[PATCH v2 0/2] makedumpfile: write out a whole part of the 1st bitmap before entering cyclic process

[PATCH v2 0/2] makedumpfile: write out a whole part of the 1st bitmap before entering cyclic process

[HATAYAMA Daisuke]

This patch set changes the implementation so that a whole part of the
1st bitmap is written out before entering cyclic process. By this:

- we no longer need to keep buffer for the 1st bitmap during cyclic
  process, and

- it's possible for incomplete crash dump, for example, generated in
  case of ENOSPC, to avoid the case that we don't know where memory is
  present.

Note that this patch only deal with a conversion from ELF to
kdump-compressed format only, not from ELF to ELF.

ChangeLog

v1 => v2)

- Fix a bug of assigning wrong cyclic buffer size from free memory
  size.

---

HATAYAMA Daisuke (2):
      Use memset() to improve the 1st bitmap initialization performance
      Write out a whole part of the 1st bitmap before entering cyclic process


 makedumpfile.c |  268 ++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 241 insertions(+), 27 deletions(-)

-- 

Thanks.
HATAYAMA, Daisuke

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[PATCH v2 1/2] Use memset() to improve the 1st bitmap initialization performance

[HATAYAMA Daisuke]

Currently, 1st bitmap is initialized per bits. This is very slow, in
particular, on large memory system more than tera bytes. Instead, use
memset() to initialize bitmap quickly.

This helps next patch that changes the 1st bitmap creation to be done
at each cycle.

Here area a simple benchmark program that measures initialization time
for 384 MiB bitmap corresponding to 12 TiB memory.

On Xeon E7-4820 2.00GHz, output example is as follows:

$ ./bench
17.420970
0.340347

Also, the average result of 10 times excluding max and min are:

old: 17.453785 sec
new:  0.340808 sec

==
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>

enum {
        PAGE_SIZE = 4096,
        BITSPERBYTE = 8,
};

static inline double getdtime(void)
{
        struct timeval tv;
        gettimeofday(&tv, NULL);
        return (double)tv.tv_sec + (double)tv.tv_usec * 1.0e-6;
}

int main(int argc, char **argv)
{
        const unsigned long long mem_size = 12ULL << 40;
        const unsigned long long max_pfn = mem_size / PAGE_SIZE;
        const size_t bitmap_size = max_pfn / BITSPERBYTE;
        char *bitmap1 = calloc(bitmap_size, sizeof(char));
        char *bitmap2 = calloc(bitmap_size, sizeof(char));
        unsigned long long pfn;
        double t1, t2;

        t1 = getdtime();
        for (pfn = 0; pfn < max_pfn; ++pfn) {
                bitmap1[pfn >> 3] |= 1 << (pfn & 7);
        }
        t2 = getdtime();

        printf("%lf\n", t2 - t1);

        t1 = getdtime();
        memset(bitmap2, 0xff, bitmap_size);
        t2 = getdtime();

        printf("%lf\n", t2 - t1);

        return 0;
}
==

Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
---
 makedumpfile.c |   28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 428c53e..4b6c0ed 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -4317,6 +4317,8 @@ create_1st_bitmap_cyclic()
 	unsigned long long pfn, pfn_bitmap1;
 	unsigned long long phys_start, phys_end;
 	unsigned long long pfn_start, pfn_end;
+	unsigned long long pfn_start_roundup, pfn_end_round;
+	unsigned long pfn_start_byte, pfn_end_byte;
 
 	/*
 	 * At first, clear all the bits on the 1st-bitmap.
@@ -4329,10 +4331,30 @@ create_1st_bitmap_cyclic()
 	 */
 	pfn_bitmap1 = 0;
 	for (i = 0; get_pt_load(i, &phys_start, &phys_end, NULL, NULL); i++) {
-		pfn_start = paddr_to_pfn(phys_start);
-		pfn_end   = paddr_to_pfn(phys_end);
+		pfn_start = MAX(paddr_to_pfn(phys_start), info->cyclic_start_pfn);
+		pfn_end   = MIN(paddr_to_pfn(phys_end), info->cyclic_end_pfn);
 
-		for (pfn = pfn_start; pfn < pfn_end; pfn++) {
+		if (pfn_start >= pfn_end)
+			continue;
+
+		pfn_start_roundup = roundup(pfn_start, BITPERBYTE);
+		pfn_end_round = round(pfn_end, BITPERBYTE);
+
+		for (pfn = pfn_start; pfn < pfn_start_roundup; pfn++) {
+			if (set_bit_on_1st_bitmap(pfn))
+				pfn_bitmap1++;
+		}
+
+		pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >> 3;
+		pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
+
+		memset(info->partial_bitmap1 + pfn_start_byte,
+		       0xff,
+		       pfn_end_byte - pfn_start_byte);
+
+		pfn_bitmap1 += (pfn_end_byte - pfn_start_byte) * BITPERBYTE;
+
+		for (pfn = pfn_end_round; pfn < pfn_end; pfn++) {
 			if (set_bit_on_1st_bitmap(pfn))
 				pfn_bitmap1++;
 		}


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[PATCH v2 2/2] Write out a whole part of the 1st bitmap before entering cyclic process

[HATAYAMA Daisuke]

Currently, 1st bitmap is created during cyclic process, but the
information represented by the 1st bitmap, originally present memory,
is still available from ELF program header table, so:

- we don't need to keep the 1st bitmap even in cyclic process, and

- it's possible to avoid the case where for incomplete crash dump
  generated in failure case due to for example ENOSPC, we don't know
  where memory is present.

Supported is a conversion from ELF to kdump-compressed format only,
not from ELF to ELF.

Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
---
 makedumpfile.c |  240 ++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 216 insertions(+), 24 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 4b6c0ed..dafe83b 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -3052,10 +3052,23 @@ out:
 				MSG("The buffer size for the cyclic mode will ");
 				MSG("be truncated to %lld byte.\n", free_memory);
 				/*
-				 * bufsize_cyclic is used to allocate 1st and 2nd bitmap, 
-				 * so it should be truncated to the half of free_memory.
+				 * On conversion from ELF to ELF,
+				 * bufsize_cyclic is used to allocate
+				 * 1st and 2nd bitmap, so it should be
+				 * truncated to the half of
+				 * free_memory.
+				 *
+				 * On conversion from ELF to
+				 * kdump-compressed format, a whole
+				 * part of the 1st bitmap is created
+				 * first, so a whole part of
+				 * free_memory is used for the 2nd
+				 * bitmap.
 				 */
-				info->bufsize_cyclic = free_memory / 2;
+				if (info->flag_elf_dumpfile)
+					info->bufsize_cyclic = free_memory / 2;
+				else
+					info->bufsize_cyclic = free_memory;
 			}
 		}
 
@@ -3328,6 +3341,33 @@ clear_bit_on_2nd_bitmap_for_kernel(unsigned long long pfn)
 	return clear_bit_on_2nd_bitmap(pfn);
 }
 
+int
+set_bit_on_2nd_bitmap(unsigned long long pfn)
+{
+	if (info->flag_cyclic) {
+		return set_bitmap_cyclic(info->partial_bitmap2, pfn, 1);
+	} else {
+		return set_bitmap(info->bitmap2, pfn, 1);
+	}
+}
+
+int
+set_bit_on_2nd_bitmap_for_kernel(unsigned long long pfn)
+{
+	unsigned long long maddr;
+
+	if (is_xen_memory()) {
+		maddr = ptom_xen(pfn_to_paddr(pfn));
+		if (maddr == NOT_PADDR) {
+			ERRMSG("Can't convert a physical address(%llx) to machine address.\n",
+			    pfn_to_paddr(pfn));
+			return FALSE;
+		}
+		pfn = paddr_to_pfn(maddr);
+	}
+	return set_bit_on_2nd_bitmap(pfn);
+}
+
 static inline int
 is_in_segs(unsigned long long paddr)
 {
@@ -4418,6 +4458,53 @@ exclude_zero_pages(void)
 	return TRUE;
 }
 
+static int
+initialize_2nd_bitmap_cyclic(void)
+{
+	int i;
+	unsigned long long pfn;
+	unsigned long long phys_start, phys_end;
+	unsigned long long pfn_start, pfn_end;
+	unsigned long long pfn_start_roundup, pfn_end_round;
+	unsigned long pfn_start_byte, pfn_end_byte;
+
+	/*
+	 * At first, clear all the bits on the 2nd-bitmap.
+	 */
+	initialize_bitmap_cyclic(info->partial_bitmap2);
+
+	/*
+	 * If page is on memory hole, set bit on the 2nd-bitmap.
+	 */
+	for (i = 0; get_pt_load(i, &phys_start, &phys_end, NULL, NULL); i++) {
+		pfn_start = MAX(paddr_to_pfn(phys_start), info->cyclic_start_pfn);
+		pfn_end = MIN(paddr_to_pfn(phys_end), info->cyclic_end_pfn);
+
+		if (pfn_start >= pfn_end)
+			continue;
+
+		pfn_start_roundup = roundup(pfn_start, BITPERBYTE);
+		pfn_end_round = round(pfn_end, BITPERBYTE);
+
+		for (pfn = pfn_start; pfn < pfn_start_roundup; ++pfn)
+			if (!set_bit_on_2nd_bitmap_for_kernel(pfn))
+				return FALSE;
+
+		pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >> 3;
+		pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
+
+		memset(info->partial_bitmap2 + pfn_start_byte,
+		       0xff,
+		       pfn_end_byte - pfn_start_byte);
+
+		for (pfn = pfn_end_round; pfn < pfn_end; ++pfn)
+			if (!set_bit_on_2nd_bitmap_for_kernel(pfn))
+				return FALSE;
+	}
+
+	return TRUE;
+}
+
 int
 __exclude_unnecessary_pages(unsigned long mem_map,
     unsigned long long pfn_start, unsigned long long pfn_end)
@@ -4584,12 +4671,6 @@ exclude_unnecessary_pages(void)
 	return TRUE;
 }
 
-void
-copy_bitmap_cyclic(void)
-{
-	memcpy(info->partial_bitmap2, info->partial_bitmap1, info->bufsize_cyclic);
-}
-
 int
 exclude_unnecessary_pages_cyclic(void)
 {
@@ -4597,10 +4678,8 @@ exclude_unnecessary_pages_cyclic(void)
 	struct mem_map_data *mmd;
 	struct timeval tv_start;
 
-	/*
-	 * Copy 1st-bitmap to 2nd-bitmap.
-	 */
-	copy_bitmap_cyclic();
+	if (!initialize_2nd_bitmap_cyclic())
+		return FALSE;
 
 	if ((info->dump_level & DL_EXCLUDE_FREE) && !info->page_is_buddy)
 		if (!exclude_free_page())
@@ -4657,7 +4736,7 @@ update_cyclic_region(unsigned long long pfn)
 	if (info->cyclic_end_pfn > info->max_mapnr)
 		info->cyclic_end_pfn = info->max_mapnr;
 
-	if (!create_1st_bitmap_cyclic())
+	if (info->flag_elf_dumpfile && !create_1st_bitmap_cyclic())
 		return FALSE;
 
 	if (!exclude_unnecessary_pages_cyclic())
@@ -4841,19 +4920,71 @@ prepare_bitmap_buffer_cyclic(void)
 	return TRUE;
 }
 
+int
+prepare_bitmap1_buffer_cyclic(void)
+{
+	/*
+	 * Prepare partial bitmap buffers for cyclic processing.
+	 */
+	if ((info->partial_bitmap1 = (char *)malloc(info->bufsize_cyclic)) == NULL) {
+		ERRMSG("Can't allocate memory for the 1st bitmaps. %s\n",
+		       strerror(errno));
+		return FALSE;
+	}
+	initialize_bitmap_cyclic(info->partial_bitmap1);
+
+	return TRUE;
+}
+
+int
+prepare_bitmap2_buffer_cyclic(void)
+{
+	unsigned long tmp;
+
+	/*
+	 * Create 2 bitmaps (1st-bitmap & 2nd-bitmap) on block_size
+	 * boundary. The crash utility requires both of them to be
+	 * aligned to block_size boundary.
+	 */
+	tmp = divideup(divideup(info->max_mapnr, BITPERBYTE), info->page_size);
+	info->len_bitmap = tmp * info->page_size * 2;
+
+	/*
+	 * Prepare partial bitmap buffers for cyclic processing.
+	 */
+	if ((info->partial_bitmap2 = (char *)malloc(info->bufsize_cyclic)) == NULL) {
+		ERRMSG("Can't allocate memory for the 2nd bitmaps. %s\n",
+		       strerror(errno));
+		return FALSE;
+	}
+	initialize_bitmap_cyclic(info->partial_bitmap2);
+
+	return TRUE;
+}
+
 void
-free_bitmap_buffer(void)
+free_bitmap1_buffer(void)
 {
 	if (info->bitmap1) {
 		free(info->bitmap1);
 		info->bitmap1 = NULL;
 	}
+}
+
+void
+free_bitmap2_buffer(void)
+{
 	if (info->bitmap2) {
 		free(info->bitmap2);
 		info->bitmap2 = NULL;
 	}
+}
 
-	return;
+void
+free_bitmap_buffer(void)
+{
+	free_bitmap1_buffer();
+	free_bitmap2_buffer();
 }
 
 int
@@ -4862,10 +4993,21 @@ create_dump_bitmap(void)
 	int ret = FALSE;
 
 	if (info->flag_cyclic) {
-		if (!prepare_bitmap_buffer_cyclic())
-			goto out;
 
-		info->num_dumpable = get_num_dumpable_cyclic();
+		if (info->flag_elf_dumpfile) {
+			if (!prepare_bitmap_buffer_cyclic())
+				goto out;
+
+			info->num_dumpable = get_num_dumpable_cyclic();
+		} else {
+			if (!prepare_bitmap2_buffer_cyclic())
+				goto out;
+
+			info->num_dumpable = get_num_dumpable_cyclic();
+
+			free_bitmap2_buffer();
+		}
+
 	} else {
 		if (!prepare_bitmap_buffer())
 			goto out;
@@ -6564,7 +6706,7 @@ out:
 }
 
 int
-write_kdump_bitmap_cyclic(void)
+write_kdump_bitmap1_cyclic(void)
 {
 	off_t offset;
         int increment;
@@ -6576,10 +6718,30 @@ write_kdump_bitmap_cyclic(void)
 		return FALSE;
 
 	offset = info->offset_bitmap1;
-	if (!write_buffer(info->fd_dumpfile, offset,
+	if (!write_buffer(info->fd_dumpfile, offset + info->bufsize_cyclic *
+			  (info->cyclic_start_pfn / info->pfn_cyclic),
 			  info->partial_bitmap1, increment, info->name_dumpfile))
 		goto out;
 
+	ret = TRUE;
+out:
+	return ret;
+}
+
+int
+write_kdump_bitmap2_cyclic(void)
+{
+	off_t offset;
+	int increment;
+	int ret = FALSE;
+
+	increment = divideup(info->cyclic_end_pfn - info->cyclic_start_pfn,
+			     BITPERBYTE);
+
+	if (info->flag_elf_dumpfile)
+		return FALSE;
+
+	offset = info->offset_bitmap1;
 	offset += info->len_bitmap / 2;
 	if (!write_buffer(info->fd_dumpfile, offset,
 			  info->partial_bitmap2, increment, info->name_dumpfile))
@@ -6633,6 +6795,30 @@ write_kdump_pages_and_bitmap_cyclic(struct cache_data *cd_header, struct cache_d
 	}
 
 	/*
+	 * Write the 1st bitmap
+	 */
+	if (!prepare_bitmap1_buffer_cyclic())
+		return FALSE;
+
+	info->cyclic_start_pfn = 0;
+	info->cyclic_end_pfn = 0;
+	for (pfn = 0; pfn < info->max_mapnr; pfn++) {
+		if (is_cyclic_region(pfn))
+			continue;
+		if (!update_cyclic_region(pfn))
+			return FALSE;
+		if (!create_1st_bitmap_cyclic())
+			return FALSE;
+		if (!write_kdump_bitmap1_cyclic())
+			return FALSE;
+	}
+
+	free_bitmap1_buffer();
+
+	if (!prepare_bitmap2_buffer_cyclic())
+		return FALSE;
+
+	/*
 	 * Write pages and bitmap cyclically.
 	 */
 	info->cyclic_start_pfn = 0;
@@ -6647,7 +6833,7 @@ write_kdump_pages_and_bitmap_cyclic(struct cache_data *cd_header, struct cache_d
 		if (!write_kdump_pages_cyclic(cd_header, cd_page, &pd_zero, &offset_data))
 			return FALSE;
 
-		if (!write_kdump_bitmap_cyclic())
+		if (!write_kdump_bitmap2_cyclic())
 			return FALSE;
         }
 
@@ -8681,8 +8867,14 @@ calculate_cyclic_buffer_size(void) {
 	 * should be 40% of free memory to keep the size of cyclic buffer
 	 * within 80% of free memory.
 	 */
-	free_size = get_free_memory_size() * 0.4;
-	needed_size = (info->max_mapnr * 2) / BITPERBYTE;
+	if (info->flag_elf_dumpfile) {
+		free_size = get_free_memory_size() * 0.4;
+		needed_size = (info->max_mapnr * 2) / BITPERBYTE;
+	} else {
+		free_size = get_free_memory_size() * 0.8;
+		needed_size = info->max_mapnr / BITPERBYTE;
+	}
+
 	/* if --split was specified cyclic buffer allocated per dump file */
 	if (info->num_dumpfile > 1)
 		needed_size /= info->num_dumpfile;


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Re: [PATCH v2 0/2] makedumpfile: write out a whole part of the 1st bitmap before entering cyclic process

[Atsushi Kumagai]

(2013/11/05 0:23), HATAYAMA Daisuke wrote:
> This patch set changes the implementation so that a whole part of the
> 1st bitmap is written out before entering cyclic process. By this:
>
> - we no longer need to keep buffer for the 1st bitmap during cyclic
>    process, and
>
> - it's possible for incomplete crash dump, for example, generated in
>    case of ENOSPC, to avoid the case that we don't know where memory is
>    present.
>
> Note that this patch only deal with a conversion from ELF to
> kdump-compressed format only, not from ELF to ELF.
>
> ChangeLog
>
> v1 => v2)
>
> - Fix a bug of assigning wrong cyclic buffer size from free memory
>    size.

Thanks for fixing, I'll merge this into v1.5.5.


Atsushi Kumagai

>
> ---
>
> HATAYAMA Daisuke (2):
>        Use memset() to improve the 1st bitmap initialization performance
>        Write out a whole part of the 1st bitmap before entering cyclic process
>
>
>   makedumpfile.c |  268 ++++++++++++++++++++++++++++++++++++++++++++++++++------
>   1 file changed, 241 insertions(+), 27 deletions(-)
>

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