problems in kdump kernel if 'maxcpus=1' not specified?

[Ken'ichi Ohmichi]

Hi Jay,

Jay Lan wrote:
>>> In case of jay, it looks creating bitmaps itself took a long time. 
>>>
>> Do you have data for this?  I've not seen it.
> 
> I just posted detailed data. My initial post gave the amount of time
> spent in create_dump_bitmap().
> 
> The processing rate of pfn inside create_dump_bitmap() is about
>    184500-pfn/sec  on memory map that does not contain data needs to
>                    be saved.
>    213700-pfn/sec  on memory map that contain data to be saved.
> 
> Here is some memory mappend from /proc/iomem:
> 16003000000-16033dfffff : System RAM
> 16033e00000-160f7ffffff : System RAM
> 16800000000-168f7ffffff : System RAM
> 
> We do not spent time in scanning pfn between 160f8000000 and
> 16800000000.

In Bernhard's mail:
> 6045b9f000-60f7ffdfff : System RAM
> 16000100000-160003fffff : System RAM
> 16003000000-16033dfffff : System RAM

I guess that makedumpfile spends time in scanning memory gap
between 0x60f7ffdfff and 0x16000100000 when creating 1st-bitmap.

I created the attached patch that makedumpfile does not scan
memory gap when creating 1st-bitmap. Could you please try it ?
This patch is for makedumpfile-1.2.6.


Thanks
Ken'ichi Ohmichi


diff -puN backup/v1.2.6/makedumpfile.c makedumpfile/makedumpfile.c
--- backup/v1.2.6/makedumpfile.c	2008-06-05 15:17:17.000000000 +0900
+++ makedumpfile/makedumpfile.c	2008-07-17 22:33:58.000000000 +0900
@@ -3987,8 +3987,10 @@ exclude_free_page()
 int
 create_1st_bitmap()
 {
+	int i;
 	char *buf = NULL;
-	unsigned long long pfn, paddr;
+	unsigned long long pfn, pfn_start, pfn_end, pfn_bitmap1;
+	struct pt_load_segment *pls;
 	off_t offset_page;
 	int ret = FALSE;
 
@@ -4021,13 +4023,17 @@ create_1st_bitmap()
 	/*
 	 * If page is on memory hole, set bit on the 1st-bitmap.
 	 */
-	for (pfn = 0, paddr = 0; pfn < info->max_mapnr;
-	    pfn++, paddr += info->page_size) {
-		if (is_in_segs(paddr))
+	for (i = pfn_bitmap1 = 0; i < info->num_load_memory; i++) {
+		pls = &info->pt_load_segments[i];
+		pfn_start = pls->phys_start / info->page_size;
+		pfn_end = pls->phys_end / info->page_size;
+		for (pfn = pfn_start; pfn < pfn_end; pfn++) {
 			set_bit_on_1st_bitmap(pfn);
-		else
-			pfn_memhole++;
+			pfn_bitmap1++;
+		}
 	}
+	pfn_memhole = info->max_mapnr - pfn_bitmap1;
+
 	if (!sync_1st_bitmap())
 		goto out;