List, Tomo, Please find attached a trivial patch for tgtimg. It changes to use posix_fallocate() when creating raw disk images instead of using a loop with pwrite(). This makes it less intrusive to the system when creating many large disk images at the same time. I did try using posix_fadvise() as an alternative but that did not work well. (it did not have much effect on the vm trashing) regards ronnie sahlberg
From 1a3ab72cac0110d5463a4460db3c02521334d528 Mon Sep 17 00:00:00 2001
From: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
Date: Tue, 12 Oct 2010 14:22:50 +1100
Subject: [PATCH] Use posix_fallocate() to create the disk image file instead
of writing the data.
This plays nicer with the vm system.
Signed-off-by: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
---
usr/tgtimg.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/usr/tgtimg.c b/usr/tgtimg.c
index 758f1fb..169207a 100644
--- a/usr/tgtimg.c
+++ b/usr/tgtimg.c
@@ -19,6 +19,7 @@
*
*/
+#define _XOPEN_SOURCE 600
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
@@ -416,10 +417,9 @@ static int mmc_ops(int op, char *path, char *media_type)
static int sbc_new(int op, char *path, char *capacity, char *media_type)
{
int fd;
- ssize_t ignored;
if (!strncasecmp("disk", media_type, 4)) {
- uint32_t pos, size;
+ uint32_t size;
char *buf;
sscanf(capacity, "%d", &size);
@@ -438,9 +438,10 @@ static int sbc_new(int op, char *path, char *capacity, char *media_type)
perror("Failed creating file");
exit(2);
}
-
- for (pos = 0; pos < size; pos++)
- ignored = pwrite(fd, buf, 1024*1024, pos*1024*1024LL);
+ if (posix_fallocate(fd, 0, size*1024*1024LL) == -1) {
+ perror("posix_fallocate failed.");
+ exit(3);
+ }
free(buf);
close(fd);
--
1.7.3.1
Attachment:
0001-Use-posix_fallocate-to-create-the-disk-image-file-in.patch.gz
Description: GNU Zip compressed data
