the system is out of memory. The daemon does a minimal amount of work that
increases as the system becomes more likely to run out of memory and page in/out.
The default tuning is fairly low in background CPU usage, and sysctl variables
have been added to enable flexable operation. This is an experimental feature
that will likely be changed and improved over time.
of the kernel, and also most of the dynamic parts of the kernel. Additionally,
4MB pages will be allocated for display buffers as appropriate (only.)
The 4MB support for SMP isn't complete, but doesn't interfere with operation
either.
flag wasn't being respected during vref(), et. al. Note that this
isn't the eventual fix for the locking problem. Fine grained SMP
in the VM and VFS code will require (lots) more work.
and b_validend. The changes to vfs_bio.c are a bit ugly but hopefully
can be tidied up later by a slight redesign.
PR: kern/2573, kern/2754, kern/3046 (possibly)
Reviewed by: dyson
the pageout daemon wasn't always being waken up appropriately when the
(cache + free) queues were depleted.
Submitted by: David S. Miller <davem@jenolan.rutgers.edu>
There are various options documented in i386/conf/LINT, there is more to
come over the next few days.
The kernel should run pretty much "as before" without the options to
activate SMP mode.
There are a handful of known "loose ends" that need to be fixed, but
have been put off since the SMP kernel is in a moderately good condition
at the moment.
This commit is the result of the tinkering and testing over the last 14
months by many people. A special thanks to Steve Passe for implementing
the APIC code!
fork. (On my machine, fork is about 240usecs, vfork is 78usecs.)
Implement rfork(!RFPROC !RFMEM), which allows a thread to divorce its memory
from the other threads of a group.
Implement rfork(!RFPROC RFCFDG), which closes all file descriptors, eliminating
possible existing shares with other threads/processes.
Implement rfork(!RFPROC RFFDG), which divorces the file descriptors for a
thread from the rest of the group.
Fix the case where a thread does an exec. It is almost nonsense for a thread
to modify the other threads address space by an exec, so we
now automatically divorce the address space before modifying it.
space. (!)
Have each process use the kernel stack and pcb in the kvm space. Since
the stacks are at a different address, we cannot copy the stack at fork()
and allow the child to return up through the function call tree to return
to user mode - create a new execution context and have the new process
begin executing from cpu_switch() and go to user mode directly.
In theory this should speed up fork a bit.
Context switch the tss_esp0 pointer in the common tss. This is a lot
simpler since than swithching the gdt[GPROC0_SEL].sd.sd_base pointer
to each process's tss since the esp0 pointer is a 32 bit pointer, and the
sd_base setting is split into three different bit sections at non-aligned
boundaries and requires a lot of twiddling to reset.
The 8K of memory at the top of the process space is now empty, and unmapped
(and unmappable, it's higher than VM_MAXUSER_ADDRESS).
Simplity the pmap code to manage process contexts, we no longer have to
double map the UPAGES, this simplifies and should measuably speed up fork().
The following parts came from John Dyson:
Set PG_G on the UPAGES that are now in kernel context, and invalidate
them when swapping them out.
Move the upages object (upobj) from the vmspace to the proc structure.
Now that the UPAGES (pcb and kernel stack) are out of user space, make
rfork(..RFMEM..) do what was intended by sharing the vmspace
entirely via reference counting rather than simply inheriting the mappings.
The typo was detected once apon a time with the -Wunused compile option.
The result was that a block of code for implementing
madvise(.. MADV_SEQUENTIAL..) behavior was "dead" and unused, probably
negating the effect of activating the option.
Reviewed by: dyson
by Alan Cox <alc@cs.rice.edu>, and his description of the problem.
The bug was primarily in procfs_mem, but the mistake likely happened
due to the lack of vm system support for the operation. I added
better support for selective marking of page dirty flags so that
vm_map_pageable(wiring) will not cause this problem again.
The code in procfs_mem is now less bogus (but maybe still a little
so.)
centric rather than VM-centric to fix a problem with errors not being
detectable when the header is read.
Killed exech_map as a result of these changes.
There appears to be no performance difference with this change.
changes, so don't expect to be able to run the kernel as-is (very well)
without the appropriate Lite/2 userland changes.
The system boots and can mount UFS filesystems.
Untested: ext2fs, msdosfs, NFS
Known problems: Incorrect Berkeley ID strings in some files.
Mount_std mounts will not work until the getfsent
library routine is changed.
Reviewed by: various people
Submitted by: Jeffery Hsu <hsu@freebsd.org>
the page to be unbusy, and it caused some algorithmic problems
as a result. There were some other problems with it also, so
this is a general cleanup of the code.
Submitted by: Douglas Crosher <dtc@scrooge.ee.swin.oz.au> and myself.
when allocating memory for network buffers at interrupt time. This is due
to inadequate checking for the new mcl_map. Fixed by merging mb_map and
mcl_map into a single mb_map.
Reviewed by: wollman
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
anymore with the "full" collapse fix that we added about 1yr ago!!! The
code has been removed by optioning it out for now, so we can put it back
in ASAP if any problems are found.
and objects. Previously, "fancy" memory management techniques
such as that used by the M3 RTS would have the tendancy of chopping
up processes allocated memory into lots of little objects. Alan
has come up with some improvements to migtigate the sitution to
the point where even the M3 RTS only has one object for bss and
it's managed memory (when running CVSUP.) (There are still cases where the
situation isn't improved when the system pages -- but this is much much
better for the vast majority of cases.) The system will now be able
to much more effectively merge map entries.
Submitted by: Alan Cox <alc@cs.rice.edu>
also implies VM_PROT_EXEC. We support it that way for now,
since the break system call by default gives VM_PROT_ALL. Now
we have a better chance of coalesing map entries when mixing
mmap/break type operations. This was contributing to excessive
numbers of map entries on the modula-3 runtime system. The
problem is still not "solved", but the situation makes more
sense.
Eventually, when we work on architectures where VM_PROT_READ
is orthogonal to VM_PROT_EXEC, we will have to visit this
issue carefully (esp. regarding security issues.)
maps. Additionally, eliminate the map->hint distortion
associated with useracc. That may/may-not be the "right"
thing to do -- but time will tell.
Submitted by: Partially by Alan Cox <alc@cs.rice.edu>
vm_map_simplify and vm_map_simplify_entry. Make vm_map_simplify_entry
handle wired maps so that we can get rid of vm_map_simplify. Modify
the callers of vm_map_simplify to properly use vm_map_simplify_entry.
Submitted by: Alan Cox <alc@cs.rice.edu>
has the negative effect of disabling some map optimizations. This
patch defers the creation of the object until it needs to be at fault time.
Submitted by: Alan Cox <alc@cs.rice.edu>
