the last accessed datum is moved to the root of the splay tree.
Therefore, on lookups in which the hint resulted in O(1) access,
the splay tree still achieves O(1) access. In contrast, on lookups
in which the hint failed miserably, the splay tree achieves amortized
logarithmic complexity, resulting in dramatic improvements on vm_maps
with a large number of entries. For example, the execution time
for replaying an access log from www.cs.rice.edu against the thttpd
web server was reduced by 23.5% due to the large number of files
simultaneously mmap()ed by this server. (The machine in question has
enough memory to cache most of this workload.)
Nothing comes for free: At present, I see a 0.2% slowdown on "buildworld"
due to the overhead of maintaining the splay tree. I believe that
some or all of this can be eliminated through optimizations
to the code.
Developed in collaboration with: Juan E Navarro <jnavarro@cs.rice.edu>
Reviewed by: jeff
that td_intr_nesting_level is 0 (like malloc() does). Since malloc() calls
uma we can probably remove the check in malloc() for this now. Also,
perform an extra witness check in that case to make sure we don't hold
any locks when performing a M_WAITOK allocation.
release Giant around vm_map_madvise()'s call to pmap_object_init_pt().
o Replace GIANT_REQUIRED in vm_object_madvise() with the acquisition
and release of Giant.
o Remove the acquisition and release of Giant from madvise().
several reasons before. Fixing it involved restructuring the generic hash
code to require calling code to handle locking, unlocking, and freeing hashes
on error conditions.
vm_object_deallocate(), replacing the assertion GIANT_REQUIRED.
o Remove GIANT_REQUIRED from vm_map_protect() and vm_map_simplify_entry().
o Acquire and release Giant around vm_map_protect()'s call to pmap_protect().
Altogether, these changes eliminate the need for mprotect() to acquire
and release Giant.
mallochash. Mallochash is going to go away as soon as I introduce the
kfree/kmalloc api and partially overhaul the malloc wrapper. This can't happen
until all users of the malloc api that expect memory to be aligned on the size
of the allocation are fixed.
Implement the following checks on freed memory in the bucket path:
- Slab membership
- Alignment
- Duplicate free
This previously was only done if we skipped the buckets. This code will slow
down INVARIANTS a bit, but it is smp safe. The checks were moved out of the
normal path and into hooks supplied in uma_dbg.
0xdeadc0de and then check for it just before memory is handed off as part
of a new request. This will catch any post free/pre alloc modification of
memory, as well as introduce errors for anything that tries to dereference
it as a pointer.
This code takes the form of special init, fini, ctor and dtor routines that
are specificly used by malloc. It is in a seperate file because additional
debugging aids will want to live here as well.
mutex class. Currently this is only used for kmapentzone because kmapents
are are potentially allocated when freeing memory. This is not dangerous
though because no other allocations will be done while holding the
kmapentzone lock.
i386/ia64/alpha - catch up to sparc64/ppc:
- replace pmap_kernel() with refs to kernel_pmap
- change kernel_pmap pointer to (&kernel_pmap_store)
(this is a speedup since ld can set these at compile/link time)
all platforms (as suggested by jake):
- gc unused pmap_reference
- gc unused pmap_destroy
- gc unused struct pmap.pm_count
(we never used pm_count - we track address space sharing at the vmspace)
in the same style as sys/proc.h.
o Undo the de-inlining of several trivial, MPSAFE methods on the vm_map.
(Contrary to the commit message for vm_map.h revision 1.66 and vm_map.c
revision 1.206, de-inlining these methods increased the kernel's size.)
due to conditions that suggest the possible need for stack growth.
This has two beneficial effects: (1) we can
now remove calls to vm_map_growstack() from the MD trap handlers and (2)
simple page faults are faster because we no longer unnecessarily perform
vm_map_growstack() on every page fault.
o Remove vm_map_growstack() from the i386's trap_pfault().
o Remove the acquisition and release of Giant from i386's trap_pfault().
(vm_fault() still acquires it.)
statclock can access it in the tail end of statclock_process() at an
unfortunate time. This bit me several times on an SMP alpha (UP2000)
and the problem went away with this change. I'm not sure why it doesn't
break x86 as well. Maybe it's because the clocks are much faster
on alpha (HZ=1024 by default).
and pmap_copy_page(). This gets rid of a couple more physical addresses
in upper layers, with the eventual aim of supporting PAE and dealing with
the physical addressing mostly within pmap. (We will need either 64 bit
physical addresses or page indexes, possibly both depending on the
circumstances. Leaving this to pmap itself gives more flexibilitly.)
Reviewed by: jake
Tested on: i386, ia64 and (I believe) sparc64. (my alpha was hosed)
hash while holding the lock on a zone. Fix this by doing the allocation
seperately from the actual hash expansion.
The lock is dropped before the allocation and reacquired before the expansion.
The expansion code checks to see if we lost the race and frees the new hash
if we do. We really never will lose this race because the hash expansion is
single threaded via the timeout mechanism.
