being defined, define and use a new MD macro, cpu_spinwait(). It only
expands to something on i386 and amd64, so the compiled code should be
identical.
Name of the macro found by: jhb
Reviewed by: jhb
pic_eoi_source() into one call. This halves the number of spinlock operations
and indirect function calls in the normal case of handling a normal (ithread)
interrupt. Optimize the atpic and ioapic drivers to use inlines where
appropriate in supporting the intr_execute_handlers() change.
This knocks 900ns, or roughly 1350 cycles, off of the time spent servicing an
interrupt in the common case on my 1.5GHz P4 uniprocessor system. SMP systems
likely won't see as much of a gain due to the ioapic being more efficient than
the atpic. I'll investigate porting this to amd64 soon.
Reviewed by: jhb
their own directory and module, leaving the MD parts in the MD
area (the MD parts _are_ part of the modules). /dev/mem and /dev/io
are now loadable modules, thus taking us one step further towards
a kernel created entirely out of modules. Of course, there is nothing
preventing the kernel from having these statically compiled.
- Enable recursion on the page queues lock. This allows calls to
vm_page_alloc(VM_ALLOC_NORMAL) and UMA's obj_alloc() with the page
queues lock held. Such calls are made to allocate page table pages
and pv entries.
- The previous change enables a partial reversion of vm/vm_page.c
revision 1.216, i.e., the call to vm_page_alloc() by vm_page_cowfault()
now specifies VM_ALLOC_NORMAL rather than VM_ALLOC_INTERRUPT.
- Add partial locking to pmap_copy(). (As a side-effect, pmap_copy()
should now be faster on i386 SMP because it no longer generates IPIs
for TLB shootdown on the other processors.)
- Complete the locking of pmap_enter() and pmap_enter_quick(). (As of now,
all changes to a user-level pmap on alpha, amd64, and i386 are performed
with appropriate locking.)
dereference curthread. It is called only from critical_{enter,exit}(),
which already dereferences curthread. This doesn't seem to affect SMP
performance in my benchmarks, but improves MySQL transaction throughput
by about 1% on UP on my Xeon.
Head nodding: jhb, bmilekic
the thread ID and call db_trace_thread().
Since arm has all the logic in db_stack_trace_cmd(), rename the
new DB_COMMAND function to db_stack_trace to avoid conflicts on
arm.
While here, have db_stack_trace parse its own arguments so that
we can use a more natural radix for IDs. If the ID is not a thread
ID, or more precisely when no thread exists with the ID, try if
there's a process with that ID and return the first thread in it.
This makes it easier to print stack traces from the ps output.
requested by: rwatson@
tested on: amd64, i386, ia64
a fast interrupt handler doing an swi_sched(). This fixed the lockups I
saw on my laptop when using xmms in KDE and on rwatson's MySQL benchmarks
on SMP. This will eventually be removed and/or modified when I figure out
what the root cause is and fix that.
pmap_remove_page(). The reason being that pmap_pte_quick() requires
the page queues lock, which is already held, rather than Giant.
- Assert that the page queues lock is held in pmap_remove_page() and
pmap_remove_pte().
future:
rename ttyopen() -> tty_open() and ttyclose() -> tty_close().
We need the ttyopen() and ttyclose() for the new generic cdevsw
functions for tty devices in order to have consistent naming.
pmap_protect() and pmap_remove(). In general, they require the lock in
order to modify a page's pv list or flags. In some cases, however,
pmap_protect() can avoid acquiring the lock.
for unknown events.
A number of modules return EINVAL in this instance, and I have left
those alone for now and instead taught MOD_QUIESCE to accept this
as "didn't do anything".
pmap_remove_pages(). (The implementation of pmap_remove_pages() is
optional. If pmap_remove_pages() is unimplemented, the acquisition and
release of the page queues lock is unnecessary.)
Remove spl calls from the alpha, arm, and ia64 pmap_remove_pages().
a problem that could also be fixed differently without reverting previous
attempts to fix DELAY while the debugger is active (rev 1.204). The bug
was that the i8254 implements a countdown timer, while for (k)db_active
a countup timer was implemented. This resulted in premature termination
and consequently the breakage of DELAY. The fix (relative to rev 1.211)
is to implement a countdown timer for the kdb_active case. As such the
ability to step clock initialization is preserved and DELAY does what is
expected of it.
Blushed: bde :-)
Submitted by: bde
Most of the changes are a direct result of adding thread awareness.
Typically, DDB_REGS is gone. All registers are taken from the
trapframe and backtraces use the PCB based contexts. DDB_REGS was
defined to be a trapframe on all platforms anyway.
Thread awareness introduces the following new commands:
thread X switch to thread X (where X is the TID),
show threads list all threads.
The backtrace code has been made more flexible so that one can
create backtraces for any thread by giving the thread ID as an
argument to trace.
With this change, ia64 has support for breakpoints.
o Make debugging code conditional upon KDB instead of DDB.
o Declare ksym_start and ksym_end as extern and initialize them.
This was previously and bogusly handled by DDB itself.
o Call kdb_enter() instead of Debugger().
o Remove implementation of Debugger().
debugger is not active. The fixes breakages of DELAY() when
running in the debugger, because not calling getit() when the
debugger is active yields a DELAY that doesn't.
o s/ddb_on_nmi/kdb_on_nmi/g
o Rename sysctl machdep.ddb_on_nmi to machdep.kdb_on_nmi
o Make debugging support conditional upon KDB instead of DDB.
o Call kdb_reenter() when kdb_active is non-zero.
o Call kdb_trap() to enter the debugger when not already active.
o Update comments accordingly.
o Remove misplaced prototype of kdb_trap().
o Make debugging code conditional upon KDB instead of DDB.
o Call kdb_enter() instead of Debugger().
o Remove local (static) variable in_debugger. Use kdb_active instead.
a PCB from a trapframe for purposes of unwinding the stack. The PCB
is used as the thread context and all but the thread that entered the
debugger has a valid PCB.
This function can also be used to create a context for the threads
running on the CPUs that have been stopped when the debugger got
entered. This however is not done at the time of this commit.
in which multiple (presumably different) debugger backends can be
configured and which provides basic services to those backends.
Besides providing services to backends, it also serves as the single
point of contact for any and all code that wants to make use of the
debugger functions, such as entering the debugger or handling of the
alternate break sequence. For this purpose, the frontend has been
made non-optional.
All debugger requests are forwarded or handed over to the current
backend, if applicable. Selection of the current backend is done by
the debug.kdb.current sysctl. A list of configured backends can be
obtained with the debug.kdb.available sysctl. One can enter the
debugger by writing to the debug.kdb.enter sysctl.
backend improves over the old GDB support in the following ways:
o Unified implementation with minimal MD code.
o A simple interface for devices to register themselves as debug
ports, ala consoles.
o Compression by using run-length encoding.
o Implements GDB threading support.
bootp -> BOOTP
bootp.nfsroot -> BOOTP_NFSROOT
bootp.nfsv3 -> BOOTP_NFSV3
bootp.compat -> BOOTP_COMPAT
bootp.wired_to -> BOOTP_WIRED_TO
- i.e. back out the previous commit. It's already possible to
pxeboot(8) with a GENERIC kernel.
Pointed out by: dwmalone
BOOTP -> bootp
BOOTP_NFSROOT -> bootp.nfsroot
BOOTP_NFSV3 -> bootp.nfsv3
BOOTP_COMPAT -> bootp.compat
BOOTP_WIRED_TO -> bootp.wired_to
This lets you PXE boot with a GENERIC kernel by putting this sort of thing
in loader.conf:
bootp="YES"
bootp.nfsroot="YES"
bootp.nfsv3="YES"
bootp.wired_to="bge1"
or even setting the variables manually from the OK prompt.
When two drivers share an ISA DMA channel, they both call isa_dmainit()
and the second call fails if DIAGNOSTIC is on.
If isa_dmainit() was already called successfully, just return silently.
This only works if both drivers agree on the bounce buffer size,
but since sharing DMA is usually only possible on very special
hardware and then typically only for devices of the same type (which
would have multiple instances of the same device driver), this is
not a problem in practice.
belong in the respective drivers. I've not removed ALL of them, as a
few still haven't moved. I've just removed the ones that aren't used.
# these can be removed from amd64, but I'm having issues getting to
# sledge at the moment for a build.
honor the alignment and boundary constraints in the dma tag when loading
buffers. Previously, these constraints were only honored when allocating
memory via bus_dmamem_alloc(). Now, bus_dmamap_load() will automatically
use bounce buffers when needed.
Also add a set of sysctls to monitor the global busdma stats. These are:
hw.busdma.free_bpages
hw.busdma.reserved_bpages
hw.busdma.active_bpages
hw.busdma.total_bpages
hw.busdma.total_bounced
hw.busdma.total_deferred
than as one-off hacks in various other parts of the kernel:
- Add a function maybe_preempt() that is called from sched_add() to
determine if a thread about to be added to a run queue should be
preempted to directly. If it is not safe to preempt or if the new
thread does not have a high enough priority, then the function returns
false and sched_add() adds the thread to the run queue. If the thread
should be preempted to but the current thread is in a nested critical
section, then the flag TDF_OWEPREEMPT is set and the thread is added
to the run queue. Otherwise, mi_switch() is called immediately and the
thread is never added to the run queue since it is switch to directly.
When exiting an outermost critical section, if TDF_OWEPREEMPT is set,
then clear it and call mi_switch() to perform the deferred preemption.
- Remove explicit preemption from ithread_schedule() as calling
setrunqueue() now does all the correct work. This also removes the
do_switch argument from ithread_schedule().
- Do not use the manual preemption code in mtx_unlock if the architecture
supports native preemption.
- Don't call mi_switch() in a loop during shutdown to give ithreads a
chance to run if the architecture supports native preemption since
the ithreads will just preempt DELAY().
- Don't call mi_switch() from the page zeroing idle thread for
architectures that support native preemption as it is unnecessary.
- Native preemption is enabled on the same archs that supported ithread
preemption, namely alpha, i386, and amd64.
This change should largely be a NOP for the default case as committed
except that we will do fewer context switches in a few cases and will
avoid the run queues completely when preempting.
Approved by: scottl (with his re@ hat)
pv entries per 1GB of user virtual memory. (eg: if we had 1GB file was
mmaped into 30 processes, that would theoretically reduce the KVA demand by
30MB for pv entries. In reality though, we limit pv entries so we don't
have that many at once.)
We used to store the vm_page_t for the page table page. But we recently
had the pa of the ptp, or can calculate it fairly quickly. If we wanted
to avoid the shift/mask operation in pmap_pde(), we could recover the
pa but that means we have to store it for a while.
This does not measurably change performance.
Suggested by: alc
Tested by: alc
This should fix problems with older SMP systems that only have ISA/EISA
IRQs when routing virgin PCI interrupts as well as on other boxes whose
MADT does not have any interrupt override entries for ISA IRQs that are
used to route PCI interrupts even in APIC mode.
- Allow ioapic_set_{nmi,smi,extint}() to be called multiple times on the
same pin so long as the pin's mode is the same as the mode being
requested.
- Add a notion of bus type for the interrupt associated with interrupt pin.
This is needed so that we can force all EISA interrupts to be active high
in the forthcoming ioapic_config_intr().
- Fix a bug for EISA systems that didn't remap IRQs. This would have broken
EISA systems that tried to disable mixed mode for IRQ 0.
in npxsetregs() too. npxsetregs() must overwrite the previous state, and
it is never paired with an npxgetregs() that would defuse the previous
state (since npxgetregs() would have fninit'ed the state, leaving nothing
to do).
PR: 68058 (this should complete the fix)
Tested by: Simon Barner <barner@in.tum.de>
unnecessary because cpu_setregs() and/or npxinit() always sets CR0_TS
during system initialization, and CR0_TS is set in the next statement
(fpstate_drop()) if necessary after system initialization. Setting
it unnecessarily was less than a pessimization since it broke the
invariant that the npx can be used without an npxdna() trap if
fpucurthread is non-null. The broken invariant became harmful when I
added an fnclex to npxdrop().
Removed setting of CR0_MP in exec_setregs(). This was similarly
unnecessary but was harmless.
Updated comments (mainly by removing them). Things are simpler now
that we have cpu_setregs() and don't support a math emulator or pretend
to support not having either a math emulator or an npx.
Removed the ifdef for avoiding setting CR0_NE in the !SMP case in
cpu_setregs(). npx_probe() should reverse the setting if it wants to
force IRQ13 exception handling for testing.
frstor can trap despite it being a control instruction, since it bogusly
checks for pending exceptions in the state that it is overwriting.
This used to be a non-problem because frstor was always paired with a
previous fnsave, and fnsave does an implicit fninit so any pending
exceptions only remain live in the saved state. Now frstor is sometimes
paired with npxdrop() and we must do a little more than just forget
that the npx was used in npxdrop() to avoid a trap later. This is a
non-problem in the FXSR case because fxrstor doesn't do the bogus check.
FXSR is part of SSE, and npxdrop() is only in FreeBSD-5.x, so this bug
only affected old machines running FreeBSD-5.x.
PR: 68058
devclass will be present even if the driver was disabled by a hint. Using
device_get_softc() provides the right info even if it's overkill.
Explained by: jhb
placates gcc which seems to like to complain about -1 being assigned to
an unsigned value. It is well defined and intended, but since signess bugs
are being hunted just change to 0xffffffff.
o Mask the lower 8 bits, not the lower 4 bits for the ai_capabilities word.
All 8 bits are defined and the 0xf was almost certainly a typo.
o Define APM_UNKNOWN to 0xff for emulation layer.
Otherwise, the setting of the PG_M bit by one processor could be lost if
another processor is simultaneously changing the PG_W bit.
Reviewed by: tegge@
present and thus that the PnPBIOS probe should be skipped instead of
having ACPI zero out the PnPBIOStable pointer.
- Make the PnPBIOStable pointer static to i386/i386/bios.c now that that is
the only place it is used.
Dividing by 0 in order to check for irq13/exception16 delivery apparently
always causes an irq13 even if we have configured for exception16 (by
setting CR0_NE). This was expected, but the timing of the irq13 was
unexpected. Without CR0_NE, the irq13 is delivered synchronously at
least on my test machine, but with CR0_NE it is delivered a little
later (about 250 nsec) in PIC mode and much later (5000-10000 nsec)
in APIC mode. So especially in APIC mode, the irq13 may arrive after
it is supposed to be shut down. It should then be masked, but the
shutdown is incomplete, so the irq goes to a null handler that just
reports it as stray. The fix is to wait a bit after dividing by 0 to
give a good chance of the irq13 being handled by its proper handler.
Removed the hack that was supposed to recover from the incomplete shutdown
of irq13. The shutdown is now even more incomplete, or perhaps just
incomplete in a different way, but the hack now has no effect because
irq13 is edge triggered and handling of edge triggered interrupts is
now optimized by skipping their masking. The hack only worked due
to it accidentally not losing races.
The incomplete shutdown of irq13 still allows unprivileged users to
generate a stray irq13 (except on systems where irq13 is actually used)
by unmasking an npx exception and causing one. The exception gets
handled properly by the exception 16 handler. A spurious irq13 is
delivered asynchronously but is harmless (as in the probe) because it
is almost perfectly not handled by the null interrupt handler.
Perfectly not handling it involves mainly not resetting the npx busy
latch. This prevents further irq13's despite them not being masked in
the [A]PIC.
size_t and size_t *, respectively. Update callers for the new interface.
This is a better fix for overflows that occurred when dumping segments
larger than 2GB to core files.
APIC interrupt pin based on the settings in the corresponding interrupt
source structure.
- Use ioapic_program_intpin() in place of manual frobbing of the intpin
configuration in ioapic_program_destination() and ioapic_register().
- Use ioapic_program_intpin() to implement suspend/resume support for I/O
APICs.
mbuma is an Mbuf & Cluster allocator built on top of a number of
extensions to the UMA framework, all included herein.
Extensions to UMA worth noting:
- Better layering between slab <-> zone caches; introduce
Keg structure which splits off slab cache away from the
zone structure and allows multiple zones to be stacked
on top of a single Keg (single type of slab cache);
perhaps we should look into defining a subset API on
top of the Keg for special use by malloc(9),
for example.
- UMA_ZONE_REFCNT zones can now be added, and reference
counters automagically allocated for them within the end
of the associated slab structures. uma_find_refcnt()
does a kextract to fetch the slab struct reference from
the underlying page, and lookup the corresponding refcnt.
mbuma things worth noting:
- integrates mbuf & cluster allocations with extended UMA
and provides caches for commonly-allocated items; defines
several zones (two primary, one secondary) and two kegs.
- change up certain code paths that always used to do:
m_get() + m_clget() to instead just use m_getcl() and
try to take advantage of the newly defined secondary
Packet zone.
- netstat(1) and systat(1) quickly hacked up to do basic
stat reporting but additional stats work needs to be
done once some other details within UMA have been taken
care of and it becomes clearer to how stats will work
within the modified framework.
From the user perspective, one implication is that the
NMBCLUSTERS compile-time option is no longer used. The
maximum number of clusters is still capped off according
to maxusers, but it can be made unlimited by setting
the kern.ipc.nmbclusters boot-time tunable to zero.
Work should be done to write an appropriate sysctl
handler allowing dynamic tuning of kern.ipc.nmbclusters
at runtime.
Additional things worth noting/known issues (READ):
- One report of 'ips' (ServeRAID) driver acting really
slow in conjunction with mbuma. Need more data.
Latest report is that ips is equally sucking with
and without mbuma.
- Giant leak in NFS code sometimes occurs, can't
reproduce but currently analyzing; brueffer is
able to reproduce but THIS IS NOT an mbuma-specific
problem and currently occurs even WITHOUT mbuma.
- Issues in network locking: there is at least one
code path in the rip code where one or more locks
are acquired and we end up in m_prepend() with
M_WAITOK, which causes WITNESS to whine from within
UMA. Current temporary solution: force all UMA
allocations to be M_NOWAIT from within UMA for now
to avoid deadlocks unless WITNESS is defined and we
can determine with certainty that we're not holding
any locks when we're M_WAITOK.
- I've seen at least one weird socketbuffer empty-but-
mbuf-still-attached panic. I don't believe this
to be related to mbuma but please keep your eyes
open, turn on debugging, and capture crash dumps.
This change removes more code than it adds.
A paper is available detailing the change and considering
various performance issues, it was presented at BSDCan2004:
http://www.unixdaemons.com/~bmilekic/netbuf_bmilekic.pdf
Please read the paper for Future Work and implementation
details, as well as credits.
Testing and Debugging:
rwatson,
brueffer,
Ketrien I. Saihr-Kesenchedra,
...
Reviewed by: Lots of people (for different parts)
of this micro-optimization occurs when we call pmap_enter() to wire an
already mapped page. Because of the micro-optimization, we fail to
mark the PTE as wired. Later, on teardown of the address space,
pmap_remove_pages() destroys the PTE before vm_fault_unwire() has
unwired the page. (pmap_remove_pages() is not supposed to destroy
wired PTEs. They are destroyed by a later call to pmap_remove().)
Thus, the page becomes lost.
Note: The page is not lost if the application called munlock(2), only
if it relies on teardown of the address space to unwire its pages.
For the historically inclined, this bug was introduced by a
megacommit, revision 1.182, roughly six years ago.
Leak observed by: green@ and dillon independently
Patch submitted by: dillon at backplane dot com
Reviewed by: tegge@
MFC after: 1 week
been developed for use with FreeBSD, version 4.8 and later.
Submitted by: Hema Joyce
Reviewed by: Prafulla Deuskar
Approved by: Prafulla Deuskar
MFC after: 1 week
gmon and struct gmonhdr was originally just to represent the kernel
(profiling) clock frequency and it remains poorly suited to representing
the frequencies of fast counters like the TSC. It broke a year or two
ago. This quick fix keeps it working for another year or month or two
until TSC frequencies can exceed 2^32, by dividing the frequency by 2.
Dividing the frequency by 4 would work for a little longer but would
lose a little too much precision.
Fixed profiling of trap, syscall and interrupt handlers and some
ordinary functions, essentially by backing out half of rev.1.106 of
i386/exception.s. The handlers must be between certain labels for
the purposes of profiling, and this was broken by scattering them in
separately compiled .s files, especially for ordinary functions that
ended up between the labels. Merge the files by #including them as
before, except with different pathnames and better comments and
organization. Changes to the scattered files are minimal -- just
move the labels to the file that does the #includes.
This also partly fixes profiling of IPIs -- all IPI handlers are now
correctly classified as interrupt handlers, but many are still missing
mcount calls.
vm86bios.s is included as before, but it is now between the labels for
interrupt handlers again, which seems to be wrong since half of it is
for a non-interrupt handler.
polarity rather than assuming that level triggered IRQs use active low and
edge triggered IRQs use active high. Both the MultiProcessor 1.4
and ACPI 2.0 Specifications state in their examples that level triggered
EISA IRQs are active low, but in practice they seem to be active high.
Reported by: Nik Azim Azam nskyline_r35 at yahoo dot com
high resolution kernel profiling (options GUPROF. "U" in GUPROF stands
for microseconds resolution, but the resolution is now smaller than 1
nanosecond on multi-GHz machines and the accuracy is heading towards
1 nanosecond too). Arches that support GUPROF must now provide certain
macros for the calibration. GUPROF is now only supported for i386's,
so the absence of the new macros for other arches doesn't break anything
that wasn't already broken. amd64's have uncommitted support for
GUPROF, and sparc64's have support that seems to be complete except
here (there was an #error for non-i386 cases; now there are undefined
macros).
Changed the asms a little:
- declare them as __volatile. They must not be moved, and exporting a
label across asms is technically incorrect, so try harder to stop gcc
moving them.
- don't put the non-clobbered register "bx" in the clobber list. The
clobber lists are still more conservative than necessary.
- drop the non-support for gcc-1. It just gave a better error message,
and this is not useful since compiling with gcc-1 would cause thousands
of worse error messages.
- drop the support for aout.
to <sys/gmon.h>. Cleaned them up a little by not attempting to ifdef
for incomplete and out of date support for GUPROF in userland, as in
the sparc64 version.
