to information from a single process causes hangs. Specifically, this
fixes problems (hangs) with concurrent ps commands, when the system is under
heavy memory load.
Reviewed by: davidg
but not there. The extent of the object lock is expanded to be over the
range that it is needed. Additionally, clean up the code so that it conforms
to better coding style.
Testing with the high frequency of 20000 Hz (to find problems) only found
the problem that this frequency is too high for slow i386's.
Disable interrupts while setting the timer frequency. This was unnecessary
before rev.1.57 and forgotten in rev.1.57. The critical (i8254) interrupts
are disabled in another way at boot time but not in the sysctl to change
the frequency.
sleeps before being swapped out. The time is increased from 4 secs to
10 secs. Originally I had decreased it from 20 to 4, but that is a bit
severe. 20 is too long though.
The i386 pmap module uses a special area of kernel virtual memory for mapping
of page tables pages when it needs to modify another process's virtual
address space. It's called the 'alternate page table map'. There is only one
of them and it's expected that only one process will be using it at once and
that the operation is atomic.
When the merged VM/buffer cache was implemented over a year ago, it became
necessary to rundown VM pages at I/O completion. The unfortunate and
unforeseen side effect of this is that pmap functions are now called at bio
interrupt time. If there happend to be a process using the alternate page
table map when this I/O completion occurred, it was possible for a different
process's address space to be switched into the alternate page table map -
leaving the current pmap process with the wrong address space mapped when
the interrupt completed. This resulted in BAD things happening like pages
being mapped or removed from the wrong address space, etc.. Since a very
common case of a process modifying another process's address space is during
fork when the kernel stack is inserted, one of the most common manifestations
of this bug was the kernel stack not being mapped properly, resulting in a
silent hang or reboot. This made it VERY difficult to troubleshoot this bug
(I've been trying to figure out the cause of this for >6 months). Fortunately,
the set of conditions that must be true before this problem occurs is
sufficiently rare enough that most people never saw the bug occur. As I/O
rates increase, however, so does the frequency of the crashes. This problem
used to kill wcarchive about every 10 days, but in more recent times when
the traffic exceeded >100GB/day, the machine could barely manage 6 hours of
uptime.
The fix is to make certain that no process has the pages mapped that are
involved in the I/O, before the I/O is started. The pages are made busy, so
no process will be able to map them, either, until the I/O has finished.
This side-steps the issue by still allowing the pmap functions to be called
at interrupt time, but also assuring that the alternate page table map won't
be switched.
Unfortunately, this appears to not be the only cause of this problem. :-(
Reviewed by: dyson
was due to non-aligned 64K transfers taking 17 pages. We currently
do not support >16 page transfers. The transfer is unfortunately truncated,
but since buffers are usually malloced, this is a problem only once in
a while. Savecore is a culprit, but tar/cpio usually aren't. This
is NOT the final fix (which is likely a bouncing scheme), but will at
least keep the system from crashing.
Re-enables the RSS limiting, and the routine is now tail-recursive,
making it much more safe (eliminates the possiblity of kernel stack
overflow.) Also, the RSS limiting is a little more intelligent about
finding the likely objects that are pushing the process over the limit.
Added some sysctls that help with VM system tuning.
New sysctl features:
1) Enable/disable lru pageout algorithm.
vm.pageout_algorithm = 0, default algorithm that works
well, especially using X windows and heavy
memory loading. Can have adverse effects,
sometimes slowing down program loading.
vm.pageout_algorithm = 1, close to true LRU. Works much
better than clock, etc. Does not work as well as
the default algorithm in general. Certain memory
"malloc" type benchmarks work a little better with
this setting.
Please give me feedback on the performance results
associated with these.
2) Enable/disable swapping.
vm.swapping_enabled = 1, default.
vm.swapping_enabled = 0, useful for cases where swapping
degrades performance.
The config option "NO_SWAPPING" is still operative, and
takes precedence over the sysctl. If "NO_SWAPPING" is
specified, the sysctl still exists, but "vm.swapping_enabled"
is hard-wired to "0".
Each of these can be changed "on the fly."
too late to be used in all cases. It should probably be created (early)
in bsd.kmod.mk for all LKMs.
Use cc instead of cpp | as for the same reasons as in the kernel makefile.
CFLAGS isn't split up as well as in the kernel makefile, but cc doesn't
pass compiler warning flags to cpp, so there is no need to split it.
Fixed profiling of system times. It was pre-4.4Lite and didn't support
statclocks. System times were too small by a factor of 8.
Handle deferred profiling ticks the 4.4Lite way: use addupc_task() instead
of addupc(). Call addupc_task() directly instead of using the ADDUPC()
macro.
Removed vestigial support for PROFTIMER.
switch.s:
Removed addupc().
resourcevar.h:
Removed ADDUPC() and declarations of addupc().
cpu.h:
Updated a comment. i386's never were tahoe's, and the deferred profiling
tick became (possibly) multiple ticks in 4.4Lite.
Obtained from: mostly from NetBSD
multiplication in addupc() overflowed for addresses >= 256K, assuming
the usual profil(2) scale parameter of 0x8000. addupc() will go away
soon.
Submitted by: John Polstra <jdp@polstra.com>
via an ioctl (MOUSE_ACTION).
Fixed a couple of bugs (destructive cursor, uncut, jitter).
Now applications can use the mouse via the MOUSE_MODE ioctl, its
possible to have a signal sent on mouseevents, makeing an event loop
in the application take over mouseevents.
Reviewed by: phk
Reject the addition of rules that will never match (for example,
1.2.3.4:255.255.255.0). User level utilities specify the policy by either
masking the IP address for the user (as ipfw(8) does) or rejecting the
entry with an error. In either case, the kernel should not modify chain
entries to make them work.
media in all cases.
Remove SCSI_2_MAX_DENSITY_CODE definition and rely on the device to tell
us if we attempt an invalid setting.
Closes PR 1245.
Submitted by: fredriks@mcs.com a few changes by me.
LKM'ness. ACTUALLY_LKM_NOT_KERNEL is supposed to be so ugly that it
only gets used until <machine/conf.h> goes away. bsd.kmod.mk should
define a better-named general macro for this. Some places use
PSEUDO_LKM. This is another bad name.
Makefile:
Added IPFIREWALL_VERBOSE_LIMIT option (commented out).
