[PATCH] makedumpfile: use non-cyclic when possible

[PATCH] makedumpfile: use non-cyclic when possible

[Cliff Wickman]

From: Cliff Wickman <cpw@sgi.com>

If there is plenty of memory use non-cyclic mode.

Diffed against makedumpfile-1.5.4
Signed-off-by: Cliff Wickman <cpw@sgi.com>
---
 makedumpfile.c |   26 ++++++++++++++++++++++++++

Index: makedumpfile-1.5.4/makedumpfile.c
===================================================================
--- makedumpfile-1.5.4.orig/makedumpfile.c
+++ makedumpfile-1.5.4/makedumpfile.c
@@ -7638,6 +7638,23 @@ writeout_multiple_dumpfiles(void)
 	return ret;
 }
 
+/*
+ * Plenty of memory to do a non-cyclic dump.
+ * Default to non-cyclic in this case.
+ */
+static int
+plenty_of_memory(void)
+{
+	unsigned long free_size;
+	unsigned long needed_size;
+
+	free_size = get_free_memory_size();
+	needed_size = (info->max_mapnr * 2) / BITPERBYTE;
+	if (free_size > (needed_size + (10*1024*1024)))
+		return 1;
+	return 0;
+}
+
 int
 create_dumpfile(void)
 {
@@ -7655,6 +7672,15 @@ create_dumpfile(void)
 
 	print_vtop();
 
+	if (plenty_of_memory()) {
+		if (info->flag_cyclic == TRUE)
+			MSG("Plenty of memory; using non-cyclic mode.\n");
+		info->flag_cyclic = FALSE;
+	} else {
+		if (info->flag_cyclic == TRUE)
+			MSG("Restricted memory; staying in cyclic mode.\n");
+	}
+
 	num_retry = 0;
 retry:
 	if (info->flag_refiltering) {

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Re: [PATCH] makedumpfile: use non-cyclic when possible

[HATAYAMA Daisuke]

(2013/08/29 7:08), Cliff Wickman wrote:
> From: Cliff Wickman <cpw@sgi.com>
> 
> If there is plenty of memory use non-cyclic mode.
> 

If there is enough memory to use, the number of cycle is 1.
Cyclic mode in 1-cycle is the same as non-cyclic mode in theory.
If slow, it's better to improve cyclic mode implementation.

To be honest, I think the current non-cyclic mode should be implemented as 1-cycle case. Then, makedumpfile can reduce amount of code at the same time.

-- 
Thanks.
HATAYAMA, Daisuke


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Re: [PATCH] makedumpfile: use non-cyclic when possible

[Atsushi Kumagai]

(2013/08/30 9:40), HATAYAMA Daisuke wrote:
> (2013/08/29 7:08), Cliff Wickman wrote:
>> From: Cliff Wickman <cpw@sgi.com>
>>
>> If there is plenty of memory use non-cyclic mode.
>>
> 
> If there is enough memory to use, the number of cycle is 1.
> Cyclic mode in 1-cycle is the same as non-cyclic mode in theory.
> If slow, it's better to improve cyclic mode implementation.
> 
> To be honest, I think the current non-cyclic mode should be implemented as 1-cycle case. 
> Then, makedumpfile can reduce amount of code at the same time. 

Yes, I hope to get rid of non-cyclic mode.
When v1.5.0 was released, I retained non-cyclic mode as just
workaround since cyclic mode has big performance issue.
However, we have done some improvement for cyclic mode and
we will continue it.

So please don't make the code depend on non-cyclic mode and
make efforts to get rid of it.


Thanks
Atsushi Kumagai

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