[Purpose of this patch]
As Vaibhav explained in the thread below, tracepoints for irq vectors
are useful.
http://www.spinics.net/lists/mm-commits/msg85707.html
<snip>
The current interrupt traces from irq_handler_entry and irq_handler_exit
provide when an interrupt is handled. They provide good data about when
the system has switched to kernel space and how it affects the currently
running processes.
There are some IRQ vectors which trigger the system into kernel space,
which are not handled in generic IRQ handlers. Tracing such events gives
us the information about IRQ interaction with other system events.
The trace also tells where the system is spending its time. We want to
know which cores are handling interrupts and how they are affecting other
processes in the system. Also, the trace provides information about when
the cores are idle and which interrupts are changing that state.
<snip>
On the other hand, my usecase is tracing just local timer event and
getting a value of instruction pointer.
I suggested to add an argument local timer event to get instruction pointer before.
But there is another way to get it with external module like systemtap.
So, I don't need to add any argument to irq vector tracepoints now.
[Patch Description]
Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
But there is an above use case to trace specific irq_vector rather than tracing all events.
In this case, we are concerned about overhead due to unwanted events.
So, add following tracepoints instead of introducing irq_vector_entry/exit.
so that we can enable them independently.
- local_timer_vector
- reschedule_vector
- call_function_vector
- call_function_single_vector
- irq_work_entry_vector
- error_apic_vector
- thermal_apic_vector
- threshold_apic_vector
- spurious_apic_vector
- x86_platform_ipi_vector
Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty
makes a zero when tracepoints are disabled. Detailed explanations are as follows.
- Create trace irq handlers with entering_irq()/exiting_irq().
- Create a new IDT, trace_idt_table, at boot time by adding a logic to
_set_gate(). It is just a copy of original idt table.
- Register the new handlers for tracpoints to the new IDT by introducing
macros to alloc_intr_gate() called at registering time of irq_vector handlers.
- Add checking, whether irq vector tracing is on/off, into load_current_idt().
This has to be done below debug checking for these reasons.
- Switching to debug IDT may be kicked while tracing is enabled.
- On the other hands, switching to trace IDT is kicked only when debugging
is disabled.
In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being
used for other purposes.
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Starting with win8, vmbus interrupts can be delivered on any VCPU in the guest
and furthermore can be concurrently active on multiple VCPUs. Support this
interrupt delivery model by setting up a separate IDT entry for Hyper-V vmbus.
interrupts. I would like to thank Jan Beulich <JBeulich@suse.com> and
Thomas Gleixner <tglx@linutronix.de>, for their help.
In this version of the patch, based on the feedback, I have merged the IDT
vector for Xen and Hyper-V and made the necessary adjustments. Furhermore,
based on Jan's feedback I have added the necessary compilation switches.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1359940959-32168-3-git-send-email-kys@microsoft.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Clean up the hypervisor layer and the hypervisor drivers, using an ops
structure instead of an enumeration with if statements.
The identity of the hypervisor, if needed, can be tested by testing
the pointer value in x86_hyper.
The MS-HyperV private state is moved into a normal global variable
(it's per-system state, not per-CPU state). Being a normal bss
variable, it will be left at all zero on non-HyperV platforms, and so
can generally be tested for HyperV-specific features without
additional qualification.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Greg KH <greg@kroah.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Ky Srinivasan <ksrinivasan@novell.com>
LKML-Reference: <4BE49778.6060800@zytor.com>
This patch integrates HyperV detection within the framework currently
used by VmWare. With this patch, we can avoid having to replicate the
HyperV detection code in each of the Microsoft HyperV drivers.
Reworked and tweaked by Greg K-H to build properly.
Signed-off-by: K. Y. Srinivasan <ksrinivasan@novell.com>
LKML-Reference: <20100506190841.GA1605@kroah.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Vadim Rozenfeld <vrozenfe@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
