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x86/mm: Add tracepoints for TLB flushes

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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 <dave.hansen@linux.intel.com>
Link: http://lkml.kernel.org/r/20140731154059.4C96CBA5@viggo.jf.intel.com
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Dave Hansen 2014-07-31 08:40:59 -07:00 committed by H. Peter Anvin
parent a23421f111
commit d17d8f9ded
5 changed files with 70 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/mmu_context.h
View File

@ -3,6 +3,10 @@
#include <asm/desc.h>
#include <linux/atomic.h>
#include <linux/mm_types.h>
#include <trace/events/tlb.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
@ -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);
}
}

7
arch/x86/mm/init.c
View File

@ -18,6 +18,13 @@
#include <asm/dma.h> /* for MAX_DMA_PFN */
#include <asm/microcode.h>
/*
* We need to define the tracepoints somewhere, and tlb.c
* is only compied when SMP=y.
*/
#define CREATE_TRACE_POINTS
#include <trace/events/tlb.h>
#include "mm_internal.h"
static unsigned long __initdata pgt_buf_start;

11
arch/x86/mm/tlb.c
View File

@ -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;

8
include/linux/mm_types.h
View File

@ -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 */

40
include/trace/events/tlb.h Normal file
View File

@ -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 <linux/mm_types.h>
#include <linux/tracepoint.h>
#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 <trace/define_trace.h>