Iranna D Ankad reported that IBM x3950 systems have boot
problems after this commit:
|
| commit b9c61b7007
|
| x86/pci: update pirq_enable_irq() to setup io apic routing
|
The problem is that with the patch, the machine freezes when
console=ttyS0,... kernel serial parameter is passed.
It seem to freeze at DVD initialization and the whole problem
seem to be DVD/pata related, but somehow exposed through the
serial parameter.
Such apic problems can expose really weird behavior:
ACPI: IOAPIC (id[0x10] address[0xfecff000] gsi_base[0])
IOAPIC[0]: apic_id 16, version 0, address 0xfecff000, GSI 0-2
ACPI: IOAPIC (id[0x0f] address[0xfec00000] gsi_base[3])
IOAPIC[1]: apic_id 15, version 0, address 0xfec00000, GSI 3-38
ACPI: IOAPIC (id[0x0e] address[0xfec01000] gsi_base[39])
IOAPIC[2]: apic_id 14, version 0, address 0xfec01000, GSI 39-74
ACPI: INT_SRC_OVR (bus 0 bus_irq 1 global_irq 4 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 5 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 3 global_irq 6 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 4 global_irq 7 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 6 global_irq 9 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 7 global_irq 10 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 8 global_irq 11 low edge)
ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 12 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 12 global_irq 15 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 13 global_irq 16 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 14 global_irq 17 low edge)
ACPI: INT_SRC_OVR (bus 0 bus_irq 15 global_irq 18 dfl dfl)
It turns out that the system has three io apic controllers, but
boot ioapic routing is in the second one, and that gsi_base is
not 0 - it is using a bunch of INT_SRC_OVR...
So these recent changes:
1. one set routing for first io apic controller
2. assume irq = gsi
... will break that system.
So try to remap those gsis, need to seperate boot_ioapic_idx
detection out of enable_IO_APIC() and call them early.
So introduce boot_ioapic_idx, and remap_ioapic_gsi()...
-v2: shift gsi with delta instead of gsi_base of boot_ioapic_idx
-v3: double check with find_isa_irq_apic(0, mp_INT) to get right
boot_ioapic_idx
-v4: nr_legacy_irqs
-v5: add print out for boot_ioapic_idx, and also make it could be
applied for current kernel and previous kernel
-v6: add bus_irq, in acpi_sci_ioapic_setup, so can get overwride
for sci right mapping...
-v7: looks like pnpacpi get irq instead of gsi, so need to revert
them back...
-v8: split into two patches
-v9: according to Eric, use fixed 16 for shifting instead of remap
-v10: still need to touch rsparser.c
-v11: just revert back to way Eric suggest...
anyway the ioapic in first ioapic is blocked by second...
-v12: two patches, this one will add more loop but check apic_id and irq > 16
Reported-by: Iranna D Ankad <iranna.ankad@in.ibm.com>
Bisected-by: Iranna D Ankad <iranna.ankad@in.ibm.com>
Tested-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Thomas Renninger <trenn@suse.de>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: len.brown@intel.com
LKML-Reference: <4B8A321A.1000008@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Now that both Xen and VMI disable allocations of PTE pages from high
memory this paravirt op serves no further purpose.
This effectively reverts ce6234b5 "add kmap_atomic_pte for mapping
highpte pages".
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1267204562-11844-3-git-send-email-ian.campbell@citrix.com>
Acked-by: Alok Kataria <akataria@vmware.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Preventing HIGHPTE allocations under VMI will allow us to remove the
kmap_atomic_pte paravirt op.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1267204562-11844-2-git-send-email-ian.campbell@citrix.com>
Acked-by: Alok Kataria <akataria@vmware.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
There's a path in the pagefault code where the kernel deliberately
breaks its own locking rules by kmapping a high pte page without
holding the pagetable lock (in at least page_check_address). This
breaks Xen's ability to track the pinned/unpinned state of the
page. There does not appear to be a viable workaround for this
behaviour so simply disable HIGHPTE for all Xen guests.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1267204562-11844-1-git-send-email-ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pasi Kärkkäinen <pasik@iki.fi>
Cc: <stable@kernel.org> # .32.x: 14315592: Allow highmem user page tables to be disabled at boot time
Cc: <stable@kernel.org> # .32.x
Cc: <xen-devel@lists.xensource.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Remove the name field from the arch_hw_breakpoint. We never deal
with target symbols in the arch level, neither do we need to ever
store it. It's a legacy for the previous version of the x86
breakpoint backend.
Let's remove it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Merge commit aef55d4922 mis-merged io_apic.c so we lost the
arch_probe_nr_irqs() method.
This caused subtle boot breakages (udev confusion likely
due to missing drivers) with certain configs.
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20100207210250.GB8256@jenkins.home.ifup.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Enable NMI on all cpus in UV system and add an NMI handler
to dump_stack on each cpu.
By default on x86 all the cpus except the boot cpu have NMI
masked off. This patch enables NMI on all cpus in UV system
and adds an NMI handler to dump_stack on each cpu. This
way if a system hangs we can NMI the machine and get a
backtrace from all the cpus.
Version 2: Use x86_platform driver mechanism for nmi init, per
Ingo's suggestion.
Version 3: Clean up Ingo's nits.
Signed-off-by: Russ Anderson <rja@sgi.com>
LKML-Reference: <20100226164912.GA24439@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'kmemcheck-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
kmemcheck: Test the full object in kmemcheck_is_obj_initialized()
Split amd,p6,intel into separate files so that we can easily deal with
CONFIG_CPU_SUP_* things, needed to make things build now that perf_event.c
relies on symbols from amd.c
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
During switching virtual counters there is access to perfctr msrs. If
the counter is not available this fails due to an invalid
address. This patch fixes this.
Cc: stable@kernel.org
Signed-off-by: Robert Richter <robert.richter@amd.com>
Multiple virtual counters share one physical counter. The reservation
of virtual counters fails due to duplicate allocation of the same
counter. The counters are already reserved. Thus, virtual counter
reservation may removed at all. This also makes the code easier.
Cc: stable@kernel.org
Signed-off-by: Robert Richter <robert.richter@amd.com>
Currently, oprofile fails silently on platforms where a non-OS entity
such as the system firmware "enables" and uses a performance
counter. There is a warning in the code for this case.
The warning indicates an already running counter. If oprofile doesn't
collect data, then try using a different performance counter on your
platform to monitor the desired event. Delete the counter from the
desired event by editing the
/usr/share/oprofile/<cpu_type>/<cpu>/events
file. If the event cannot be monitored by any other counter, contact
your hardware or BIOS vendor.
Cc: Shashi Belur <shashi-kiran.belur@hp.com>
Cc: Tony Jones <tonyj@suse.de>
Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
This patch generates a warning if a counter is already active.
Implemented for AMD and P6 models. P4 is not supported.
Cc: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Cc: Shashi Belur <shashi-kiran.belur@hp.com>
Cc: Tony Jones <tonyj@suse.de>
Signed-off-by: Robert Richter <robert.richter@amd.com>
IBS selects an op (execution operation) for sampling by counting
either cycles or dispatched ops. Better statistical samples can be
produced by adding a software generated random offset to the periodic
op counter value with each sample.
This patch adds software randomization to the IBS periodic op
counter. The lower 12 bits of the 20 bit counter are
randomized. IbsOpCurCnt is initialized with a 12 bit random value.
There is a work around if the hw can not write to IbsOpCurCnt. Then
the lower 8 bits of the 16 bit IbsOpMaxCnt [15:0] value are randomized
in the range of -128 to +127 by adding/subtracting an offset to the
maximum count (IbsOpMaxCnt).
The linear feedback shift register (LFSR) algorithm is used for
pseudo-random number generation to have low impact to the memory
system.
Signed-off-by: Robert Richter <robert.richter@amd.com>
This patch implements a linear feedback shift register (LFSR) for
pseudo-random number generation for IBS.
For IBS measurements it would be good to minimize memory traffic in
the interrupt handler since every access pollutes the data
caches. Computing a maximal period LFSR just needs shifts and ORs.
The LFSR method is good enough to randomize the ops at low
overhead. 16 pseudo-random bits are enough for the implementation and
it doesn't matter that the pattern repeats with a fairly short
cycle. It only needs to break up (hard) periodic sampling behavior.
The logic was designed by Paul Drongowski.
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
This patch adds IBS feature detection using cpuid flags. An IBS
capability mask is introduced to test for certain IBS features. The
bit mask is the same as for IBS cpuid feature flags (Fn8000_001B_EAX),
but bit 0 is used to indicate the existence of IBS.
The patch also changes the handling of the IbsOpCntCtl bit (periodic
op counter count control). The oprofilefs file for this feature
(ibs_op/dispatched_ops) will be only exposed if the feature is
available, also the default for the bit is set to count clock cycles.
In general, the userland can detect the availability of a feature by
checking for the corresponding file in oprofilefs. If it exists, the
feature also exists. This may lead to a dynamic file layout depending
on the cpu type with that the userland has to deal with. Current
opcontrol is compatible.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Standard AMD systems have the same number of nodes as there are
northbridge devices. However, there may kernel configurations
(especially for 32 bit) or system setups exist, where the node number
is different or it can not be detected properly. Thus the check is not
reliable and may fail though IBS setup was fine. For this reason it is
better to remove the check.
Cc: stable <stable@kernel.org>
Signed-off-by: Robert Richter <robert.richter@amd.com>
OProfile support for IBS is now for several versions in the
kernel. The feature is stable now and the code can be activated
permanently.
As a side effect IBS now works also on nosmp configs.
Signed-off-by: Robert Richter <robert.richter@amd.com>
We re-program the event control register every time we reset the count,
this appears to be superflous, hence remove it.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since the cpu argument to hw_perf_group_sched_in() is always
smp_processor_id(), simplify the code a little by removing this argument
and using the current cpu where needed.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1265890918.5396.3.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds correct AMD NorthBridge event scheduling.
NB events are events measuring L3 cache, Hypertransport traffic. They are
identified by an event code >= 0xe0. They measure events on the
Northbride which is shared by all cores on a package. NB events are
counted on a shared set of counters. When a NB event is programmed in a
counter, the data actually comes from a shared counter. Thus, access to
those counters needs to be synchronized.
We implement the synchronization such that no two cores can be measuring
NB events using the same counters. Thus, we maintain a per-NB allocation
table. The available slot is propagated using the event_constraint
structure.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4b703957.0702d00a.6bf2.7b7d@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In certain situations, the kernel may need to stop and start the same
event rapidly. The current PMU callbacks do not distinguish between stop
and release (i.e., stop + free the resource). Thus, a counter may be
released, then it will be immediately re-acquired. Event scheduling will
again take place with no guarantee to assign the same counter. On some
processors, this may event yield to failure to assign the event back due
to competion between cores.
This patch is adding a new pair of callback to stop and restart a counter
without actually release the underlying counter resource. On stop, the
counter is stopped, its values saved and that's it. On start, the value
is reloaded and counter is restarted (on x86, actual restart is delayed
until perf_enable()).
Signed-off-by: Stephane Eranian <eranian@google.com>
[ added fallback to ->enable/->disable for all other PMUs
fixed x86_pmu_start() to call x86_pmu.enable()
merged __x86_pmu_disable into x86_pmu_stop() ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4b703875.0a04d00a.7896.ffffb824@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Replace the #ifdef'ed OLPC-specific init functions by a conditional
x86_init function. If the function returns 0 we leave pci_arch_init,
otherwise we continue.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Andres Salomon <dilinger@collabora.co.uk>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A318CE89@orsmsx508.amr.corp.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Added an abstraction function for arch specific init calls.
Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A318CE84@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The Moorestown platform requires IOAPIC for all interrupts from the
south complex, since there is no legacy PIC.
Furthermore, Moorestown I/O requires PCI. Moorestown PCI depends on PCI MMCONFIG
and DIRECT method to perform device enumeration, as there is no PCI BIOS.
[ hpa: rewrote commit message ]
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
LKML-Reference: <1267120934-9505-1-git-send-email-jacob.jun.pan@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This patch changes the 32-bit version of kernel_physical_mapping_init() to
return the last mapped address like the 64-bit one so that we can unify the
call-site in init_memory_mapping().
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
LKML-Reference: <alpine.DEB.2.00.1002241703570.1180@melkki.cs.helsinki.fi>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
If we don't have any Moorestown CPU support compiled in, we don't need
the Moorestown PCI support either.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4B858E89.7040807@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The NUMAQ initialization sets x86_init.pci.init to pci_numaq_init,
which obviously isn't defined if CONFIG_PCI isn't defined. This
dependency was implicit in the past, because pci_numaq_init was
invoked from arch/x86/pci/legacy.c, which itself was conditioned on
CONFIG_PCI.
I suspect that no NUMA-Q machines without PCI were ever built, so
instead of complicating the code by adding #ifdefs or stub functions,
just disable this bit of the configuration space.
[ hpa: rewrote the checkin comment ]
Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A321EE1F@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Introduce x86 arch-specific optimization code, which supports
both of x86-32 and x86-64.
This code also supports safety checking, which decodes whole of
a function in which probe is inserted, and checks following
conditions before optimization:
- The optimized instructions which will be replaced by a jump instruction
don't straddle the function boundary.
- There is no indirect jump instruction, because it will jumps into
the address range which is replaced by jump operand.
- There is no jump/loop instruction which jumps into the address range
which is replaced by jump operand.
- Don't optimize kprobes if it is in functions into which fixup code will
jumps.
This uses text_poke_multibyte() which doesn't support modifying
code on NMI/MCE handler. However, since kprobes itself doesn't
support NMI/MCE code probing, it's not a problem.
Changes in v9:
- Use *_text_reserved() for checking the probe can be optimized.
- Verify jump address range is in 2G range when preparing slot.
- Backup original code when switching optimized buffer, instead of
preparing buffer, because there can be int3 of other probes in
preparing phase.
- Check kprobe is disabled in arch_check_optimized_kprobe().
- Strictly check indirect jump opcodes (ff /4, ff /5).
Changes in v6:
- Split stop_machine-based jump patching code.
- Update comments and coding style.
Changes in v5:
- Introduce stop_machine-based jump replacing.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Anders Kaseorg <andersk@ksplice.com>
Cc: Tim Abbott <tabbott@ksplice.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133446.6725.78994.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add generic text_poke_smp for SMP which uses stop_machine()
to synchronize modifying code.
This stop_machine() method is officially described at "7.1.3
Handling Self- and Cross-Modifying Code" on the intel's
software developer's manual 3A.
Since stop_machine() can't protect code against NMI/MCE, this
function can not modify those handlers. And also, this function
is basically for modifying multibyte-single-instruction. For
modifying multibyte-multi-instructions, we need another special
trap & detour code.
This code originaly comes from immediate values with
stop_machine() version. Thanks Jason and Mathieu!
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Anders Kaseorg <andersk@ksplice.com>
Cc: Tim Abbott <tabbott@ksplice.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133438.6725.80273.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
commit ff097ddd4 (x86/PCI: MMCONFIG: manage pci_mmcfg_region as a
list, not a table) introduced a nasty memory corruption when
pci_mmcfg_list is empty.
pci_mmcfg_check_end_bus_number() dereferences pci_mmcfg_list.prev even
when the list is empty. The following write hits some variable near to
pci_mmcfg_list.
Further down a similar problem exists, where cfg->list.next is
dereferenced unconditionally and a comparison with some variable near
to pci_mmcfg_list happens.
Add a check for the last element into the for_each_entry() loop and
remove all the other crappy logic which is just a leftover of the old
array based code which was replaced by the list conversion.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: stable@kernel.org
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
The code in stop_machine that modifies the kernel text has a bit
of logic to handle the case of NMIs. stop_machine does not prevent
NMIs from executing, and if an NMI were to trigger on another CPU
as the modifying CPU is changing the NMI text, a GPF could result.
To prevent the GPF, the NMI calls ftrace_nmi_enter() which may
modify the code first, then any other NMIs will just change the
text to the same content which will do no harm. The code that
stop_machine called must wait for NMIs to finish while it changes
each location in the kernel. That code may also change the text
to what the NMI changed it to. The key is that the text will never
change content while another CPU is executing it.
To make the above work, the call to ftrace_nmi_enter() must also
do a smp_mb() as well as atomic_inc(). But for applications like
perf that require a high number of NMIs for profiling, this can have
a dramatic effect on the system. Not only is it doing a full memory
barrier on both nmi_enter() as well as nmi_exit() it is also
modifying a global variable with an atomic operation. This kills
performance on large SMP machines.
Since the memory barriers are only needed when ftrace is in the
process of modifying the text (which is seldom), this patch
adds a "modifying_code" variable that gets set before stop machine
is executed and cleared afterwards.
The NMIs will check this variable and store it in a per CPU
"save_modifying_code" variable that it will use to check if it
needs to do the memory barriers and atomic dec on NMI exit.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Distros generally (I looked at Debian, RHEL5 and SLES11) seem to
enable CONFIG_HIGHPTE for any x86 configuration which has highmem
enabled. This means that the overhead applies even to machines which
have a fairly modest amount of high memory and which therefore do not
really benefit from allocating PTEs in high memory but still pay the
price of the additional mapping operations.
Running kernbench on a 4G box I found that with CONFIG_HIGHPTE=y but
no actual highptes being allocated there was a reduction in system
time used from 59.737s to 55.9s.
With CONFIG_HIGHPTE=y and highmem PTEs being allocated:
Average Optimal load -j 4 Run (std deviation):
Elapsed Time 175.396 (0.238914)
User Time 515.983 (5.85019)
System Time 59.737 (1.26727)
Percent CPU 263.8 (71.6796)
Context Switches 39989.7 (4672.64)
Sleeps 42617.7 (246.307)
With CONFIG_HIGHPTE=y but with no highmem PTEs being allocated:
Average Optimal load -j 4 Run (std deviation):
Elapsed Time 174.278 (0.831968)
User Time 515.659 (6.07012)
System Time 55.9 (1.07799)
Percent CPU 263.8 (71.266)
Context Switches 39929.6 (4485.13)
Sleeps 42583.7 (373.039)
This patch allows the user to control the allocation of PTEs in
highmem from the command line ("userpte=nohigh") but retains the
status-quo as the default.
It is possible that some simple heuristic could be developed which
allows auto-tuning of this option however I don't have a sufficiently
large machine available to me to perform any particularly meaningful
experiments. We could probably handwave up an argument for a threshold
at 16G of total RAM.
Assuming 768M of lowmem we have 196608 potential lowmem PTE
pages. Each page can map 2M of RAM in a PAE-enabled configuration,
meaning a maximum of 384G of RAM could potentially be mapped using
lowmem PTEs.
Even allowing generous factor of 10 to account for other required
lowmem allocations, generous slop to account for page sharing (which
reduces the total amount of RAM mappable by a given number of PT
pages) and other innacuracies in the estimations it would seem that
even a 32G machine would not have a particularly pressing need for
highmem PTEs. I think 32G could be considered to be at the upper bound
of what might be sensible on a 32 bit machine (although I think in
practice 64G is still supported).
It's seems questionable if HIGHPTE is even a win for any amount of RAM
you would sensibly run a 32 bit kernel on rather than going 64 bit.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1266403090-20162-1-git-send-email-ian.campbell@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This will save 64K bytes from memory when loading linux if DMI is
disabled, which is good for embedded systems.
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
LKML-Reference: <1265758732-19320-1-git-send-email-cascardo@holoscopio.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
While probing for the PCI fixed BAR capability in the extended PCI
configuration space we need to make sure raw_pci_ext_ops is
actually initialized.
Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A321E8F7@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Remove duplicated cfg[i].vector assignment.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4B8493A0.6080501@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
nr_legacy_irqs and its ilk have moved to legacy_pic.
-v2: there is one in ioapic_.c
Singed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4B84AAC4.2020204@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Add Moorestown platform clock setup code to the x86_init abstraction.
Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A318D2D4@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Moorestown platform does not have PIT or HPET platform timers. Instead it
has a bank of eight APB timers. The number of available timers to the os
is exposed via SFI mtmr tables. All APB timer interrupts are routed via
ioapic rtes and delivered as MSI.
Currently, we use timer 0 and 1 for per cpu clockevent devices, timer 2
for clocksource.
Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A318D2D2@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
