v4: * Adopted Steven's suggestion to use "unsigned int" for nr_pages to save space in ring buffer since it is unlikely to have more than 0xffffffff pages are touched by gup in one invoke * Remove unnecessray type cast
v3: * Adopted suggestion from Dave Hansen to move the gup header include to the last * Adopted comments from Steven: - Use DECLARE_EVENT_CLASS and DEFINE_EVENT - Just keep necessary TP_ARGS * Moved archtichture specific fall-backable fast version trace point after the do while loop since it may jump to the slow version. * Not implement recording return value since Steven plans to have it in generic tracing code
v2: * Adopted commetns from Steven - remove all reference to tsk->comm since it is unnecessary for non-sched trace points - reduce arguments for __get_user_pages trace point and update mm/gup.c accordingly * Added Ralf's acked-by for patch 4/7.
Some background about why I think this might be useful.
When I was profiling some hugetlb related program, I got page-faults event doubled when hugetlb is enabled. When I looked into the code, I found page-faults come from two places, do_page_fault and gup. So, I tried to figure out which play a role (or both) in my use case. But I can't find existing finer tracing event for sub page-faults in current mainline kernel.
So, I added the gup trace points support to have finer tracing events for page-faults. The below events are added:
__get_user_pages __get_user_pages_fast fixup_user_fault
Both __get_user_pages and fixup_user_fault call handle_mm_fault.
Just added trace points to raw version __get_user_pages since all variants will call it finally to do real work.
Although __get_user_pages_fast doesn't call handle_mm_fault, it might be useful to have it to distinguish between slow and fast version.
Yang Shi (7): trace/events: Add gup trace events mm/gup: add gup trace points x86: mm/gup: add gup trace points mips: mm/gup: add gup trace points s390: mm/gup: add gup trace points sh: mm/gup: add gup trace points sparc64: mm/gup: add gup trace points
arch/mips/mm/gup.c | 7 +++++++ arch/s390/mm/gup.c | 6 ++++++ arch/sh/mm/gup.c | 7 +++++++ arch/sparc/mm/gup.c | 7 +++++++ arch/x86/mm/gup.c | 7 +++++++ include/trace/events/gup.h | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ mm/gup.c | 8 ++++++++ 7 files changed, 105 insertions(+) create mode 100644 include/trace/events/gup.h
page-faults events record the invoke to handle_mm_fault, but the invoke may come from do_page_fault or gup. In some use cases, the finer event count mey be needed, so add trace events support for:
__get_user_pages __get_user_pages_fast fixup_user_fault
Signed-off-by: Yang Shi yang.shi@linaro.org --- include/trace/events/gup.h | 63 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 include/trace/events/gup.h
diff --git a/include/trace/events/gup.h b/include/trace/events/gup.h new file mode 100644 index 0000000..ac0e011 --- /dev/null +++ b/include/trace/events/gup.h @@ -0,0 +1,63 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM gup + +#if !defined(_TRACE_GUP_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_GUP_H + +#include <linux/types.h> +#include <linux/tracepoint.h> + +TRACE_EVENT(gup_fixup_user_fault, + + TP_PROTO(unsigned long address), + + TP_ARGS(address), + + TP_STRUCT__entry( + __field( unsigned long, address ) + ), + + TP_fast_assign( + __entry->address = address; + ), + + TP_printk("address=%lx", __entry->address) +); + +DECLARE_EVENT_CLASS(gup, + + TP_PROTO(unsigned long start, unsigned int nr_pages), + + TP_ARGS(start, nr_pages), + + TP_STRUCT__entry( + __field( unsigned long, start ) + __field( unsigned int, nr_pages ) + ), + + TP_fast_assign( + __entry->start = start; + __entry->nr_pages = nr_pages; + ), + + TP_printk("start=%lx nr_pages=%d", __entry->start, __entry->nr_pages) +); + +DEFINE_EVENT(gup, gup_get_user_pages, + + TP_PROTO(unsigned long start, unsigned int nr_pages), + + TP_ARGS(start, nr_pages) +); + +DEFINE_EVENT(gup, gup_get_user_pages_fast, + + TP_PROTO(unsigned long start, unsigned int nr_pages), + + TP_ARGS(start, nr_pages) +); + +#endif /* _TRACE_GUP_H */ + +/* This part must be outside protection */ +#include <trace/define_trace.h>
For slow version, just add trace point for raw __get_user_pages since all slow variants call it to do the real work finally.
Signed-off-by: Yang Shi yang.shi@linaro.org --- mm/gup.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/mm/gup.c b/mm/gup.c index deafa2c..00a3cff 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -18,6 +18,9 @@
#include "internal.h"
+#define CREATE_TRACE_POINTS +#include <trace/events/gup.h> + static struct page *no_page_table(struct vm_area_struct *vma, unsigned int flags) { @@ -462,6 +465,8 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, if (!nr_pages) return 0;
+ trace_gup_get_user_pages(start, nr_pages); + VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
/* @@ -599,6 +604,7 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, if (!(vm_flags & vma->vm_flags)) return -EFAULT;
+ trace_gup_fixup_user_fault(address); ret = handle_mm_fault(mm, vma, address, fault_flags); if (ret & VM_FAULT_ERROR) { if (ret & VM_FAULT_OOM) @@ -1340,6 +1346,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, start, len))) return 0;
+ trace_gup_get_user_pages_fast(start, nr_pages); + /* * Disable interrupts. We use the nested form as we can already have * interrupts disabled by get_futex_key.
Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: x86@kernel.org Signed-off-by: Yang Shi yang.shi@linaro.org --- arch/x86/mm/gup.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index ae9a37b..a96bcb7 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -12,6 +12,9 @@
#include <asm/pgtable.h>
+#define CREATE_TRACE_POINTS +#include <trace/events/gup.h>> + static inline pte_t gup_get_pte(pte_t *ptep) { #ifndef CONFIG_X86_PAE @@ -270,6 +273,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, (void __user *)start, len))) return 0;
+ trace_gup_get_user_pages_fast(start, nr_pages); + /* * XXX: batch / limit 'nr', to avoid large irq off latency * needs some instrumenting to determine the common sizes used by @@ -373,6 +378,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, } while (pgdp++, addr = next, addr != end); local_irq_enable();
+ trace_gup_get_user_pages_fast(start, nr_pages); + VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT); return nr;
On Wed, 9 Dec 2015 09:29:20 -0800 Yang Shi yang.shi@linaro.org wrote:
Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: x86@kernel.org Signed-off-by: Yang Shi yang.shi@linaro.org
arch/x86/mm/gup.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index ae9a37b..a96bcb7 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -12,6 +12,9 @@ #include <asm/pgtable.h> +#define CREATE_TRACE_POINTS +#include <trace/events/gup.h>>
First off, does the above even compile?
Second, you already created the tracepoints in mm/gup.c, why are you creating them here again? CREATE_TRACE_POINTS must be defined only once per events/.h file.
-- Steve
static inline pte_t gup_get_pte(pte_t *ptep) { #ifndef CONFIG_X86_PAE @@ -270,6 +273,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, (void __user *)start, len))) return 0;
- trace_gup_get_user_pages_fast(start, nr_pages);
- /*
- XXX: batch / limit 'nr', to avoid large irq off latency
- needs some instrumenting to determine the common sizes used by
@@ -373,6 +378,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, } while (pgdp++, addr = next, addr != end); local_irq_enable();
- trace_gup_get_user_pages_fast(start, nr_pages);
- VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT); return nr;
On 12/9/2015 1:07 PM, Steven Rostedt wrote:
On Wed, 9 Dec 2015 09:29:20 -0800 Yang Shi yang.shi@linaro.org wrote:
Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: x86@kernel.org Signed-off-by: Yang Shi yang.shi@linaro.org
arch/x86/mm/gup.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index ae9a37b..a96bcb7 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -12,6 +12,9 @@
#include <asm/pgtable.h>
+#define CREATE_TRACE_POINTS +#include <trace/events/gup.h>>
First off, does the above even compile?
Second, you already created the tracepoints in mm/gup.c, why are you creating them here again? CREATE_TRACE_POINTS must be defined only once per events/.h file.
Sorry for that. The typo was introduced by git amend without running test build. The multiple definition of trace points was not caught by my shaky test script.
Will fix them soon.
Thanks, Yang
-- Steve
- static inline pte_t gup_get_pte(pte_t *ptep) { #ifndef CONFIG_X86_PAE
@@ -270,6 +273,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, (void __user *)start, len))) return 0;
- trace_gup_get_user_pages_fast(start, nr_pages);
- /*
- XXX: batch / limit 'nr', to avoid large irq off latency
- needs some instrumenting to determine the common sizes used by
@@ -373,6 +378,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, } while (pgdp++, addr = next, addr != end); local_irq_enable();
- trace_gup_get_user_pages_fast(start, nr_pages);
- VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT); return nr;
Cc: linux-mips@linux-mips.org Acked-by: Ralf Baechle ralf@linux-mips.org Signed-off-by: Yang Shi yang.shi@linaro.org --- arch/mips/mm/gup.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c index 349995d..e0d8838 100644 --- a/arch/mips/mm/gup.c +++ b/arch/mips/mm/gup.c @@ -15,6 +15,9 @@ #include <asm/cpu-features.h> #include <asm/pgtable.h>
+#define CREATE_TRACE_POINTS +#include <trace/events/gup.h> + static inline pte_t gup_get_pte(pte_t *ptep) { #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32) @@ -211,6 +214,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, (void __user *)start, len))) return 0;
+ trace_gup_get_user_pages_fast(start, nr_pages); + /* * XXX: batch / limit 'nr', to avoid large irq off latency * needs some instrumenting to determine the common sizes used by @@ -291,6 +296,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, } while (pgdp++, addr = next, addr != end); local_irq_enable();
+ trace_gup_get_user_pages_fast(start, nr_pages); + VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT); return nr; slow:
Cc: Martin Schwidefsky schwidefsky@de.ibm.com Cc: Heiko Carstens heiko.carstens@de.ibm.com Cc: linux-s390@vger.kernel.org Signed-off-by: Yang Shi yang.shi@linaro.org --- arch/s390/mm/gup.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index 12bbf0e..0ff7e92 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -12,6 +12,9 @@ #include <linux/rwsem.h> #include <asm/pgtable.h>
+#define CREATE_TRACE_POINTS +#include <trace/events/gup.h> + /* * The performance critical leaf functions are made noinline otherwise gcc * inlines everything into a single function which results in too much @@ -188,6 +191,9 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, end = start + len; if ((end <= start) || (end > TASK_SIZE)) return 0; + + trace_gup_get_user_pages_fast(start, nr_pages); + /* * local_irq_save() doesn't prevent pagetable teardown, but does * prevent the pagetables from being freed on s390.
Cc: linux-sh@vger.kernel.org Signed-off-by: Yang Shi yang.shi@linaro.org --- arch/sh/mm/gup.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c index e7af6a6..fa72aac 100644 --- a/arch/sh/mm/gup.c +++ b/arch/sh/mm/gup.c @@ -14,6 +14,9 @@ #include <linux/highmem.h> #include <asm/pgtable.h>
+#define CREATE_TRACE_POINTS +#include <trace/events/gup.h> + static inline pte_t gup_get_pte(pte_t *ptep) { #ifndef CONFIG_X2TLB @@ -178,6 +181,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, (void __user *)start, len))) return 0;
+ trace_gup_get_user_pages_fast(start, nr_pages); + /* * This doesn't prevent pagetable teardown, but does prevent * the pagetables and pages from being freed. @@ -244,6 +249,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, } while (pgdp++, addr = next, addr != end); local_irq_enable();
+ trace_gup_get_user_pages_fast(start, nr_pages); + VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT); return nr;
Cc: "David S. Miller" davem@davemloft.net Cc: sparclinux@vger.kernel.org Signed-off-by: Yang Shi yang.shi@linaro.org --- arch/sparc/mm/gup.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c index 2e5c4fc..d9f573c 100644 --- a/arch/sparc/mm/gup.c +++ b/arch/sparc/mm/gup.c @@ -12,6 +12,9 @@ #include <linux/rwsem.h> #include <asm/pgtable.h>
+#define CREATE_TRACE_POINTS +#include <trace/events/gup.h> + /* * The performance critical leaf functions are made noinline otherwise gcc * inlines everything into a single function which results in too much @@ -174,6 +177,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, len = (unsigned long) nr_pages << PAGE_SHIFT; end = start + len;
+ trace_gup_get_user_pages_fast(start, nr_pages); + local_irq_save(flags); pgdp = pgd_offset(mm, addr); do { @@ -236,6 +241,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
local_irq_enable();
+ trace_gup_get_user_pages_fast(start, nr_pages); + VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT); return nr;
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