[PATCH] mm: cma: add trace events for CMA allocations and freeings

[PATCH] mm: cma: add trace events for CMA allocations and freeings

[Stefan Strogin]

Add trace events for cma_alloc() and cma_release().

The cma_alloc tracepoint is used both for successful and failed allocations,
in case of allocation failure pfn=-1UL is stored and printed.

Signed-off-by: Stefan Strogin <stefan.strogin@gmail.com>
---

Took out from the patch set "mm: cma: add some debug information for CMA" v4
(http://thread.gmane.org/gmane.linux.kernel.mm/129903) because of probable
uselessness of the rest of the patches.

Changes from the version from the patch set:
- Constify the struct page * parameter passed to the tracepoints.
- Pass both pfn and struct page * to the tracepoints to decrease unnecessary
  pfn_to_page() and page_to_pfn() calls and avoid using them in TP_printk.
- Store and print pfn=-1UL instead of pfn=0, because 0th pfn can truly exist
  on some architectures.

 include/trace/events/cma.h | 63 ++++++++++++++++++++++++++++++++++++++++++++++
 mm/cma.c                   |  5 ++++
 2 files changed, 68 insertions(+)
 create mode 100644 include/trace/events/cma.h

diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h
new file mode 100644
index 0000000..e01b35d
--- /dev/null
+++ b/include/trace/events/cma.h
@@ -0,0 +1,63 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM cma
+
+#if !defined(_TRACE_CMA_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_CMA_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(cma_alloc,
+
+	TP_PROTO(unsigned long pfn, const struct page *page,
+		 unsigned int count),
+
+	TP_ARGS(pfn, page, count),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, pfn)
+		__field(const struct page *, page)
+		__field(unsigned int, count)
+	),
+
+	TP_fast_assign(
+		__entry->pfn = pfn;
+		__entry->page = page;
+		__entry->count = count;
+	),
+
+	TP_printk("pfn=%lx page=%p count=%u",
+		  __entry->pfn,
+		  __entry->page,
+		  __entry->count)
+);
+
+TRACE_EVENT(cma_release,
+
+	TP_PROTO(unsigned long pfn, const struct page *page,
+		 unsigned int count),
+
+	TP_ARGS(pfn, page, count),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, pfn)
+		__field(const struct page *, page)
+		__field(unsigned int, count)
+	),
+
+	TP_fast_assign(
+		__entry->pfn = pfn;
+		__entry->page = page;
+		__entry->count = count;
+	),
+
+	TP_printk("pfn=%lx page=%p count=%u",
+		  __entry->pfn,
+		  __entry->page,
+		  __entry->count)
+);
+
+#endif /* _TRACE_CMA_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/mm/cma.c b/mm/cma.c
index 47203fa..e9410b7c 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -23,6 +23,7 @@
 #  define DEBUG
 #endif
 #endif
+#define CREATE_TRACE_POINTS
 
 #include <linux/memblock.h>
 #include <linux/err.h>
@@ -34,6 +35,7 @@
 #include <linux/cma.h>
 #include <linux/highmem.h>
 #include <linux/io.h>
+#include <trace/events/cma.h>
 
 #include "cma.h"
 
@@ -414,6 +416,8 @@ struct page *cma_alloc(struct cma *cma, unsigned int count, unsigned int align)
 		start = bitmap_no + mask + 1;
 	}
 
+	trace_cma_alloc(page ? pfn : -1UL, page, count);
+
 	pr_debug("%s(): returned %p\n", __func__, page);
 	return page;
 }
@@ -446,6 +450,7 @@ bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
 
 	free_contig_range(pfn, count);
 	cma_clear_bitmap(cma, pfn, count);
+	trace_cma_release(pfn, pages, count);
 
 	return true;
 }
-- 
2.1.0

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Re: [PATCH] mm: cma: add trace events for CMA allocations and freeings

[Joonsoo Kim]

Hello,

On Wed, Apr 01, 2015 at 04:31:43PM +0300, Stefan Strogin wrote:
> Add trace events for cma_alloc() and cma_release().
> 
> The cma_alloc tracepoint is used both for successful and failed allocations,
> in case of allocation failure pfn=-1UL is stored and printed.
> 
> Signed-off-by: Stefan Strogin <stefan.strogin@gmail.com>
> ---
> 
> Took out from the patch set "mm: cma: add some debug information for CMA" v4
> (http://thread.gmane.org/gmane.linux.kernel.mm/129903) because of probable
> uselessness of the rest of the patches.

I think that patch 5/5 in previous submission is handy and
simple to merge. Although we can calculate it by using bitmap,
it would be good to get that information(used size and maxchunk size)
directly.


> @@ -414,6 +416,8 @@ struct page *cma_alloc(struct cma *cma, unsigned int count, unsigned int align)
>  		start = bitmap_no + mask + 1;
>  	}
>  
> +	trace_cma_alloc(page ? pfn : -1UL, page, count);
> +

I think that tracing align is also useful.
Is there any reason not to include it?

Thanks.

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Re: [PATCH] mm: cma: add trace events for CMA allocations and freeings

[Stefan Strogin]

Hello Joonsoo,

On 02/04/15 10:33, Joonsoo Kim wrote:
> Hello,
> 
> On Wed, Apr 01, 2015 at 04:31:43PM +0300, Stefan Strogin wrote:
>> Add trace events for cma_alloc() and cma_release().
>>
>> The cma_alloc tracepoint is used both for successful and failed allocations,
>> in case of allocation failure pfn=-1UL is stored and printed.
>>
>> Signed-off-by: Stefan Strogin <stefan.strogin@gmail.com>
>> ---
>>
>> Took out from the patch set "mm: cma: add some debug information for CMA" v4
>> (http://thread.gmane.org/gmane.linux.kernel.mm/129903) because of probable
>> uselessness of the rest of the patches.
> 
> I think that patch 5/5 in previous submission is handy and
> simple to merge. Although we can calculate it by using bitmap,
> it would be good to get that information(used size and maxchunk size)
> directly.

Well, then I can send the patch 5/5 once more, this time singly.

> 
>> @@ -414,6 +416,8 @@ struct page *cma_alloc(struct cma *cma, unsigned int count, unsigned int align)
>>  		start = bitmap_no + mask + 1;
>>  	}
>>  
>> +	trace_cma_alloc(page ? pfn : -1UL, page, count);
>> +
> 
> I think that tracing align is also useful.
> Is there any reason not to include it?

In our case (DMA) alignment is easily calculated from the allocation
size and CONFIG_CMA_ALIGNMENT. But I think you're right, e.g. it may be
not so obvious on powerpc kvm? Anyway it won't be a shortcoming if we
trace 'align' too.

> 
> Thanks.

Thank you for the reply.

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[PATCH] mm-cma-add-trace-events-for-cma-allocations-and-freeings-fix

[Stefan Strogin]

Trace 'align' too in cma_alloc trace event.

Signed-off-by: Stefan Strogin <stefan.strogin@gmail.com>
---
 include/trace/events/cma.h | 11 +++++++----
 mm/cma.c                   |  2 +-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h
index e01b35d..d7cd961 100644
--- a/include/trace/events/cma.h
+++ b/include/trace/events/cma.h
@@ -10,26 +10,29 @@
 TRACE_EVENT(cma_alloc,
 
 	TP_PROTO(unsigned long pfn, const struct page *page,
-		 unsigned int count),
+		 unsigned int count, unsigned int align),
 
-	TP_ARGS(pfn, page, count),
+	TP_ARGS(pfn, page, count, align),
 
 	TP_STRUCT__entry(
 		__field(unsigned long, pfn)
 		__field(const struct page *, page)
 		__field(unsigned int, count)
+		__field(unsigned int, align)
 	),
 
 	TP_fast_assign(
 		__entry->pfn = pfn;
 		__entry->page = page;
 		__entry->count = count;
+		__entry->align = align;
 	),
 
-	TP_printk("pfn=%lx page=%p count=%u",
+	TP_printk("pfn=%lx page=%p count=%u align=%u",
 		  __entry->pfn,
 		  __entry->page,
-		  __entry->count)
+		  __entry->count,
+		  __entry->align)
 );
 
 TRACE_EVENT(cma_release,
diff --git a/mm/cma.c b/mm/cma.c
index e9410b7c..3a7a67b 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -416,7 +416,7 @@ struct page *cma_alloc(struct cma *cma, unsigned int count, unsigned int align)
 		start = bitmap_no + mask + 1;
 	}
 
-	trace_cma_alloc(page ? pfn : -1UL, page, count);
+	trace_cma_alloc(page ? pfn : -1UL, page, count, align);
 
 	pr_debug("%s(): returned %p\n", __func__, page);
 	return page;
-- 
2.1.0

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