[MAKDUMPFILE PATCH] Add option to estimate the size of vmcore dump files
Bhupesh Sharma
bhsharma at redhat.com
Tue Oct 13 05:27:03 EDT 2020
Hello Julien,
Thanks for the patch. Some nitpicks inline:
On Mon, Oct 12, 2020 at 12:39 PM Julien Thierry <jthierry at redhat.com> wrote:
>
> A user might want to know how much space a vmcore file will take on
> the system and how much space on their disk should be available to
> save it during a crash.
>
> The option --vmcore-size does not create the vmcore file but provides
> an estimation of the size of the final vmcore file created with the
> same make dumpfile options.
>
> Signed-off-by: Julien Thierry <jthierry at redhat.com>
> Cc: Kazuhito Hagio <k-hagio-ab at nec.com>
> ---
> makedumpfile.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++--
> makedumpfile.h | 12 +++++++
> print_info.c | 4 +++
> 3 files changed, 111 insertions(+), 3 deletions(-)
Please update 'makedumpfile.8' as well in v2, so that the man page can
document the newly added option and how to use it to determine the
vmcore-size.
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 4c4251e..0a2bfba 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -26,6 +26,7 @@
> #include <limits.h>
> #include <assert.h>
> #include <zlib.h>
> +#include <libgen.h>
I know we don't follow alphabetical order for include files in
makedumpfile code, but it would be good to place the new - ones
accordingly. So <libgen.h> can go with <limits.h> here.
> struct symbol_table symbol_table;
> struct size_table size_table;
> @@ -1366,7 +1367,25 @@ open_dump_file(void)
> if (!info->flag_force)
> open_flags |= O_EXCL;
>
> - if (info->flag_flatten) {
> + if (info->flag_vmcore_size) {
> + char *namecpy;
> + struct stat statbuf;
> + int res;
> +
> + namecpy = strdup(info->name_dumpfile ?
> + info->name_dumpfile : ".");
> +
> + res = stat(dirname(namecpy), &statbuf);
> + free(namecpy);
> + if (res != 0)
> + return FALSE;
> +
> + fd = -1;
> + info->dumpsize_info.blksize = statbuf.st_blksize;
> + info->dumpsize_info.block_buff_size = BASE_NUM_BLOCKS;
> + info->dumpsize_info.block_info = calloc(BASE_NUM_BLOCKS, 1);
> + info->dumpsize_info.non_hole_blocks = 0;
> + } else if (info->flag_flatten) {
> fd = STDOUT_FILENO;
> info->name_dumpfile = filename_stdout;
> } else if ((fd = open(info->name_dumpfile, open_flags,
> @@ -1384,6 +1403,9 @@ check_dump_file(const char *path)
> {
> char *err_str;
>
> + if (info->flag_vmcore_size)
> + return TRUE;
> +
> if (access(path, F_OK) != 0)
> return TRUE; /* File does not exist */
> if (info->flag_force) {
> @@ -4622,6 +4644,47 @@ write_and_check_space(int fd, void *buf, size_t buf_size, char *file_name)
> return TRUE;
> }
>
> +static int
> +write_buffer_update_size_info(off_t offset, void *buf, size_t buf_size)
> +{
> + struct dumpsize_info *dumpsize_info = &info->dumpsize_info;
> + int blk_end_idx = (offset + buf_size - 1) / dumpsize_info->blksize;
> + int i;
> +
> + /* Need to grow the dumpsize block buffer? */
> + if (blk_end_idx >= dumpsize_info->block_buff_size) {
> + int alloc_size = MAX(blk_end_idx - dumpsize_info->block_buff_size, BASE_NUM_BLOCKS);
> +
> + dumpsize_info->block_info = realloc(dumpsize_info->block_info,
> + dumpsize_info->block_buff_size + alloc_size);
> + if (!dumpsize_info->block_info) {
> + ERRMSG("Not enough memory\n");
> + return FALSE;
> + }
> +
> + memset(dumpsize_info->block_info + dumpsize_info->block_buff_size,
> + 0, alloc_size);
> + dumpsize_info->block_buff_size += alloc_size;
> + }
> +
> + for (i = 0; i < buf_size; ++i) {
> + int blk_idx = (offset + i) / dumpsize_info->blksize;
> +
> + if (dumpsize_info->block_info[blk_idx]) {
> + i += dumpsize_info->blksize;
> + i = i - (i % dumpsize_info->blksize) - 1;
> + continue;
> + }
> +
> + if (((char *) buf)[i] != 0) {
> + dumpsize_info->non_hole_blocks++;
> + dumpsize_info->block_info[blk_idx] = 1;
> + }
> + }
> +
> + return TRUE;
> +}
> +
> int
> write_buffer(int fd, off_t offset, void *buf, size_t buf_size, char *file_name)
> {
> @@ -4643,6 +4706,8 @@ write_buffer(int fd, off_t offset, void *buf, size_t buf_size, char *file_name)
> }
> if (!write_and_check_space(fd, &fdh, sizeof(fdh), file_name))
> return FALSE;
> + } else if (info->flag_vmcore_size && fd == info->fd_dumpfile) {
> + return write_buffer_update_size_info(offset, buf, buf_size);
> } else {
> if (lseek(fd, offset, SEEK_SET) == failed) {
> ERRMSG("Can't seek the dump file(%s). %s\n",
> @@ -9018,6 +9083,12 @@ close_dump_file(void)
> if (info->flag_flatten)
> return;
>
> + if (info->flag_vmcore_size && info->fd_dumpfile == -1) {
> + free(info->dumpsize_info.block_info);
> + info->dumpsize_info.block_info = NULL;
> + return;
> + }
> +
> if (close(info->fd_dumpfile) < 0)
> ERRMSG("Can't close the dump file(%s). %s\n",
> info->name_dumpfile, strerror(errno));
> @@ -10963,6 +11034,12 @@ check_param_for_creating_dumpfile(int argc, char *argv[])
> if (info->flag_flatten && info->flag_split)
> return FALSE;
>
> + if (info->flag_flatten && info->flag_vmcore_size)
> + return FALSE;
> +
> + if (info->flag_mem_usage && info->flag_vmcore_size)
> + return FALSE;
> +
> if (info->name_filterconfig && !info->name_vmlinux)
> return FALSE;
>
> @@ -11043,7 +11120,8 @@ check_param_for_creating_dumpfile(int argc, char *argv[])
> */
> info->name_memory = argv[optind];
>
> - } else if ((argc == optind + 1) && info->flag_mem_usage) {
> + } else if ((argc == optind + 1) && (info->flag_mem_usage ||
> + info->flag_vmcore_size)) {
> /*
> * Parameter for showing the page number of memory
> * in different use from.
> @@ -11423,6 +11501,7 @@ static struct option longopts[] = {
> {"work-dir", required_argument, NULL, OPT_WORKING_DIR},
> {"num-threads", required_argument, NULL, OPT_NUM_THREADS},
> {"check-params", no_argument, NULL, OPT_CHECK_PARAMS},
> + {"vmcore-size", no_argument, NULL, OPT_VMCORE_SIZE},
> {0, 0, 0, 0}
> };
>
> @@ -11589,6 +11668,9 @@ main(int argc, char *argv[])
> info->flag_check_params = TRUE;
> message_level = DEFAULT_MSG_LEVEL;
> break;
> + case OPT_VMCORE_SIZE:
> + info->flag_vmcore_size = TRUE;
> + break;
> case '?':
> MSG("Commandline parameter is invalid.\n");
> MSG("Try `makedumpfile --help' for more information.\n");
> @@ -11598,6 +11680,10 @@ main(int argc, char *argv[])
> if (flag_debug)
> message_level |= ML_PRINT_DEBUG_MSG;
>
> + if (info->flag_vmcore_size)
> + /* Suppress progress indicator as dumpfile won't get written */
> + message_level &= ~ML_PRINT_PROGRESS;
> +
> if (info->flag_check_params)
> /* suppress debugging messages */
> message_level = DEFAULT_MSG_LEVEL;
> @@ -11751,7 +11837,11 @@ main(int argc, char *argv[])
> goto out;
>
> MSG("\n");
> - if (info->flag_split) {
> +
> + if (info->flag_vmcore_size) {
> + MSG("Estimated size to save vmcore is: %lld Bytes\n",
> + (long long)info->dumpsize_info.non_hole_blocks * info->dumpsize_info.blksize);
> + } else if (info->flag_split) {
> MSG("The dumpfiles are saved to ");
> for (i = 0; i < info->num_dumpfile; i++) {
> if (i != (info->num_dumpfile - 1))
> @@ -11808,6 +11898,8 @@ out:
> free(info->page_buf);
> if (info->parallel_info != NULL)
> free(info->parallel_info);
> + if (info->dumpsize_info.block_info != NULL)
> + free(info->dumpsize_info.block_info);
> free(info);
>
> if (splitblock) {
> diff --git a/makedumpfile.h b/makedumpfile.h
> index 03fb4ce..fd78d5f 100644
> --- a/makedumpfile.h
> +++ b/makedumpfile.h
> @@ -1277,6 +1277,15 @@ struct parallel_info {
> #endif
> };
>
> +#define BASE_NUM_BLOCKS 50
> +
> +struct dumpsize_info {
> + int blksize;
> + int block_buff_size;
> + unsigned char *block_info;
> + int non_hole_blocks;
> +};
> +
> struct ppc64_vmemmap {
> unsigned long phys;
> unsigned long virt;
> @@ -1321,6 +1330,7 @@ struct DumpInfo {
> int flag_vmemmap; /* kernel supports vmemmap address space */
> int flag_excludevm; /* -e - excluding unused vmemmap pages */
> int flag_use_count; /* _refcount is named _count in struct page */
> + int flag_vmcore_size; /* estimate the size of the vmcore file instead of creating it */
> unsigned long vaddr_for_vtop; /* virtual address for debugging */
> long page_size; /* size of page */
> long page_shift;
> @@ -1425,6 +1435,7 @@ struct DumpInfo {
> int num_dumpfile;
> struct splitting_info *splitting_info;
> struct parallel_info *parallel_info;
> + struct dumpsize_info dumpsize_info;
>
> /*
> * bitmap info:
> @@ -2364,6 +2375,7 @@ struct elf_prstatus {
> #define OPT_NUM_THREADS OPT_START+16
> #define OPT_PARTIAL_DMESG OPT_START+17
> #define OPT_CHECK_PARAMS OPT_START+18
> +#define OPT_VMCORE_SIZE OPT_START+19
>
> /*
> * Function Prototype.
> diff --git a/print_info.c b/print_info.c
> index e0c38b4..6f5a165 100644
> --- a/print_info.c
> +++ b/print_info.c
> @@ -308,6 +308,10 @@ print_usage(void)
> MSG(" the crashkernel range, then calculates the page number of different kind per\n");
> MSG(" vmcoreinfo. So currently /proc/kcore need be specified explicitly.\n");
> MSG("\n");
> + MSG(" [--vmcore-size]:\n");
> + MSG(" This option provides an estimation of the size needed to save VMCORE on disk.\n");
> + MSG(" This option option cannot be used in combination with -F.\n");
Also not in combination with --mem-usage (as per the code changes above)?
And may be the options '--mem-usage / -F' also need an update to
mention they can't be used with --vmcore-size option.
> + MSG("\n");
> MSG(" [-D]:\n");
> MSG(" Print debugging message.\n");
> MSG("\n");
> --
I like the idea, but sometimes we use makedumpfile to generate a
dumpfile in the primary kernel as well. For example:
$ makedumpfile -d 31 -x vmlinux /proc/kcore dumpfile
In such use-cases it is useful to use --vmcore-size and still generate
the dumpfile (right now the default behaviour is not to generate a
dumpfile when --vmcore-size is specified). Maybe we need to think more
on supporting this use-case as well.
Regards,
Bhupesh
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