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Message-ID: <A5ED84D3BB3A384992CBB9C77DEDA4D414A23411@USINDEM103.corp.hds.com>
Date: Tue, 18 Dec 2012 05:05:44 +0000
From: Seiji Aguchi <seiji.aguchi@....com>
To: Steven Rostedt <rostedt@...dmis.org>
CC: "x86@...nel.org" <x86@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"H. Peter Anvin (hpa@...or.com)" <hpa@...or.com>,
"Thomas Gleixner (tglx@...utronix.de)" <tglx@...utronix.de>,
"'mingo@...e.hu' (mingo@...e.hu)" <mingo@...e.hu>,
"Borislav Petkov (bp@...en8.de)" <bp@...en8.de>,
Satoru Moriya <satoru.moriya@....com>,
"dle-develop@...ts.sourceforge.net"
<dle-develop@...ts.sourceforge.net>,
"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>
Subject: RE: [RFC][PATCH v6]trace,x86: add x86 irq vector tracepoints
Thank you for reviewing my patch.
I will update it in accordance with your comment.
Seiji
> -----Original Message-----
> From: Steven Rostedt [mailto:rostedt@...dmis.org]
> Sent: Monday, December 17, 2012 10:02 PM
> To: Seiji Aguchi
> Cc: x86@...nel.org; linux-kernel@...r.kernel.org; H. Peter Anvin (hpa@...or.com); Thomas Gleixner (tglx@...utronix.de);
> 'mingo@...e.hu' (mingo@...e.hu); Borislav Petkov (bp@...en8.de); Satoru Moriya; dle-develop@...ts.sourceforge.net; linux-
> edac@...r.kernel.org; Luck, Tony (tony.luck@...el.com)
> Subject: Re: [RFC][PATCH v6]trace,x86: add x86 irq vector tracepoints
>
> On Tue, 2012-12-18 at 01:34 +0000, Seiji Aguchi wrote:
> > Change log
> >
> > v5 -> v6
> > - Rebased to 3.7
> >
> > v4 -> v5
> > - Rebased to 3.6.0
> >
> > - Introduce a logic switching IDT at enabling/disabling TP time
> > so that a time penalty makes a zero when tracepoints are disabled.
> > This IDT is created only when CONFIG_TRACEPOINTS is enabled.
> >
> > - Remove arch_irq_vector_entry/exit and add followings again
> > so that we can add each tracepoint in a generic way.
> > - error_apic_vector
> > - thermal_apic_vector
> > - threshold_apic_vector
> > - spurious_apic_vector
> > - x86_platform_ipi_vector
> >
> > - Drop nmi tracepoints to begin with apic interrupts and discuss a logic switching
> > IDT first.
> >
> > - Move irq_vectors.h in the directory of arch/x86/include/asm/trace because
> > I'm not sure if a logic switching IDT is sharable with other architectures.
> >
> > v3 -> v4
> > - Add a latency measurement of each tracepoint
> > - Rebased to 3.6-rc6
> >
> > v2 -> v3
> > - Remove an invalidate_tlb_vector event because it was replaced by a call function vector
> > in a following commit.
> >
> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;
> > h=52aec3308db85f4e9f5c8b9f5dc4fbd0138c6fa4
> >
> > v1 -> v2
> > - Modify variable name from irq to vector.
> > - Merge arch-specific tracepoints below to an arch_irq_vector_entry/exit.
> > - error_apic_vector
> > - thermal_apic_vector
> > - threshold_apic_vector
> > - spurious_apic_vector
> > - x86_platform_ipi_vector
> >
> > [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.
> >
> > This patch adds 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, it introduces a logic switching IDT at enabling/disabling time
> > so that a time penalty makes a complete zero when tracepoints are disabled. Detailed explanations are as follows.
> > - Create new irq handlers inserted tracepoints by using macros.
> > - Create a new IDT, trace_idt_table, at boot time by duplicating original IDT, idt table, and
> > registering the new handers for tracpoints.
> > - Switch IDT to new one at enabling TP time.
> > - Restore to an original IDT at disabling TP time.
> > The new IDT is created only when CONFIG_TRACEPOINTS is enabled to avoid being used for other purposes.
> >
> > Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
> > ---
> > arch/x86/include/asm/desc.h | 27 +++++
> > arch/x86/include/asm/entry_arch.h | 32 +++++
> > arch/x86/include/asm/hw_irq.h | 14 +++
> > arch/x86/kernel/Makefile | 1 +
> > arch/x86/kernel/apic/apic.c | 186 +++++++++++++++++-------------
> > arch/x86/kernel/cpu/mcheck/therm_throt.c | 26 +++--
> > arch/x86/kernel/cpu/mcheck/threshold.c | 27 +++--
> > arch/x86/kernel/entry_64.S | 33 ++++++
> > arch/x86/kernel/head_64.S | 6 +
> > arch/x86/kernel/irq.c | 44 ++++---
> > arch/x86/kernel/irq_work.c | 22 +++-
> > arch/x86/kernel/irqinit.c | 2 +
> > arch/x86/kernel/smp.c | 68 ++++++++----
> > 13 files changed, 345 insertions(+), 143 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
> > index 8bf1c06..52becf4 100644
> > --- a/arch/x86/include/asm/desc.h
> > +++ b/arch/x86/include/asm/desc.h
> > @@ -345,6 +345,33 @@ static inline void set_intr_gate(unsigned int n, void *addr)
> > _set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS); }
> >
> > +#ifdef CONFIG_TRACEPOINTS
> > +extern gate_desc trace_idt_table[];
> > +extern void trace_idt_table_init(void); static inline void
> > +_trace_set_gate(int gate, unsigned type, void *addr,
> > + unsigned dpl, unsigned ist, unsigned seg) {
> > + gate_desc s;
> > +
> > + pack_gate(&s, type, (unsigned long)addr, dpl, ist, seg);
> > + /*
> > + * does not need to be atomic because it is only done once at
> > + * setup time
> > + */
> > + write_idt_entry(trace_idt_table, gate, &s); }
> > +
> > +static inline void trace_set_intr_gate(unsigned int n, void *addr) {
> > + BUG_ON((unsigned)n > 0xFF);
> > + _trace_set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS); } #else
> > +static inline void trace_idt_table_init(void) { } #endif
> > +
> > extern int first_system_vector;
> > /* used_vectors is BITMAP for irq is not managed by percpu vector_irq
> > */ extern unsigned long used_vectors[]; diff --git
> > a/arch/x86/include/asm/entry_arch.h
> > b/arch/x86/include/asm/entry_arch.h
> > index 40afa00..8ef3900 100644
> > --- a/arch/x86/include/asm/entry_arch.h
> > +++ b/arch/x86/include/asm/entry_arch.h
> > @@ -45,3 +45,35 @@
> > BUILD_INTERRUPT(threshold_interrupt,THRESHOLD_APIC_VECTOR)
> > #endif
> >
> > #endif
> > +
> > +#ifdef CONFIG_TRACEPOINTS
> > +#ifdef CONFIG_SMP
> > +BUILD_INTERRUPT(trace_reschedule_interrupt, RESCHEDULE_VECTOR)
> > +BUILD_INTERRUPT(trace_call_function_interrupt, CALL_FUNCTION_VECTOR)
> > +BUILD_INTERRUPT(trace_call_function_single_interrupt,
> > + CALL_FUNCTION_SINGLE_VECTOR)
> > +#endif
> > +
> > +BUILD_INTERRUPT(trace_x86_platform_ipi, X86_PLATFORM_IPI_VECTOR)
> > +
> > +#ifdef CONFIG_X86_LOCAL_APIC
> > +
> > +BUILD_INTERRUPT(trace_apic_timer_interrupt, LOCAL_TIMER_VECTOR)
> > +BUILD_INTERRUPT(trace_error_interrupt, ERROR_APIC_VECTOR)
> > +BUILD_INTERRUPT(trace_spurious_interrupt, SPURIOUS_APIC_VECTOR)
> > +
> > +#ifdef CONFIG_IRQ_WORK
> > +BUILD_INTERRUPT(trace_irq_work_interrupt, IRQ_WORK_VECTOR) #endif
> > +
> > +#ifdef CONFIG_X86_THERMAL_VECTOR
> > +BUILD_INTERRUPT(trace_thermal_interrupt, THERMAL_APIC_VECTOR) #endif
> > +
> > +#ifdef CONFIG_X86_MCE_THRESHOLD
> > +BUILD_INTERRUPT(trace_threshold_interrupt, THRESHOLD_APIC_VECTOR)
> > +#endif
> > +
> > +#endif
>
> Um, you could save all the above duplication if you just did:
>
> in arch/x86/kernel/entry_32.S
>
> #ifdef CONFIG_TRACING
> #define BUILD_TRACE_INTERRUPT(name, nr) \
> BUILD_INTERRUPT3(trace_##name, nr, smp_trace_##name) #else #define BUILD_TRACE_INTERRUPT(name, nr) #endif
>
> #define BUILD_INTERRUPT(name, nr) \
> BUILD_INTERRUPT3(name, nr, smp_##name) \
> BUILD_TRACE_INTERRUPT(name, nr)
>
> #include <asm/entry_arch.h>
>
>
> > +
> > +#endif /* CONFIG_TRACEPOINTS */
> > diff --git a/arch/x86/include/asm/hw_irq.h
> > b/arch/x86/include/asm/hw_irq.h index eb92a6e..4472a78 100644
> > --- a/arch/x86/include/asm/hw_irq.h
> > +++ b/arch/x86/include/asm/hw_irq.h
> > @@ -76,6 +76,20 @@ extern void threshold_interrupt(void); extern void
> > call_function_interrupt(void); extern void
> > call_function_single_interrupt(void);
> >
> > +#ifdef CONFIG_TRACEPOINTS
> > +/* Interrupt handlers registered during init_IRQ */ extern void
> > +trace_apic_timer_interrupt(void);
> > +extern void trace_x86_platform_ipi(void); extern void
> > +trace_error_interrupt(void); extern void
> > +trace_irq_work_interrupt(void); extern void
> > +trace_spurious_interrupt(void); extern void
> > +trace_thermal_interrupt(void); extern void
> > +trace_reschedule_interrupt(void);
> > +extern void trace_threshold_interrupt(void); extern void
> > +trace_call_function_interrupt(void);
> > +extern void trace_call_function_single_interrupt(void);
> > +#endif /* CONFIG_TRACEPOINTS */
> > +
> > /* IOAPIC */
> > #define IO_APIC_IRQ(x) (((x) >= NR_IRQS_LEGACY) || ((1<<(x)) &
> > io_apic_irqs)) extern unsigned long io_apic_irqs; diff --git
> > a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index
> > 34e923a..33504ea 100644
> > --- a/arch/x86/kernel/Makefile
> > +++ b/arch/x86/kernel/Makefile
> > @@ -100,6 +100,7 @@ obj-$(CONFIG_OF) += devicetree.o
> > obj-$(CONFIG_UPROBES) += uprobes.o
> >
> > obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
> > +obj-$(CONFIG_TRACEPOINTS) += tracepoint.o
> >
> > ###
> > # 64 bit specific files
> > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> > index b994cc8..20c4b1f 100644
> > --- a/arch/x86/kernel/apic/apic.c
> > +++ b/arch/x86/kernel/apic/apic.c
> > @@ -55,6 +55,9 @@
> > #include <asm/tsc.h>
> > #include <asm/hypervisor.h>
> >
> > +#define CREATE_TRACE_POINTS
> > +#include <asm/trace/irq_vectors.h>
> > +
> > unsigned int num_processors;
> >
> > unsigned disabled_cpus __cpuinitdata; @@ -912,27 +915,34 @@ static
> > void local_apic_timer_interrupt(void)
> > * [ if a single-CPU system runs an SMP kernel then we call the local
> > * interrupt as well. Thus we cannot inline the local irq ... ]
> > */
> > -void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs) -{
> > - struct pt_regs *old_regs = set_irq_regs(regs);
> > -
> > - /*
> > - * NOTE! We'd better ACK the irq immediately,
> > - * because timer handling can be slow.
> > - */
> > - ack_APIC_irq();
> > - /*
> > - * update_process_times() expects us to have done irq_enter().
> > - * Besides, if we don't timer interrupts ignore the global
> > - * interrupt lock, which is the WrongThing (tm) to do.
> > - */
> > - irq_enter();
> > - exit_idle();
> > - local_apic_timer_interrupt();
> > - irq_exit();
> > -
> > - set_irq_regs(old_regs);
> > -}
> > +#define SMP_APIC_TIMER_INTERRUPT(trace, trace_enter, trace_exit) \
> > +void __irq_entry smp_##trace##apic_timer_interrupt(struct pt_regs *regs)\
> > +{ \
> > + struct pt_regs *old_regs = set_irq_regs(regs); \
> > + \
> > + /* \
> > + * NOTE! We'd better ACK the irq immediately, \
> > + * because timer handling can be slow. \
> > + */ \
> > + ack_APIC_irq(); \
> > + /* \
> > + * update_process_times() expects us to have done irq_enter(). \
> > + * Besides, if we don't timer interrupts ignore the global \
> > + * interrupt lock, which is the WrongThing (tm) to do. \
> > + */ \
> > + irq_enter(); \
> > + exit_idle(); \
> > + trace_enter; \
> > + local_apic_timer_interrupt(); \
> > + trace_exit; \
> > + irq_exit(); \
> > + \
> > + set_irq_regs(old_regs); \
> > +}
> > +
> > +SMP_APIC_TIMER_INTERRUPT(,,)
> > +SMP_APIC_TIMER_INTERRUPT(trace_, trace_local_timer_entry(LOCAL_TIMER_VECTOR),
> > + trace_local_timer_exit(LOCAL_TIMER_VECTOR))
>
>
> These macros are just plan ugly as all hell. What about using static inlines and something like:
>
> static inline void entering_irq(void)
> {
> irq_enter();
> exit_idle();
> }
>
> static inline void exiting_irq(void)
> {
> irq_exit();
> }
>
> -- Just duplicate the two apic timer interrupts because it has the needed ack first.
>
>
> Then the rest could be:
>
> static inline void __smp_spurious_interrupt(struct pt_regs *regs) {
> u32 v;
>
>
> /*
> * Check if this really is a spurious interrupt and ACK it
> * if it is a vectored one. Just in case...
> * Spurious interrupts should not be ACKed.
> */
> v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));
> if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))
> ack_APIC_irq();
>
> inc_irq_stat(irq_spurious_count);
>
> /* see sw-dev-man vol 3, chapter 7.4.13.5 */
> pr_info("spurious APIC interrupt on CPU#%d, "
> "should never happen.\n", smp_processor_id());
>
> }
>
> void smp_spurious_interrupt(struct pt_regs *regs) {
> entering_irq();
> __smp_spurious_interrupt(regs);
> exiting_irq();
> }
>
> void smp_trace_spurious_interrupt(struct pt_regs *regs) {
> entering_irq();
> trace_spurious_apic_enter(SPURIOUS_APIC_VECTOR);
> __smp_spurious_interrupt(regs);
> trace_spurious_apic_exit(SPURIOUS_APIC_VECTOR);
> exiting_irq();
> }
>
> This is so much more readable (and maintainable) than using those ugly macros.
>
> -- Steve
>
> >
> > int setup_profiling_timer(unsigned int multiplier) { @@ -1908,71
> > +1918,91 @@ int __init APIC_init_uniprocessor(void)
> > /*
> > * This interrupt should _never_ happen with our APIC/SMP architecture
> > */
> > -void smp_spurious_interrupt(struct pt_regs *regs) -{
> > - u32 v;
> > -
> > - irq_enter();
> > - exit_idle();
> > - /*
> > - * Check if this really is a spurious interrupt and ACK it
> > - * if it is a vectored one. Just in case...
> > - * Spurious interrupts should not be ACKed.
> > - */
> > - v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));
> > - if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))
> > - ack_APIC_irq();
> > -
> > - inc_irq_stat(irq_spurious_count);
> > -
> > - /* see sw-dev-man vol 3, chapter 7.4.13.5 */
> > - pr_info("spurious APIC interrupt on CPU#%d, "
> > - "should never happen.\n", smp_processor_id());
> > - irq_exit();
> > -}
> > +#define SMP_SPURIOUS_INTERRUPT(trace, trace_enter, trace_exit) \
> > +void smp_##trace##spurious_interrupt(struct pt_regs *regs) \
> > +{ \
> > + u32 v; \
> > + \
> > + irq_enter(); \
> > + exit_idle(); \
> > + trace_enter; \
> > + /* \
> > + * Check if this really is a spurious interrupt and ACK it \
> > + * if it is a vectored one. Just in case... \
> > + * Spurious interrupts should not be ACKed. \
> > + */ \
> > + v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));\
> > + if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f))) \
> > + ack_APIC_irq(); \
> > + \
> > + inc_irq_stat(irq_spurious_count); \
> > + \
> > + /* see sw-dev-man vol 3, chapter 7.4.13.5 */ \
> > + pr_info("spurious APIC interrupt on CPU#%d, " \
> > + "should never happen.\n", smp_processor_id()); \
> > + trace_exit; \
> > + irq_exit(); \
> > +}
> > +
> > +SMP_SPURIOUS_INTERRUPT(,,)
> > +SMP_SPURIOUS_INTERRUPT(trace_, trace_spurious_apic_entry(SPURIOUS_APIC_VECTOR),
> > + trace_spurious_apic_exit(SPURIOUS_APIC_VECTOR))
> >
> > /*
> > * This interrupt should never happen with our APIC/SMP architecture
> > */
> > -void smp_error_interrupt(struct pt_regs *regs) -{
> > - u32 v0, v1;
> > - u32 i = 0;
> > - static const char * const error_interrupt_reason[] = {
> > - "Send CS error", /* APIC Error Bit 0 */
> > - "Receive CS error", /* APIC Error Bit 1 */
> > - "Send accept error", /* APIC Error Bit 2 */
> > - "Receive accept error", /* APIC Error Bit 3 */
> > - "Redirectable IPI", /* APIC Error Bit 4 */
> > - "Send illegal vector", /* APIC Error Bit 5 */
> > - "Received illegal vector", /* APIC Error Bit 6 */
> > - "Illegal register address", /* APIC Error Bit 7 */
> > - };
> > -
> > - irq_enter();
> > - exit_idle();
> > - /* First tickle the hardware, only then report what went on. -- REW */
> > - v0 = apic_read(APIC_ESR);
> > - apic_write(APIC_ESR, 0);
> > - v1 = apic_read(APIC_ESR);
> > - ack_APIC_irq();
> > - atomic_inc(&irq_err_count);
> > -
> > - apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x(%02x)",
> > - smp_processor_id(), v0 , v1);
> > -
> > - v1 = v1 & 0xff;
> > - while (v1) {
> > - if (v1 & 0x1)
> > - apic_printk(APIC_DEBUG, KERN_CONT " : %s", error_interrupt_reason[i]);
> > - i++;
> > - v1 >>= 1;
> > - }
> > -
> > - apic_printk(APIC_DEBUG, KERN_CONT "\n");
> > -
> > - irq_exit();
> > -}
>
--
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