on locking rules to make code easier to understand. locking in
uvm_loananon still needs some work on fringe cases where anon's page
is actually on loan from a uobj.
if uvm_loanentry() returned 0; otherwise, the unlocking would already
have been done by uvmfault_unlockall() call in uvm_loanentry().
Okay'ed by Chuck Silvers
the process dsize for both positive and negative changes. Since atop()
casts its result to a paddr_t (which is unsigned), negative changes in
process data size resulted in unrealistic dsizes being set. Use
"dsize -= atop(-diff)" for a negative diffs. Fixes the "Impossible
process sizes" mentioned on current-users.
Unsigned cast catch and much debugging help from Martin Laubach.
the mapping is:
VM_PAGER_OK 0
VM_PAGER_BAD <unused>
VM_PAGER_FAIL <unused>
VM_PAGER_PEND 0 (see below)
VM_PAGER_ERROR EIO
VM_PAGER_AGAIN EAGAIN
VM_PAGER_UNLOCK EBUSY
VM_PAGER_REFAULT ERESTART
for async i/o requests, it used to be possible for the request to
be convert to sync, and the pager would return VM_PAGER_OK or VM_PAGER_PEND
to indicate whether the caller should perform post-i/o cleanup.
this is no longer allowed; pagers must now return 0 to indicate that
the async i/o was successfully started, and the caller never needs to
worry about doing the post-i/o cleanup.
each of the basic types (anonymous data, executable image, cached files)
and prevent the pagedaemon from reusing a given page if that would reduce
the count of that type of page below a sysctl-setable minimum threshold.
the thresholds are controlled via three new sysctl tunables:
vm.anonmin, vm.vnodemin, and vm.vtextmin. these tunables are the
percentages of pageable memory reserved for each usage, and we do not allow
the sum of the minimums to be more than 95% so that there's always some
memory that can be reused.
failed because we failed to acquire some resource needed to initiate
the pageout (such as failing to lock an indirect buffer) rather than
a hard i/o error. in this case we just want to reactivate the page(s)
so that we'll try to write them again later.
while I'm here, clean up some DIAGNOSTIC code.
space is already torn down in uvmspace_free() when the vmspace
refrence count reaches 0. Move the shmexit() call into uvmspace_free().
Note that there is a beneficial side-effect of deferring the unmap
to uvmspace_free() -- on systems where TLB invalidations are
particularly expensive, the unmapping of the address space won't
have to cause TLB invalidations; uvmspace_free() is going to be
run in a context other than the exiting process's, so the "pmap is
active" test will evaluate to FALSE in the pmap module.
entry in the map. the old code would walk around the end of the linked list,
through the header entry, and keep going from the first map entry until it
found a gap in the map, at which point it would return an error. if the map
had no gaps then it would loop forever. reported by k-abe@cs.utah.edu.
while I'm here, clean up this function a bit.
also, use MIN() instead of min(), since the latter takes arguments of
type "int" but we're passing it values of type "vaddr_t", which can be
a larger size.
Mach VM's now. Specific changes:
- Pages now need not have all of their mappings removed before being
put on the inactive list. They only need to have the "referenced"
attribute cleared. This makes putting pages onto the inactive list
much more efficient. In order to eliminate redundant clearings of
"refrenced", callers of uvm_pagedeactivate() must now do this
themselves.
- When checking the "modified" attribute for a page (for clearing
PG_CLEAN), make sure to only do it if PG_CLEAN is currently set on
the page (saves a potentially expensive pmap operation).
- When scanning the inactive list, if a page is referenced, reactivate
it (this part was actually added in uvm_pdaemon.c,v 1.27). This
now works properly now that pages on the inactive list are allowed to
have mappings.
- When scanning the inactive list and considering a page for freeing,
remove all mappings, and then check the "modified" attribute if the
page is marked PG_CLEAN.
- When scanning the active list, if the page was referenced since its
last sweep by the scanner, don't deactivate it. (This part was
actually added in uvm_pdaemon.c,v 1.28.)
These changes greatly improve interactive performance during
moderate to high memory and I/O load.
amap_free(): Assert that the amap is locked.
amap_share_protect(): Assert that the amap is locked.
amap_wipeout(): Assert that the amap is locked.
uvm_anfree(): Assert that the anon has a reference count of 0 and is
not locked.
uvm_anon_lockloanpg(): Assert that the anon is locked.
anon_pagein(): Assert that the anon is locked.
uvmfault_anonget(): Assert that the anon is locked.
uvm_pagealloc_strat(): Assert that the uobj or the anon is locked
And fix the problems these have uncovered:
amap_cow_now(): Lock the new anon after allocating it, and unref and
unlock it (rather than lock!) before freeing it in case
of an error condition. This should fix a problem reported
by Dan Carosone using cdrecord on an i386 MP kernel.
uvm_fault(): Case1B -- Lock the new anon afer allocating it, and unlock
it later when we unlock the old anon.
Case2 -- Lock the new anon after allocating it, and unlock
it later by passing it to uvmfault_unlockall() (we set anon
to NULL if we're not doing a promote fault).
pending i/os to complete before returning even if PGO_CLEANIT is not
specified. this fixes two races:
(1) NFS write rpcs vs. setattr operations which truncate the file.
if the truncate doesn't wait for pending writes to complete then
a later write rpc completion can undo the effect of the truncate.
this problem has been reported by several people.
(2) write i/os in disk-based filesystem vs. the disk block being
freed by a truncation, allocated to a new file, and written
again with different data. if the disk driver reorders the requests
and does the second i/o first, the old data will clobber the new,
corrupting the new file. I haven't heard of anyone experiencing
this problem yet, but it's fixed now anyway.
doesn't have the exec bit set, we need to have PROT_EXEC set
in order for some expected mmap/mprotect behavior to work, so
do the last bit slightly differently: if udv_attach() fails, and
the protection (NOT maxprot) doens't include PROT_EXEC, then clear
PROT_EXEC from maxprot and try udv_attach() again.
Sigh, mmap really needs to be rototilled.
in the mmap() call. maxprot is used to create device mappings,
and always including PROT_EXEC causes the mapping to fail on the Alpha
when mapping a non-RAM offset of /dev/mem (which may be sparse, so
instruction fetch from there is disallowed).
