). For ffs device buffers, specialized implementation is
used.
Reviewed by: tegge, jeff, Russell Cattelan (cattelan xfs org, xfs changes)
Tested by: Peter Holm
X-MFC after: 3 weeks (if ever: it changes ABI)
vnode v_flag. For cluster buffers this would result in dereferencing NULL
b_vp. To prevent the panic, cache relevant vnode flag before calling
bstrategy.
Reported by: Peter Holm, kris
Tested by: Peter Holm
Reviewed by: tegge
Pointy hat to: kib
by vnode. Allow for md thread and the thread that owns lock on vnode
backing the md device to do the write even when runningbufspace is
exhausted.
Tested by: Peter Holm
Reviewed by: tegge
MFC after: 2 weeks
Call vfs_setdirty_locked_object() from vfs_busy_pages() instead of
vfs_setdirty(), thereby eliminating a second acquisition and release
of the same vm object lock.
queues lock to BIO_READ operations. Recent changes to the implementation
of the per-page flags have eliminated the need for the page queues lock
in the other cases.
synchronized by the lock on the object containing the page.
Transition PG_WANTED and PG_SWAPINPROG to use the new field,
eliminating the need for holding the page queues lock when setting
or clearing these flags. Rename PG_WANTED and PG_SWAPINPROG to
VPO_WANTED and VPO_SWAPINPROG, respectively.
Eliminate the assertion that the page queues lock is held in
vm_page_io_finish().
Eliminate the acquisition and release of the page queues lock
around calls to vm_page_io_finish() in kern_sendfile() and
vfs_unbusy_pages().
requires Giant. It is set in bgetvp and cleared in brelvp.
- Create QUEUE_DIRTY_GIANT for dirty buffers that require giant.
- In the buf daemon, only grab giant when processing QUEUE_DIRTY_GIANT and
only if we think there are buffers in that queue.
Sponsored by: Isilon Systems, Inc.
the system when brelse() was called with B_RELBUF set on the buffer. This
could be a problem when the system was low on memory, had many buffers on
QUEUE_EMPTYKVA and started to traverse directories. For each getnewbuf(),
pages were allocated from the system, driving the free reserve downwards.
For each brelse(), the system put the buffer on QUEUE_CLEAN, with B_INVAL
set.
This commit changes the semantics of B_RELBUF to also free pages from
non-VMIO buffers.
Reviewed by: alc
- provide an interface (macros) to the page coloring part of the VM system,
this allows to try different coloring algorithms without the need to
touch every file [1]
- make the page queue tuning values readable: sysctl vm.stats.pagequeue
- autotuning of the page coloring values based upon the cache size instead
of options in the kernel config (disabling of the page coloring as a
kernel option is still possible)
MD changes:
- detection of the cache size: only IA32 and AMD64 (untested) contains
cache size detection code, every other arch just comes with a dummy
function (this results in the use of default values like it was the
case without the autotuning of the page coloring)
- print some more info on Intel CPU's (like we do on AMD and Transmeta
CPU's)
Note to AMD owners (IA32 and AMD64): please run "sysctl vm.stats.pagequeue"
and report if the cache* values are zero (= bug in the cache detection code)
or not.
Based upon work by: Chad David <davidc@acns.ab.ca> [1]
Reviewed by: alc, arch (in 2004)
Discussed with: alc, Chad David, arch (in 2004)
- Prefer '_' to ' ', as it results in more easily parsed results in
memory monitoring tools such as vmstat.
- Remove punctuation that is incompatible with using memory type names
as file names, such as '/' characters.
- Disambiguate some collisions by adding subsystem prefixes to some
memory types.
- Generally prefer lower case to upper case.
- If the same type is defined in multiple architecture directories,
attempt to use the same name in additional cases.
Not all instances were caught in this change, so more work is required to
finish this conversion. Similar changes are required for UMA zone names.
Add a new private thread flag to indicate that the thread should
not sleep if runningbufspace is too large.
Set this flag on the bufdaemon and syncer threads so that they skip
the waitrunningbufspace() call in bufwrite() rather than than
checking the proc pointer vs. the known proc pointers for these two
threads. A way of preventing these threads from being starved for
I/O but still placing limits on their outstanding I/O would be
desirable.
Set this flag in ffs_copyonwrite() to prevent bufwrite() calls from
blocking on the runningbufspace check while holding snaplk. This
prevents snaplk from being held for an arbitrarily long period of
time if runningbufspace is high and greatly reduces the contention
for snaplk. The disadvantage is that ffs_copyonwrite() can start
a large amount of I/O if there are a large number of snapshots,
which could cause a deadlock in other parts of the code.
Call runningbufwakeup() in ffs_copyonwrite() to decrement runningbufspace
before attempting to grab snaplk so that I/O requests waiting on
snaplk are not counted in runningbufspace as being in-progress.
Increment runningbufspace again before actually launching the
original I/O request.
Prior to the above two changes, the system could deadlock if enough
I/O requests were blocked by snaplk to prevent runningbufspace from
falling below lorunningspace and one of the bawrite() calls in
ffs_copyonwrite() blocked in waitrunningbufspace() while holding
snaplk.
See <http://www.holm.cc/stress/log/cons143.html>
bio may have been freed and reassigned by the wakeup before being
tested after releasing the bdonelock.
There's a non-zero chance this is the cause of a few of the crashes
knocking around with biodone() sitting in the stack backtrace.
Reviewed By: phk@
make the b_iodone callback responsible for setting it if it is needed.
Previously, it was set unconditionally by bufdone() without holding
whichever lock is shared by the b_iodone callback and the corresponding
top-half function. Consequently, in a race, the top-half function could
conclude that operation was done before the b_iodone callback finished.
See, for example, aio_physwakeup() and aio_fphysio().
Note: I don't believe that the other, more widely-used b_iodone callbacks
are affected.
Discussed with: jeff
Reviewed by: phk
MFC after: 2 weeks
atomic write request, it can fill the buffer cache with the entirety
of that write in order to handle retries. However, it never drops
the vnode lock, or else it wouldn't be atomic, so it ends up waiting
indefinitely for more buf memory that cannot be gotten as it has it
all, and it waits in an uncancellable state.
To fix this, hibufspace is exported and scaled to a reasonable
fraction. This is used as the limit of how much of an atomic write
request by the NFS client will be handled asynchronously. If the
request is larger than this, it will be turned into a synchronous
request which won't deadlock the system. It's possible this value is
far off from what is required by some, so it shall be tunable as soon
as mount_nfs(8) learns of the new field.
The slowdown between an asynchronous and a synchronous write on NFS
appears to be on the order of 2x-4x.
General nod by: gad
MFC after: 2 weeks
More testing: wes
PR: kern/79208
milliseconds due to what is essentially n^2 algorithmic complexity. This
change makes the algorithm N*2 instead. This heavy processing manifested
itself as skipping in audio and video playback due to the long scheduling
latencies and contention on giant by pcm.
- flushbufqueues() is now responsible for flushing multiple buffers
rather than one at a time. This allows us to save our progress in the
list by using a sentinal. We must do the numdirtywakeup() and
waitrunningbufspace() here now rather than in buf_daemon().
- Also add a uio_yield() after we have processed the list once for bufs
without deps and again for bufs with deps. This is to release Giant
and allow any other giant locked code to proceed.
Tested by: Many users on current@
Revealed by: schedgraph traces sent by Emil Mikulic & Anthony Ginepro
Give FFS vnodes a specific bufwrite method which contains all the
background write stuff and then calls into the default bufwrite()
for the rest of the job.
Remove all the background write related stuff from the normal bufwrite.
This drags the softdep_move_dependencies() back into FFS.
Long term, it is worth looking at simply copying the data into
allocated memory and issuing the bio directly and not create the
"shadow buf" in the first place (just like copy-on-write is done
in snapshots for instance). I don't think we really gain anything
but complexity from doing this with a buf.
- Remove some KASSERTs which are invalid if the appropriate lock is
not held.
- Slightly restructure bremfree() so that it is more sane.
- Change the flush code in bdwrite() to avoid acquiring a mutex
whenever possible.
- Change the flush code in bdwrite() to avoid holding the bufobj mutex
while calling buf_countdeps(). This introduces a lock-order
relationship with the softdep lock that can not otherwise be resolved.
- Don't set B_DONE until bufdone() is complete, otherwise another
processor may believe the buf is done before it is.
- Only acquire Giant if the caller has set b_iodone. Don't grab giant
around normal bufdone() calls.
Sponsored By: Isilon Systems, Inc.
I'm not sure why a credential was added to these in the first place, it is
not used anywhere and it doesn't make much sense:
The credentials for syncing a file (ability to write to the
file) should be checked at the system call level.
Credentials for syncing one or more filesystems ("none")
should be checked at the system call level as well.
If the filesystem implementation needs a particular credential
to carry out the syncing it would logically have to the
cached mount credential, or a credential cached along with
any delayed write data.
Discussed with: rwatson
setting the B_REMFREE flag in the buf. This is done to prevent lock order
reversals with code that must call bremfree() with a local lock held.
This also reduces overhead by removing two lock operations per buf for
fsync() and similar.
- Check for the B_REMFREE flag in brelse() and bqrelse() after the bqlock
has been acquired so that we may remove ourself from the free-list.
- Provide a bremfreef() function to immediately remove a buf from a
free-list for use only by NFS. This is done because the nfsclient code
overloads the b_freelist queue for its own async. io queue.
- Simplify the numfreebuffers accounting by removing a switch statement
that executed the same code in every possible case.
- getnewbuf() can encounter locked bufs on free-lists once Giant is removed.
Remove a panic associated with this condition and delay asserts that
inspect the buf until after it is locked.
Reviewed by: phk
Sponsored by: Isilon Systems, Inc.
need for most calls to vm_page_busy(). Specifically, most calls to
vm_page_busy() occur immediately prior to a call to vm_page_remove().
In such cases, the containing vm object is locked across both calls.
Consequently, the setting of the vm page's PG_BUSY flag is not even
visible to other threads that are following the synchronization
protocol.
This change (1) eliminates the calls to vm_page_busy() that
immediately precede a call to vm_page_remove() or functions, such as
vm_page_free() and vm_page_rename(), that call it and (2) relaxes the
requirement in vm_page_remove() that the vm page's PG_BUSY flag is
set. Now, the vm page's PG_BUSY flag is set only when the vm object
lock is released while the vm page is still in transition. Typically,
this is when it is undergoing I/O.
buf->b-dev.
Put a bio between the buf passed to dev_strategy() and the device driver
strategy routine in order to not clobber fields in the buf.
Assert copyright on vfs_bio.c and update copyright message to canonical
text. There is no legal difference between John Dysons two-clause
abbreviated BSD license and the canonical text.
Give ffs it's own bufobj->bo_ops vector and create a private strategy
routine, (currently misnamed for forwards compatibility), which is
just a copy of the generic bufstrategy routine except we call
softdep_disk_prewrite() directly instead of through the buf_prewrite()
indirection.
Teach UFS about the need for softdep_disk_prewrite() and call the
function directly in FFS.
Remove buf_prewrite() from the default bufstrategy() and from the
global bio_ops method vector.
We keep si_bsize_phys around for now as that is the simplest way to pull
the number out of disk device drivers in devfs_open(). The correct solution
would be to do an ioctl(DIOCGSECTORSIZE), but the point is probably mooth
when filesystems sit on GEOM, so don't bother for now.
and release of the global page queues lock required to make the call.
Remove GIANT_REQUIRED from vm_hold_free_pages(). All of its VM operations
are properly synchronized.
Extend it with a strategy method.
Add bufstrategy() which do the usual VOP_SPECSTRATEGY/VOP_STRATEGY
song and dance.
Rename ibwrite to bufwrite().
Move the two NFS buf_ops to more sensible places, add bufstrategy
to them.
Add inlines for bwrite() and bstrategy() which calls through
buf->b_bufobj->b_ops->b_{write,strategy}().
Replace almost all VOP_STRATEGY()/VOP_SPECSTRATEGY() calls with bstrategy().
Initialize b_bufobj for all buffers.
Make incore() and gbincore() take a bufobj instead of a vnode.
Make inmem() local to vfs_bio.c
Change a lot of VI_[UN]LOCK(bp->b_vp) to BO_[UN]LOCK(bp->b_bufobj)
also VI_MTX() to BO_MTX(),
Make buf_vlist_add() take a bufobj instead of a vnode.
Eliminate other uses of bp->b_vp where bp->b_bufobj will do.
Various minor polishing: remove "register", turn panic into KASSERT,
use new function declarations, TAILQ_FOREACH_SAFE() etc.
Add bufobj_wref(), bufobj_wdrop() and bufobj_wwait() to handle the write
count on a bufobj. Bufobj_wdrop() replaces vwakeup().
Use these functions all relevant places except in ffs_softdep.c where
the use if interlocked_sleep() makes this impossible.
Rename b_vnbufs to b_bobufs now that we touch all the relevant files anyway.
of the number of threads which are inside whatever is behind the
cdevsw for this particular cdev.
Make the device mutex visible through dev_lock() and dev_unlock().
We may want finer granularity later.
Replace spechash_mtx use with dev_lock()/dev_unlock().
preparation for integration of p4::phk_bufwork. In the future,
local filesystems will talk to GEOM directly and they will consequently
be able to issue BIO_DELETE directly. Since the removal of the fla
driver, BIO_DELETE has effectively been a no-op anyway.
When avoiding the zeroing of "bogus_page" when it appears in a buf,
be sure to advance the pointers into the data for successive pages.
The bug caused file corruption when read(2)ing from a "hole" in a
file where a previous page of the read block had already been faulted
in: fsx tripped up on this pretty quickly. The particular access
pattern is probably pretty unusual, so other applications probably
wouldn't have had problems, but you'd never know.
Reviewed By: alc@
around in the vnodes surroundings when we allocate a block.
Assign a blocksize when we create a vnode, and yell a warning (and ignore it)
if we got the wrong size.
Please email all such warnings to me.
The big lines are:
NODEV -> NULL
NOUDEV -> NODEV
udev_t -> dev_t
udev2dev() -> findcdev()
Various minor adjustments including handling of userland access to kernel
space struct cdev etc.
allocation and deallocation. This flag's principal use is shortly after
allocation. For such cases, clearing the flag is pointless. The only
unusual use of PG_ZERO is in vfs_bio_clrbuf(). However, allocbuf() never
requests a prezeroed page. So, vfs_bio_clrbuf() never sees a prezeroed
page.
Reviewed by: tegge@
silences an annoying warning in getblk() when VMIO'ing on a directory
vnode, which can happen when vfs.vmiodirenable is 1.
Bring the warning message in line with reality at the same time.
Submitted by: hmp
were a rather overwhelming task. I soon learned that if you don't know
where you're going to store something, at least try to pile it next to
something slightly related in the hope that a pattern emerges.
Apply the same principle to the ffs/snapshot/softupdates code which have
leaked into specfs: Add yet a buf-quasi-method and call it from the
only two places I can see it can make a difference and implement the
magic in ffs_softdep.c where it belongs.
It's not pretty, but at least it's one less layer violated.
This is what we came here for: Hang dev_t's from their cdevsw,
refcount cdevsw and dev_t and generally keep track of things a lot
better than we used to:
Hold a cdevsw reference around all entrances into the device driver,
this will be necessary to safely determine when we can unload driver
code.
Hold a dev_t reference while the device is open.
KASSERT that we do not enter the driver on a non-referenced dev_t.
Remove old D_NAG code, anonymous dev_t's are not a problem now.
When destroy_dev() is called on a referenced dev_t, move it to
dead_cdevsw's list. When the refcount drops, free it.
Check that cdevsw->d_version is correct. If not, set all methods
to the dead_*() methods to prevent entrance into driver. Print
warning on console to this effect. The device driver may still
explode if it is also incompatible with newbus, but in that case
we probably didn't get this far in the first place.
accurate reporting of multi-terabyte filesystem sizes.
You should build and boot a new kernel BEFORE doing a `make world'
as the new kernel will know about binaries using the old statfs
structure, but an old kernel will not know about the new system
calls that support the new statfs structure. Running an old kernel
after a `make world' will cause programs such as `df' that do a
statfs system call to fail with a bad system call.
Reviewed by: Bruce Evans <bde@zeta.org.au>
Reviewed by: Tim Robbins <tjr@freebsd.org>
Reviewed by: Julian Elischer <julian@elischer.org>
Reviewed by: the hoards of <arch@freebsd.org>
Sponsored by: DARPA & NAI Labs.
consistency initialized. Consequently, a number of conditionals that
checked the validity of b_object before passing it to VM_OBJECT_LOCK()
and VM_OBJECT_UNLOCK() are no longer needed.
waitrunningbufspace() calls so that they are always able to
proceed and clean up buffer space.
Submitted by: Brian Fundakowski Feldman <green@freebsd.org>
