[PATCH 1/2] use raw i/o and root device to use less memory

Cliff Wickman cpw at sgi.com
Wed Jul 8 15:54:30 PDT 2015


Hello Kumagai-san,

I had not seen your mail of 5/21 (that you refer to below).  I don't know how
I missed it.  It was just a coincidence that I decided to fit my patches into
your current version shortly after that (6/29).

I've been testing.  And you have done a nice job of constant memory usage when
in cyclic mode.  By 'reclaimable' I assume that you mean that you re-use the
same regions of the same files so that the page cache is not expanded.

And indeed I saw no OOM conditions when using cyclic mode within a 450M crashkernel
region while dumping a 2TB memory.  I haven't had access to a bigger memory yet for
further tests.

In cyclic mode it writes a 3.5G dump in about 480 seconds.

If I use my proposed -e option (exclude unused page structs) I put makedumpfile
into non-cyclic mode and immediately get killed by OOM.

If I use my proposed -j option (use direct i/o for the dump and bit maps) I put
makedumpfile into non-cyclic mode but do not run out of memory because I'm not
using page cache or a tmpfs.
It writes a 3.5G dump in about 800 seconds.
So there is definitely a big advantage to cached i/o and cyclic mode.

If I use both -e and -j it writes a 440M dump in 430 seconds.
This is therefore the fastest way to dump a large memory, even though it is
using direct i/o.  The -e is causing it to drop 7M unneeded pages from the dump.

What would be really nice is to have a -e option in cyclic mode -- the best
of both.

It's not very easy to do, however.  I need some pointers to the proper place to
implement this in cyclic mode.
If you look at the patch that implements -e 
  [PATCH 2/2] exclude page structures of non-dumped pages
you will see that find_unused_vmemmap_pages() is comparing the entire map of
existing pages (bitmap1) and dumpable pages (bitmap2).  From that it derives
the vmemmap pages that do not really need to be dumped.

I assume that this could be done using the equivalent 2 bit maps at each cycle.
Do you agree?

-Cliff

On Tue, Jul 07, 2015 at 07:42:26AM +0000, Atsushi Kumagai wrote:
> Hello Cliff,
> 
> Did you overlook my comment below ?
> 
>  - http://lists.infradead.org/pipermail/kexec/2015-May/013823.html
>     I understood that you suggested direct I/O to reduce the memory
>     consumption without multi cycle processing, but I don't understand
>     the actual benefit yet because page cache is reclaimable and it's
>     generally usable. Does it practically affect the minimum size of
>     crashkernel= which makedumpfile can work on ?
>     
>     Instead, if you say frequent page cache reclaiming will cause performance
>     regression, it sounds reasonable. However, even from the view point of
>     performance, page cached I/O is better than direct I/O according to your
>     test results.
> 
> Please explain the practical benefit of Direct I/O, otherwise I can't
> decide to accept this.
> 
> 
> Thanks
> Atsushi Kumagai
> 
> >From: Cliff Wickman <cpw at sgi.com>
> >
> >Applies to version 1.5.8
> >
> >This patch adds a -j to makedumpfile. With this option it uses direct i/o on the dump
> >file and the bitmap file, thus enabling makedumpfile to run mode in a fairly small
> >crashkernel area without using cyclic mode. It can dump a system with many terabytes
> >of memory using crashkernel=450M.
> >
> >Without direct i/o the crash kernel will use kernel page cache for the writes.  This
> >will use up a great deal of the crash kernel's alloted memory.
> >
> >The -j option will also implicitly avoid cyclic mode.  Cyclic mode is slower, and
> >is not needed if we use direct i/o.
> >Direct i/o is of course a bit slower, but not significantly slower when used in this
> >almost-entirely sequential fashion.
> >
> >---
> > makedumpfile.c |  419 ++++++++++++++++++++++++++++++++++++++++++++++-----------
> > makedumpfile.h |    7
> > print_info.c   |    7
> > 3 files changed, 352 insertions(+), 81 deletions(-)
> >
> >Index: makedumpfile/makedumpfile.h
> >===================================================================
> >--- makedumpfile.orig/makedumpfile.h
> >+++ makedumpfile/makedumpfile.h
> >@@ -18,6 +18,7 @@
> >
> > #include <stdio.h>
> > #include <stdlib.h>
> >+#define __USE_GNU
> > #include <fcntl.h>
> > #include <gelf.h>
> > #include <sys/stat.h>
> >@@ -222,6 +223,7 @@ isAnon(unsigned long mapping)
> > #define FILENAME_BITMAP		"kdump_bitmapXXXXXX"
> > #define FILENAME_STDOUT		"STDOUT"
> > #define MAP_REGION		(4096*1024)
> >+#define DIRECT_ALIGN		(512)
> >
> > /*
> >  * Minimam vmcore has 2 ProgramHeaderTables(PT_NOTE and PT_LOAD).
> >@@ -897,7 +899,8 @@ struct dump_bitmap {
> > 	int		fd;
> > 	int		no_block;
> > 	char		*file_name;
> >-	char		buf[BUFSIZE_BITMAP];
> >+	char		*buf;
> >+	char		*buf_malloced;
> > 	off_t		offset;
> > };
> >
> >@@ -905,6 +908,7 @@ struct cache_data {
> > 	int	fd;
> > 	char	*file_name;
> > 	char	*buf;
> >+	char    *buf_malloced;
> > 	size_t	buf_size;
> > 	size_t	cache_size;
> > 	off_t	offset;
> >@@ -1874,6 +1878,7 @@ struct elf_prstatus {
> > #define OPT_GENERATE_VMCOREINFO 'g'
> > #define OPT_HELP                'h'
> > #define OPT_READ_VMCOREINFO     'i'
> >+#define OPT_DIRECT_IO		'j'
> > #define OPT_COMPRESS_LZO        'l'
> > #define OPT_COMPRESS_SNAPPY     'p'
> > #define OPT_REARRANGE           'R'
> >Index: makedumpfile/print_info.c
> >===================================================================
> >--- makedumpfile.orig/print_info.c
> >+++ makedumpfile/print_info.c
> >@@ -58,7 +58,7 @@ print_usage(void)
> > 	MSG("\n");
> > 	MSG("Usage:\n");
> > 	MSG("  Creating DUMPFILE:\n");
> >-	MSG("  # makedumpfile    [-c|-l|-p|-E] [-d DL] [-x VMLINUX|-i VMCOREINFO] VMCORE\n");
> >+	MSG("  # makedumpfile    [-c|-l|-p|-E] [-d DL] [-j] [-x VMLINUX|-i VMCOREINFO] VMCORE\n");
> > 	MSG("    DUMPFILE\n");
> > 	MSG("\n");
> > 	MSG("  Creating DUMPFILE with filtered kernel data specified through filter config\n");
> >@@ -108,6 +108,11 @@ print_usage(void)
> > 	MSG("      -E option, because the ELF format does not support compressed data.\n");
> > 	MSG("      THIS IS ONLY FOR THE CRASH UTILITY.\n");
> > 	MSG("\n");
> >+	MSG("  [-j]:\n");
> >+	MSG("      Use raw (O_DIRECT) i/o on dump and bitmap files to avoid expanding kernel pagecache.\n");
> >+	MSG("      This allows the dump of a very large memory within a constricted\n");
> >+	MSG("      (e.g. 450M) crashkernel space.\n");
> >+	MSG("\n");
> > 	MSG("  [-d DL]:\n");
> > 	MSG("      Specify the type of unnecessary page for analysis.\n");
> > 	MSG("      Pages of the specified type are not copied to DUMPFILE. The page type\n");
> >Index: makedumpfile/makedumpfile.c
> >===================================================================
> >--- makedumpfile.orig/makedumpfile.c
> >+++ makedumpfile/makedumpfile.c
> >@@ -85,8 +85,11 @@ mdf_pfn_t pfn_free;
> > mdf_pfn_t pfn_hwpoison;
> >
> > mdf_pfn_t num_dumped;
> >+long blocksize;
> >
> > int retcd = FAILED;	/* return code */
> >+// directioflag is rawio on the dumpfile and bitmap file
> >+int directioflag = 0;
> >
> > #define INITIALIZE_LONG_TABLE(table, value) \
> > do { \
> >@@ -991,10 +994,17 @@ int
> > open_dump_file(void)
> > {
> > 	int fd;
> >-	int open_flags = O_RDWR|O_CREAT|O_TRUNC;
> >+	int open_flags;
> >
> >+	if (directioflag)
> >+		open_flags = O_RDWR|O_CREAT|O_TRUNC|O_DIRECT;
> >+	else
> >+		open_flags = O_RDWR|O_CREAT|O_TRUNC;
> >+
> >+#if 0
> > 	if (!info->flag_force)
> > 		open_flags |= O_EXCL;
> >+#endif
> >
> > 	if (info->flag_flatten) {
> > 		fd = STDOUT_FILENO;
> >@@ -1030,12 +1040,40 @@ check_dump_file(const char *path)
> > int
> > open_dump_bitmap(void)
> > {
> >-	int i, fd;
> >-	char *tmpname;
> >-
> >-	tmpname = getenv("TMPDIR");
> >-	if (!tmpname)
> >-		tmpname = "/tmp";
> >+	int i, fd, flags;
> >+	char *tmpname, *cp;
> >+	char prefix[100];
> >+	int len;
> >+
> >+	/* -j: saving memory by doing direct i/o, so also avoid /tmp for the bit map files
> >+	 *     because /tmp is using tmpfs */
> >+	if (!directioflag) {
> >+		tmpname = getenv("TMPDIR");
> >+		if (!tmpname)
> >+			tmpname = "/tmp";
> >+	} else {
> >+		/* for the crash kernel environment use the prefix of
> >+ 		   the dump name   e.g. /mnt//var/.... */
> >+		if (!strchr(info->name_dumpfile,'v')) {
> >+			printf("no /var found in name_dumpfile %s\n",
> >+			info->name_dumpfile);
> >+			exit(1);
> >+		} else {
> >+			cp = strchr(info->name_dumpfile,'v');
> >+			if (strncmp(cp-1, "/var", 4)) {
> >+				printf("no /var found in name_dumpfile %s\n",
> >+					info->name_dumpfile);
> >+				exit(1);
> >+			}
> >+		}
> >+		len = cp - info->name_dumpfile - 1;
> >+		strncpy(prefix, info->name_dumpfile, len);
> >+		if (*(prefix + len - 1) == '/')
> >+			len -= 1;
> >+		*(prefix + len) = '\0';
> >+		tmpname = prefix;
> >+		strcat(tmpname, "/");
> >+ 	}
> >
> > 	if ((info->name_bitmap = (char *)malloc(sizeof(FILENAME_BITMAP) +
> > 						strlen(tmpname) + 1)) == NULL) {
> >@@ -1044,9 +1082,12 @@ open_dump_bitmap(void)
> > 		return FALSE;
> > 	}
> > 	strcpy(info->name_bitmap, tmpname);
> >-	strcat(info->name_bitmap, "/");
> > 	strcat(info->name_bitmap, FILENAME_BITMAP);
> >-	if ((fd = mkstemp(info->name_bitmap)) < 0) {
> >+	if (directioflag)
> >+		flags = O_RDWR|O_CREAT|O_TRUNC|O_DIRECT;
> >+	else
> >+		flags = O_RDWR|O_CREAT|O_TRUNC;
> >+	if ((fd = open(info->name_bitmap, flags)) < 0) {
> > 		ERRMSG("Can't open the bitmap file(%s). %s\n",
> > 		    info->name_bitmap, strerror(errno));
> > 		return FALSE;
> >@@ -3020,6 +3061,7 @@ initialize_bitmap_memory(void)
> > 	struct dump_bitmap *bmp;
> > 	off_t bitmap_offset;
> > 	off_t bitmap_len, max_sect_len;
> >+	char *cp;
> > 	mdf_pfn_t pfn;
> > 	int i, j;
> > 	long block_size;
> >@@ -3041,7 +3083,14 @@ initialize_bitmap_memory(void)
> > 	bmp->fd        = info->fd_memory;
> > 	bmp->file_name = info->name_memory;
> > 	bmp->no_block  = -1;
> >-	memset(bmp->buf, 0, BUFSIZE_BITMAP);
> >+	if ((cp = malloc(blocksize + DIRECT_ALIGN)) == NULL) {
> >+		ERRMSG("Can't allocate memory for the bitmap buffer. %s\n",
> >+		    strerror(errno));
> >+		exit(1);
> >+	}
> >+	bmp->buf_malloced = cp;
> >+	bmp->buf = cp - ((unsigned long)cp % DIRECT_ALIGN) + DIRECT_ALIGN;
> >+	memset(bmp->buf, 0, blocksize);
> > 	bmp->offset = bitmap_offset + bitmap_len / 2;
> > 	info->bitmap_memory = bmp;
> >
> >@@ -3053,6 +3102,7 @@ initialize_bitmap_memory(void)
> > 	if (info->valid_pages == NULL) {
> > 		ERRMSG("Can't allocate memory for the valid_pages. %s\n",
> > 		    strerror(errno));
> >+		free(bmp->buf_malloced);
> > 		free(bmp);
> > 		return FALSE;
> > 	}
> >@@ -3355,9 +3405,18 @@ out:
> > void
> > initialize_bitmap(struct dump_bitmap *bitmap)
> > {
> >+	char *cp;
> >+
> > 	bitmap->fd        = info->fd_bitmap;
> > 	bitmap->file_name = info->name_bitmap;
> > 	bitmap->no_block  = -1;
> >+	if ((cp = malloc(blocksize + DIRECT_ALIGN)) == NULL) {
> >+		ERRMSG("Can't allocate memory for the bitmap buffer. %s\n",
> >+		    strerror(errno));
> >+		exit(1);
> >+	}
> >+	bitmap->buf_malloced = cp;
> >+	bitmap->buf = cp - ((unsigned long)cp % DIRECT_ALIGN) + DIRECT_ALIGN;
> > 	memset(bitmap->buf, 0, BUFSIZE_BITMAP);
> > }
> >
> >@@ -3422,9 +3481,9 @@ set_bitmap(struct dump_bitmap *bitmap, m
> > 	byte = (pfn%PFN_BUFBITMAP)>>3;
> > 	bit  = (pfn%PFN_BUFBITMAP) & 7;
> > 	if (val)
> >-		bitmap->buf[byte] |= 1<<bit;
> >+		*(bitmap->buf + byte) |= 1<<bit;
> > 	else
> >-		bitmap->buf[byte] &= ~(1<<bit);
> >+		*(bitmap->buf + byte) &= ~(1<<bit);
> >
> > 	return TRUE;
> > }
> >@@ -3607,6 +3666,29 @@ read_cache(struct cache_data *cd)
> > 	return TRUE;
> > }
> >
> >+void
> >+fill_to_offset(struct cache_data *cd, int blocksize)
> >+{
> >+	off_t current;
> >+	long num_blocks;
> >+	long i;
> >+
> >+	current = lseek(cd->fd, 0, SEEK_CUR);
> >+	if ((cd->offset - current) % blocksize) {
> >+		printf("ERROR: fill area is %#lx\n", cd->offset - current);
> >+		exit(1);
> >+	}
> >+	if (cd->cache_size < blocksize) {
> >+		printf("ERROR: cache buf is only %ld\n", cd->cache_size);
> >+		exit(1);
> >+	}
> >+	num_blocks = (cd->offset - current) / blocksize;
> >+	for (i = 0; i < num_blocks; i++) {
> >+		write(cd->fd, cd->buf, blocksize);
> >+	}
> >+	return;
> >+}
> >+
> > int
> > is_bigendian(void)
> > {
> >@@ -3676,6 +3758,14 @@ write_buffer(int fd, off_t offset, void
> > int
> > write_cache(struct cache_data *cd, void *buf, size_t size)
> > {
> >+	/* sanity check; do not overflow this buffer */
> >+	/* (it is of cd->cache_size + info->page_size) */
> >+	if (size > ((cd->cache_size - cd->buf_size) + info->page_size)) {
> >+		fprintf(stderr, "write_cache buffer overflow! size %#lx\n",
> >+			size);
> >+		exit(1);
> >+	}
> >+
> > 	memcpy(cd->buf + cd->buf_size, buf, size);
> > 	cd->buf_size += size;
> >
> >@@ -3688,6 +3778,8 @@ write_cache(struct cache_data *cd, void
> >
> > 	cd->buf_size -= cd->cache_size;
> > 	memcpy(cd->buf, cd->buf + cd->cache_size, cd->buf_size);
> >+	if (cd->buf_size)
> >+		memcpy(cd->buf, cd->buf + cd->cache_size, cd->buf_size);
> > 	cd->offset += cd->cache_size;
> > 	return TRUE;
> > }
> >@@ -3719,6 +3811,21 @@ write_cache_zero(struct cache_data *cd,
> > 	return write_cache_bufsz(cd);
> > }
> >
> >+/* flush the full cache to the file */
> >+int
> >+write_cache_flush(struct cache_data *cd)
> >+{
> >+	if (cd->buf_size == 0)
> >+		return TRUE;
> >+	if (cd->buf_size < cd->cache_size) {
> >+		memset(cd->buf + cd->buf_size, 0, cd->cache_size - cd->buf_size);
> >+	}
> >+	cd->buf_size = cd->cache_size;
> >+	if (!write_cache_bufsz(cd))
> >+		return FALSE;
> >+	return TRUE;
> >+}
> >+
> > int
> > read_buf_from_stdin(void *buf, int buf_size)
> > {
> >@@ -4608,11 +4715,19 @@ create_1st_bitmap(void)
> > {
> > 	int i;
> > 	unsigned int num_pt_loads = get_num_pt_loads();
> >- 	char buf[info->page_size];
> >+ 	char *buf;
> > 	mdf_pfn_t pfn, pfn_start, pfn_end, pfn_bitmap1;
> > 	unsigned long long phys_start, phys_end;
> > 	struct timeval tv_start;
> > 	off_t offset_page;
> >+	char *cp;
> >+
> >+	if ((cp = malloc(blocksize + DIRECT_ALIGN)) == NULL) {
> >+		ERRMSG("Can't allocate memory for the bitmap buffer. %s\n",
> >+		    strerror(errno));
> >+		exit(1);
> >+	}
> >+	buf = cp - ((unsigned long)cp % DIRECT_ALIGN) + DIRECT_ALIGN;
> >
> > 	if (info->flag_refiltering)
> > 		return copy_1st_bitmap_from_memory();
> >@@ -4623,7 +4738,7 @@ create_1st_bitmap(void)
> > 	/*
> > 	 * At first, clear all the bits on the 1st-bitmap.
> > 	 */
> >-	memset(buf, 0, sizeof(buf));
> >+	memset(buf, 0, blocksize);
> >
> > 	if (lseek(info->bitmap1->fd, info->bitmap1->offset, SEEK_SET) < 0) {
> > 		ERRMSG("Can't seek the bitmap(%s). %s\n",
> >@@ -5172,9 +5287,17 @@ int
> > copy_bitmap(void)
> > {
> > 	off_t offset;
> >-	unsigned char buf[info->page_size];
> >+	unsigned char *buf;
> >+	unsigned char *cp;
> >  	const off_t failed = (off_t)-1;
> >
> >+	if ((cp = malloc(blocksize + DIRECT_ALIGN)) == NULL) {
> >+		ERRMSG("Can't allocate memory for the bitmap buffer. %s\n",
> >+		    strerror(errno));
> >+		exit(1);
> >+	}
> >+	buf = cp - ((unsigned long)cp % DIRECT_ALIGN) + DIRECT_ALIGN;
> >+
> > 	offset = 0;
> > 	while (offset < (info->len_bitmap / 2)) {
> > 		if (lseek(info->bitmap1->fd, info->bitmap1->offset + offset,
> >@@ -5183,7 +5306,7 @@ copy_bitmap(void)
> > 			    info->name_bitmap, strerror(errno));
> > 			return FALSE;
> > 		}
> >-		if (read(info->bitmap1->fd, buf, sizeof(buf)) != sizeof(buf)) {
> >+		if (read(info->bitmap1->fd, buf, blocksize) != blocksize) {
> > 			ERRMSG("Can't read the dump memory(%s). %s\n",
> > 			    info->name_memory, strerror(errno));
> > 			return FALSE;
> >@@ -5194,12 +5317,12 @@ copy_bitmap(void)
> > 			    info->name_bitmap, strerror(errno));
> > 			return FALSE;
> > 		}
> >-		if (write(info->bitmap2->fd, buf, sizeof(buf)) != sizeof(buf)) {
> >+		if (write(info->bitmap2->fd, buf, blocksize) != blocksize) {
> > 			ERRMSG("Can't write the bitmap(%s). %s\n",
> > 		    	info->name_bitmap, strerror(errno));
> > 			return FALSE;
> > 		}
> >-		offset += sizeof(buf);
> >+		offset += blocksize;
> > 	}
> >
> > 	return TRUE;
> >@@ -5357,6 +5480,8 @@ void
> > free_bitmap1_buffer(void)
> > {
> > 	if (info->bitmap1) {
> >+		if (info->bitmap1->buf_malloced)
> >+			free(info->bitmap1->buf_malloced);
> > 		free(info->bitmap1);
> > 		info->bitmap1 = NULL;
> > 	}
> >@@ -5366,6 +5491,8 @@ void
> > free_bitmap2_buffer(void)
> > {
> > 	if (info->bitmap2) {
> >+		if (info->bitmap2->buf_malloced)
> >+			free(info->bitmap2->buf_malloced);
> > 		free(info->bitmap2);
> > 		info->bitmap2 = NULL;
> > 	}
> >@@ -5491,25 +5618,31 @@ get_loads_dumpfile(void)
> > int
> > prepare_cache_data(struct cache_data *cd)
> > {
> >+	char *cp;
> >+
> > 	cd->fd         = info->fd_dumpfile;
> > 	cd->file_name  = info->name_dumpfile;
> > 	cd->cache_size = info->page_size << info->block_order;
> > 	cd->buf_size   = 0;
> > 	cd->buf        = NULL;
> >
> >-	if ((cd->buf = malloc(cd->cache_size + info->page_size)) == NULL) {
> >+	if ((cp = malloc(cd->cache_size + info->page_size + DIRECT_ALIGN)) == NULL) {
> > 		ERRMSG("Can't allocate memory for the data buffer. %s\n",
> > 		    strerror(errno));
> > 		return FALSE;
> > 	}
> >+	cd->buf_malloced = cp;
> >+	cd->buf = cp - ((unsigned long)cp % DIRECT_ALIGN) + DIRECT_ALIGN;
> > 	return TRUE;
> > }
> >
> > void
> > free_cache_data(struct cache_data *cd)
> > {
> >-	free(cd->buf);
> >+	if (cd->buf_malloced)
> >+		free(cd->buf_malloced);
> > 	cd->buf = NULL;
> >+	cd->buf_malloced = NULL;
> > }
> >
> > int
> >@@ -5765,19 +5898,21 @@ out:
> > }
> >
> > int
> >-write_kdump_header(void)
> >+write_kdump_header(struct cache_data *cd)
> > {
> > 	int ret = FALSE;
> > 	size_t size;
> > 	off_t offset_note, offset_vmcoreinfo;
> >-	unsigned long size_note, size_vmcoreinfo;
> >+	unsigned long size_note, size_vmcoreinfo, remaining_size_note;
> >+	unsigned long write_size, room;
> > 	struct disk_dump_header *dh = info->dump_header;
> > 	struct kdump_sub_header kh;
> >-	char *buf = NULL;
> >+	char *buf = NULL, *cp;
> >
> > 	if (info->flag_elf_dumpfile)
> > 		return FALSE;
> >
> >+	/* uses reads of /proc/vmcore */
> > 	get_pt_note(&offset_note, &size_note);
> >
> > 	/*
> >@@ -5794,6 +5929,7 @@ write_kdump_header(void)
> > 	dh->bitmap_blocks  = divideup(info->len_bitmap, dh->block_size);
> > 	memcpy(&dh->timestamp, &info->timestamp, sizeof(dh->timestamp));
> > 	memcpy(&dh->utsname, &info->system_utsname, sizeof(dh->utsname));
> >+	blocksize = dh->block_size;
> > 	if (info->flag_compress & DUMP_DH_COMPRESSED_ZLIB)
> > 		dh->status |= DUMP_DH_COMPRESSED_ZLIB;
> > #ifdef USELZO
> >@@ -5806,7 +5942,7 @@ write_kdump_header(void)
> > #endif
> >
> > 	size = sizeof(struct disk_dump_header);
> >-	if (!write_buffer(info->fd_dumpfile, 0, dh, size, info->name_dumpfile))
> >+	if (!write_cache(cd, dh, size))
> > 		return FALSE;
> >
> > 	/*
> >@@ -5862,9 +5998,21 @@ write_kdump_header(void)
> > 				goto out;
> > 		}
> >
> >-		if (!write_buffer(info->fd_dumpfile, kh.offset_note, buf,
> >-		    kh.size_note, info->name_dumpfile))
> >-			goto out;
> >+		/* the note may be huge, so do this in a loop to not
> >+		   overflow the cache */
> >+		remaining_size_note = kh.size_note;
> >+		cp = buf;
> >+		do {
> >+			room = cd->cache_size - cd->buf_size;
> >+			if (remaining_size_note > room)
> >+				write_size = room;
> >+			else
> >+				write_size = remaining_size_note;
> >+			if (!write_cache(cd, cp, write_size))
> >+				goto out;
> >+			remaining_size_note -= write_size;
> >+			cp += write_size;
> >+		} while (remaining_size_note);
> >
> > 		if (has_vmcoreinfo()) {
> > 			get_vmcoreinfo(&offset_vmcoreinfo, &size_vmcoreinfo);
> >@@ -5880,8 +6028,7 @@ write_kdump_header(void)
> > 			kh.size_vmcoreinfo = size_vmcoreinfo;
> > 		}
> > 	}
> >-	if (!write_buffer(info->fd_dumpfile, dh->block_size, &kh,
> >-	    size, info->name_dumpfile))
> >+	if (!write_cache(cd, &kh, size))
> > 		goto out;
> >
> > 	info->sub_header = kh;
> >@@ -6631,13 +6778,15 @@ write_elf_pages_cyclic(struct cache_data
> > }
> >
> > int
> >-write_kdump_pages(struct cache_data *cd_header, struct cache_data *cd_page)
> >+write_kdump_pages(struct cache_data *cd_descs, struct cache_data *cd_page)
> > {
> > 	mdf_pfn_t pfn, per, num_dumpable;
> > 	mdf_pfn_t start_pfn, end_pfn;
> > 	unsigned long size_out;
> >+	long prefix;
> > 	struct page_desc pd, pd_zero;
> > 	off_t offset_data = 0;
> >+	off_t initial_offset_data;
> > 	struct disk_dump_header *dh = info->dump_header;
> > 	unsigned char buf[info->page_size], *buf_out = NULL;
> > 	unsigned long len_buf_out;
> >@@ -6645,8 +6794,12 @@ write_kdump_pages(struct cache_data *cd_
> > 	struct timeval tv_start;
> > 	const off_t failed = (off_t)-1;
> > 	unsigned long len_buf_out_zlib, len_buf_out_lzo, len_buf_out_snappy;
> >+	int saved_bytes = 0;
> >+	int cpysize;
> >+	char *save_block1, *save_block_cur, *save_block2;
> >
> > 	int ret = FALSE;
> >+	int status;
> >
> > 	if (info->flag_elf_dumpfile)
> > 		return FALSE;
> >@@ -6688,13 +6841,42 @@ write_kdump_pages(struct cache_data *cd_
> > 	per = per ? per : 1;
> >
> > 	/*
> >-	 * Calculate the offset of the page data.
> >+	 * Calculate the offset of the page_desc's and page data.
> > 	 */
> >-	cd_header->offset
> >+	cd_descs->offset
> > 	    = (DISKDUMP_HEADER_BLOCKS + dh->sub_hdr_size + dh->bitmap_blocks)
> > 		* dh->block_size;
> >-	cd_page->offset = cd_header->offset + sizeof(page_desc_t)*num_dumpable;
> >-	offset_data  = cd_page->offset;
> >+
> >+	/* this is already a pagesize multiple, so well-formed for i/o */
> >+
> >+	cd_page->offset = cd_descs->offset + (sizeof(page_desc_t) * num_dumpable);
> >+	offset_data = cd_page->offset;
> >+
> >+	/* for i/o, round this page data offset down to a block boundary */
> >+	prefix = cd_page->offset % blocksize;
> >+	cd_page->offset -= prefix;
> >+	initial_offset_data = cd_page->offset;
> >+	cd_page->buf_size = prefix;
> >+	memset(cd_page->buf, 0, prefix);
> >+
> >+	fill_to_offset(cd_descs, blocksize);
> >+
> >+	if ((save_block1 = malloc(blocksize * 2)) == NULL) {
> >+		ERRMSG("Can't allocate memory for save block. %s\n",
> >+		       strerror(errno));
> >+		goto out;
> >+	}
> >+	/* put on block address boundary for well-rounded i/o */
> >+	save_block1 += (blocksize - (unsigned long)save_block1 % blocksize);
> >+	save_block_cur = save_block1 + prefix;
> >+	saved_bytes += prefix;
> >+	if ((save_block2 = malloc(blocksize + DIRECT_ALIGN)) == NULL) {
> >+		ERRMSG("Can't allocate memory for save block2. %s\n",
> >+		       strerror(errno));
> >+		goto out;
> >+	}
> >+	/* put on block address boundary for well-rounded i/o */
> >+	save_block2 += (DIRECT_ALIGN - (unsigned long)save_block2 % DIRECT_ALIGN);
> >
> > 	/*
> > 	 * Set a fileoffset of Physical Address 0x0.
> >@@ -6718,6 +6900,14 @@ write_kdump_pages(struct cache_data *cd_
> > 		memset(buf, 0, pd_zero.size);
> > 		if (!write_cache(cd_page, buf, pd_zero.size))
> > 			goto out;
> >+
> >+		cpysize = pd_zero.size;
> >+		if ((saved_bytes + cpysize) > blocksize)
> >+			cpysize = blocksize - saved_bytes;
> >+		memcpy(save_block_cur, buf, cpysize);
> >+		saved_bytes += cpysize;
> >+		save_block_cur += cpysize;
> >+
> > 		offset_data  += pd_zero.size;
> > 	}
> > 	if (info->flag_split) {
> >@@ -6751,7 +6941,7 @@ write_kdump_pages(struct cache_data *cd_
> > 		 */
> > 		if ((info->dump_level & DL_EXCLUDE_ZERO)
> > 		    && is_zero_page(buf, info->page_size)) {
> >-			if (!write_cache(cd_header, &pd_zero, sizeof(page_desc_t)))
> >+			if (!write_cache(cd_descs, &pd_zero, sizeof(page_desc_t)))
> > 				goto out;
> > 			pfn_zero++;
> > 			continue;
> >@@ -6799,25 +6989,68 @@ write_kdump_pages(struct cache_data *cd_
> > 		/*
> > 		 * Write the page header.
> > 		 */
> >-		if (!write_cache(cd_header, &pd, sizeof(page_desc_t)))
> >+		if (!write_cache(cd_descs, &pd, sizeof(page_desc_t)))
> > 			goto out;
> >
> > 		/*
> > 		 * Write the page data.
> > 		 */
> >+		/* kludge: save the partial block where page desc's and data overlap */
> >+		/* (this is the second part of the full block (save_block) where
> >+		    they overlap) */
> >+		if (saved_bytes < blocksize) {
> >+			memcpy(save_block_cur, buf, pd.size);
> >+			saved_bytes += pd.size;
> >+			save_block_cur += pd.size;
> >+		}
> > 		if (!write_cache(cd_page, pd.flags ? buf_out : buf, pd.size))
> > 			goto out;
> > 	}
> >
> > 	/*
> >-	 * Write the remainder.
> >+	 * Write the remainder (well-formed blocks)
> > 	 */
> >-	if (!write_cache_bufsz(cd_page))
> >-		goto out;
> >-	if (!write_cache_bufsz(cd_header))
> >+	/* adjust the cd_descs to write out only full blocks beyond the
> >+	   data in the buffer */
> >+	if (cd_descs->buf_size % blocksize) {
> >+		cd_descs->buf_size +=
> >+			(blocksize - (cd_descs->buf_size % blocksize));
> >+		cd_descs->cache_size = cd_descs->buf_size;
> >+	}
> >+	if (!write_cache_flush(cd_descs))
> > 		goto out;
> >
> > 	/*
> >+	 * kludge: the page data will overwrite the last block of the page_desc's,
> >+	 * so re-construct a block from:
> >+	 *   the last block of the page_desc's (length 'prefix') (will read into
> >+	 *   save_block2) and the end (4096-prefix) of the page data we saved in
> >+	 *   save_block1.
> >+	 */
> >+	if (!write_cache_flush(cd_page))
> >+ 		goto out;
> >+
> >+	if (lseek(cd_page->fd, initial_offset_data, SEEK_SET) == failed) {
> >+		printf("kludge: seek to %#lx, fd %d failed errno %d\n",
> >+			initial_offset_data, cd_page->fd, errno);
> >+		exit(1);
> >+	}
> >+	if (read(cd_page->fd, save_block2, blocksize) != blocksize) {
> >+		printf("kludge: read block2 failed\n");
> >+		exit(1);
> >+	}
> >+	/* combine the overlapping parts into save_block1 */
> >+	memcpy(save_block1, save_block2, prefix);
> >+
> >+	if (lseek(cd_page->fd, initial_offset_data, SEEK_SET) == failed) {
> >+		printf("kludge: seek to %#lx, fd %d failed errno %d\n",
> >+			initial_offset_data, cd_page->fd, errno);
> >+		exit(1);
> >+	}
> >+	status = write(cd_page->fd, save_block1, blocksize);
> >+	/* end of kludged block */
> >+
> >+	/*
> > 	 * print [100 %]
> > 	 */
> > 	print_progress(PROGRESS_COPY, num_dumpable, num_dumpable);
> >@@ -6826,8 +7059,6 @@ write_kdump_pages(struct cache_data *cd_
> >
> > 	ret = TRUE;
> > out:
> >-	if (buf_out != NULL)
> >-		free(buf_out);
> > #ifdef USELZO
> > 	if (wrkmem != NULL)
> > 		free(wrkmem);
> >@@ -7227,51 +7458,47 @@ write_kdump_eraseinfo(struct cache_data
> > }
> >
> > int
> >-write_kdump_bitmap(void)
> >+write_kdump_bitmap(struct cache_data *cd)
> > {
> > 	struct cache_data bm;
> > 	long long buf_size;
> >-	off_t offset;
> >+	long write_size;
> >
> > 	int ret = FALSE;
> >
> > 	if (info->flag_elf_dumpfile)
> > 		return FALSE;
> >
> >+	/* set up to read bit map file in big blocks from the start */
> > 	bm.fd        = info->fd_bitmap;
> > 	bm.file_name = info->name_bitmap;
> > 	bm.offset    = 0;
> > 	bm.buf       = NULL;
> >-
> >-	if ((bm.buf = calloc(1, BUFSIZE_BITMAP)) == NULL) {
> >-		ERRMSG("Can't allocate memory for dump bitmap buffer. %s\n",
> >-		    strerror(errno));
> >-		goto out;
> >+	bm.cache_size = cd->cache_size;
> >+	bm.buf = cd->buf; /* use the bitmap cd */
> >+	/* using the dumpfile cd_bitmap buffer and fd */
> >+	if (lseek(cd->fd, info->offset_bitmap1, SEEK_SET) < 0) {
> >+		ERRMSG("Can't seek the dump file(%s). %s\n",
> >+		       info->name_memory, strerror(errno));
> >+		return FALSE;
> > 	}
> >-	offset = info->offset_bitmap1;
> > 	buf_size = info->len_bitmap;
> >-
> > 	while (buf_size > 0) {
> >-		if (buf_size >= BUFSIZE_BITMAP)
> >-			bm.cache_size = BUFSIZE_BITMAP;
> >-		else
> >-			bm.cache_size = buf_size;
> >-
> > 		if(!read_cache(&bm))
> > 			goto out;
> >-
> >-		if (!write_buffer(info->fd_dumpfile, offset,
> >-		    bm.buf, bm.cache_size, info->name_dumpfile))
> >-			goto out;
> >-
> >-		offset += bm.cache_size;
> >-		buf_size -= BUFSIZE_BITMAP;
> >+		write_size = cd->cache_size;
> >+		if (buf_size < cd->cache_size) {
> >+			write_size = buf_size;
> >+		}
> >+		if (write(cd->fd, cd->buf, write_size) != write_size) {
> >+			ERRMSG("Can't write a destination file. %s\n",
> >+				strerror(errno));
> >+			exit(1);
> >+		}
> >+		buf_size -= bm.cache_size;
> > 	}
> > 	ret = TRUE;
> > out:
> >-	if (bm.buf != NULL)
> >-		free(bm.buf);
> >-
> > 	return ret;
> > }
> >
> >@@ -8362,7 +8589,7 @@ int
> > writeout_dumpfile(void)
> > {
> > 	int ret = FALSE;
> >-	struct cache_data cd_header, cd_page;
> >+	struct cache_data cd_header, cd_page_descs, cd_page, cd_bitmap;
> >
> > 	info->flag_nospace = FALSE;
> >
> >@@ -8375,11 +8602,20 @@ writeout_dumpfile(void)
> > 	}
> > 	if (!prepare_cache_data(&cd_header))
> > 		return FALSE;
> >+	cd_header.offset = 0;
> >
> > 	if (!prepare_cache_data(&cd_page)) {
> > 		free_cache_data(&cd_header);
> > 		return FALSE;
> > 	}
> >+	if (!prepare_cache_data(&cd_page_descs)) {
> >+		free_cache_data(&cd_header);
> >+		free_cache_data(&cd_page);
> >+		return FALSE;
> >+	}
> >+	if (!prepare_cache_data(&cd_bitmap))
> >+		return FALSE;
> >+
> > 	if (info->flag_elf_dumpfile) {
> > 		if (!write_elf_header(&cd_header))
> > 			goto out;
> >@@ -8393,22 +8629,37 @@ writeout_dumpfile(void)
> > 		if (!write_elf_eraseinfo(&cd_header))
> > 			goto out;
> > 	} else if (info->flag_cyclic) {
> >-		if (!write_kdump_header())
> >+		if (!write_kdump_header(&cd_header))
> > 			goto out;
> >+		write_cache_flush(&cd_header);
> > 		if (!write_kdump_pages_and_bitmap_cyclic(&cd_header, &cd_page))
> > 			goto out;
> > 		if (!write_kdump_eraseinfo(&cd_page))
> > 			goto out;
> > 	} else {
> >-		if (!write_kdump_header())
> >-			goto out;
> >-		if (!write_kdump_bitmap())
> >-			goto out;
> >-		if (!write_kdump_pages(&cd_header, &cd_page))
> >-			goto out;
> >-		if (!write_kdump_eraseinfo(&cd_page))
> >-			goto out;
> >-	}
> >+		/*
> >+		 * Use cd_header for the caching operation up to the bit map.
> >+		 * Use cd_bitmap for 1-block (4096) operations on the bit map.
> >+		 * (it fits between the file header and page_desc's, both of
> >+		 *  which end and start on block boundaries)
> >+		 * Then use cd_page_descs and cd_page for page headers and
> >+		 * data (and eraseinfo).
> >+		 * Then back to cd_header to fill in the bitmap.
> >+		 */
> >+
> >+		if (!write_kdump_header(&cd_header))
> >+			goto out;
> >+		write_cache_flush(&cd_header);
> >+
> >+		if (!write_kdump_pages(&cd_page_descs, &cd_page))
> >+ 			goto out;
> >+ 		if (!write_kdump_eraseinfo(&cd_page))
> >+ 			goto out;
> >+
> >+		cd_bitmap.offset = info->offset_bitmap1;
> >+		if (!write_kdump_bitmap(&cd_bitmap))
> >+ 			goto out;
> >+ 	}
> > 	if (info->flag_flatten) {
> > 		if (!write_end_flat_header())
> > 			goto out;
> >@@ -8636,11 +8887,17 @@ create_dumpfile(void)
> > 		if (!get_elf_info(info->fd_memory, info->name_memory))
> > 			return FALSE;
> > 	}
> >+	blocksize = info->page_size;
> >+	if (!blocksize)
> >+		blocksize = sysconf(_SC_PAGE_SIZE);
> > 	if (!initial())
> > 		return FALSE;
> >
> > 	print_vtop();
> >
> >+	if (directioflag)
> >+		PROGRESS_MSG("Using O_DIRECT i/o for dump and bitmap.\n");
> >+
> > 	num_retry = 0;
> > retry:
> > 	if (info->flag_refiltering) {
> >@@ -9736,7 +9993,6 @@ int show_mem_usage(void)
> > 		return FALSE;
> > 	}
> >
> >-
> > 	if (!info->flag_cyclic)
> > 		info->flag_cyclic = TRUE;
> >
> >@@ -9795,6 +10051,7 @@ static struct option longopts[] = {
> > 	{"non-mmap", no_argument, NULL, OPT_NON_MMAP},
> > 	{"mem-usage", no_argument, NULL, OPT_MEM_USAGE},
> > 	{"splitblock-size", required_argument, NULL, OPT_SPLITBLOCK_SIZE},
> >+	{"directio", no_argument, NULL, OPT_DIRECT_IO},
> > 	{0, 0, 0, 0}
> > };
> >
> >@@ -9828,7 +10085,7 @@ main(int argc, char *argv[])
> >
> > 	info->block_order = DEFAULT_ORDER;
> > 	message_level = DEFAULT_MSG_LEVEL;
> >-	while ((opt = getopt_long(argc, argv, "b:cDd:EFfg:hi:lpRvXx:", longopts,
> >+	while ((opt = getopt_long(argc, argv, "b:cDd:EFfg:hi:jlpRvXx:", longopts,
> > 	    NULL)) != -1) {
> > 		switch (opt) {
> > 		case OPT_BLOCK_ORDER:
> >@@ -9872,6 +10129,10 @@ main(int argc, char *argv[])
> > 			info->flag_read_vmcoreinfo = 1;
> > 			info->name_vmcoreinfo = optarg;
> > 			break;
> >+		case OPT_DIRECT_IO:
> >+			directioflag = 1;
> >+			info->flag_cyclic = FALSE; // saving memory to avoid cyclic
> >+			break;
> > 		case OPT_DISKSET:
> > 			if (!sadump_add_diskset_info(optarg))
> > 				goto out;
> >
> >_______________________________________________
> >kexec mailing list
> >kexec at lists.infradead.org
> >http://lists.infradead.org/mailman/listinfo/kexec
> 
> _______________________________________________
> kexec mailing list
> kexec at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec

-- 
Cliff Wickman
SGI
cpw at sgi.com
(651)683-7524 vnet 207524
(651)482-9347 home



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