From d17d8f9dedb9dd76fd540a5c497101529d9eb25a Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Thu, 31 Jul 2014 08:40:59 -0700 Subject: [PATCH] x86/mm: Add tracepoints for TLB flushes We don't have any good way to figure out what kinds of flushes are being attempted. Right now, we can try to use the vm counters, but those only tell us what we actually did with the hardware (one-by-one vs full) and don't tell us what was actually _requested_. This allows us to select out "interesting" TLB flushes that we might want to optimize (like the ranged ones) and ignore the ones that we have very little control over (the ones at context switch). Signed-off-by: Dave Hansen Link: http://lkml.kernel.org/r/20140731154059.4C96CBA5@viggo.jf.intel.com Acked-by: Rik van Riel Cc: Mel Gorman Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/mmu_context.h | 6 ++++++ arch/x86/mm/init.c | 7 +++++++ arch/x86/mm/tlb.c | 11 +++++++++-- include/linux/mm_types.h | 8 ++++++++ include/trace/events/tlb.h | 40 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 70 insertions(+), 2 deletions(-) create mode 100644 include/trace/events/tlb.h diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index be12c53..166af2a 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -3,6 +3,10 @@ #include #include +#include + +#include + #include #include #include @@ -44,6 +48,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, /* Re-load page tables */ load_cr3(next->pgd); + trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL); /* Stop flush ipis for the previous mm */ cpumask_clear_cpu(cpu, mm_cpumask(prev)); @@ -71,6 +76,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, * to make sure to use no freed page tables. */ load_cr3(next->pgd); + trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL); load_LDT_nolock(&next->context); } } diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index f971306..66dba36 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -18,6 +18,13 @@ #include /* for MAX_DMA_PFN */ #include +/* + * We need to define the tracepoints somewhere, and tlb.c + * is only compied when SMP=y. + */ +#define CREATE_TRACE_POINTS +#include + #include "mm_internal.h" static unsigned long __initdata pgt_buf_start; diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index add5a0f..6f00ecb 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -49,6 +49,7 @@ void leave_mm(int cpu) if (cpumask_test_cpu(cpu, mm_cpumask(active_mm))) { cpumask_clear_cpu(cpu, mm_cpumask(active_mm)); load_cr3(swapper_pg_dir); + trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL); } } EXPORT_SYMBOL_GPL(leave_mm); @@ -107,15 +108,19 @@ static void flush_tlb_func(void *info) count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED); if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK) { - if (f->flush_end == TLB_FLUSH_ALL) + if (f->flush_end == TLB_FLUSH_ALL) { local_flush_tlb(); - else { + trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, TLB_FLUSH_ALL); + } else { unsigned long addr; + unsigned long nr_pages = + f->flush_end - f->flush_start / PAGE_SIZE; addr = f->flush_start; while (addr < f->flush_end) { __flush_tlb_single(addr); addr += PAGE_SIZE; } + trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, nr_pages); } } else leave_mm(smp_processor_id()); @@ -153,6 +158,7 @@ void flush_tlb_current_task(void) count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL); local_flush_tlb(); + trace_tlb_flush(TLB_LOCAL_SHOOTDOWN, TLB_FLUSH_ALL); if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids) flush_tlb_others(mm_cpumask(mm), mm, 0UL, TLB_FLUSH_ALL); preempt_enable(); @@ -191,6 +197,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, __flush_tlb_single(addr); } } + trace_tlb_flush(TLB_LOCAL_MM_SHOOTDOWN, base_pages_to_flush); out: if (base_pages_to_flush == TLB_FLUSH_ALL) { start = 0UL; diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 96c5750..796deac 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -516,4 +516,12 @@ struct vm_special_mapping struct page **pages; }; +enum tlb_flush_reason { + TLB_FLUSH_ON_TASK_SWITCH, + TLB_REMOTE_SHOOTDOWN, + TLB_LOCAL_SHOOTDOWN, + TLB_LOCAL_MM_SHOOTDOWN, + NR_TLB_FLUSH_REASONS, +}; + #endif /* _LINUX_MM_TYPES_H */ diff --git a/include/trace/events/tlb.h b/include/trace/events/tlb.h new file mode 100644 index 0000000..13391d2 --- /dev/null +++ b/include/trace/events/tlb.h @@ -0,0 +1,40 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM tlb + +#if !defined(_TRACE_TLB_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_TLB_H + +#include +#include + +#define TLB_FLUSH_REASON \ + { TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" }, \ + { TLB_REMOTE_SHOOTDOWN, "remote shootdown" }, \ + { TLB_LOCAL_SHOOTDOWN, "local shootdown" }, \ + { TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" } + +TRACE_EVENT(tlb_flush, + + TP_PROTO(int reason, unsigned long pages), + TP_ARGS(reason, pages), + + TP_STRUCT__entry( + __field( int, reason) + __field(unsigned long, pages) + ), + + TP_fast_assign( + __entry->reason = reason; + __entry->pages = pages; + ), + + TP_printk("pages:%ld reason:%s (%d)", + __entry->pages, + __print_symbolic(__entry->reason, TLB_FLUSH_REASON), + __entry->reason) +); + +#endif /* _TRACE_TLB_H */ + +/* This part must be outside protection */ +#include -- 2.7.4