Messages in this thread Patch in this message | | | Subject | [RFC][PATCH] trace transparent huge page splits | From | Dave Hansen <> | Date | Mon, 31 Jan 2011 16:55:47 -0800 |
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When we see transparent huge pages being broken down, we generally have no idea of finding anything out about how it happened, or what it affected.
A simple static tracepoint like this should at least get us some minimal information like a stack trace, the virtual address, and the mm that it happened to.
I'm not sure if there is a better way to do this with any of the other tracing mechanisms, but this seems to work at least for me. Does anybody else have a better way? Is it worth merging this kind of stuff, or is it best left out of tree as a debugging patch?
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> ---
linux-2.6.git-dave/include/trace/events/huge_memory.h | 32 ++++++++++++++++++ linux-2.6.git-dave/mm/huge_memory.c | 5 ++ 2 files changed, 37 insertions(+)
diff -puN /dev/null include/trace/events/huge_memory.h --- /dev/null 2011-01-21 14:16:26.635488000 -0800 +++ linux-2.6.git-dave/include/trace/events/huge_memory.h 2011-01-31 16:42:37.607926454 -0800 @@ -0,0 +1,32 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM huge_memory + +#if !defined(_TRACE_HUGE_MEMORY_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_HUGE_MEMORY_H + +#include <linux/types.h> +#include <linux/tracepoint.h> + +TRACE_EVENT(mm_huge_memory_split, + + TP_PROTO(struct mm_struct *mm, unsigned long address), + + TP_ARGS(mm, address), + + TP_STRUCT__entry( + __field(struct mm_struct *, mm) + __field(unsigned long, address) + ), + + TP_fast_assign( + __entry->mm = mm; + __entry->address = address; + ), + + TP_printk("mm=%p address=%p", __entry->mm, (void *)__entry->address) +); + +#endif /* _TRACE_HUGE_MEMORY_H */ + +/* This part must be outside protection */ +#include <trace/define_trace.h> diff -puN include/linux/huge_mm.h~huge_mem_trace include/linux/huge_mm.h diff -puN mm/huge_memory.c~huge_mem_trace mm/huge_memory.c --- linux-2.6.git/mm/huge_memory.c~huge_mem_trace 2011-01-31 16:40:38.752014520 -0800 +++ linux-2.6.git-dave/mm/huge_memory.c 2011-01-31 16:41:15.671987202 -0800 @@ -21,6 +21,9 @@ #include <asm/pgalloc.h> #include "internal.h" +#define CREATE_TRACE_POINTS +#include <trace/events/huge_memory.h> + /* * By default transparent hugepage support is enabled for all mappings * and khugepaged scans all mappings. Defrag is only invoked by @@ -1254,6 +1257,8 @@ static int __split_huge_page_map(struct pgtable_t pgtable; unsigned long haddr; + trace_mm_huge_memory_split(vma->vm_mm, address); + spin_lock(&mm->page_table_lock); pmd = page_check_address_pmd(page, mm, address, PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); diff -puN mm/vmscan.c~huge_mem_trace mm/vmscan.c diff -puN mm/page_io.c~huge_mem_trace mm/page_io.c diff -puN block/blk-core.c~huge_mem_trace block/blk-core.c _
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