Hi,
On Saturday, 11 August 2007 00:32, Couriousous wrote:
> Hello
>
> Here is an easy way to speed up the image writing. It simply tell the kernel
> to
> immediatly start writing the data to disk asynchronously and not to do the
> traditional
> buffering.
>
> Mesurement:
> System: pentium D820, Harddisk ~58Mo/s, image size 500Mo
> Time of suspend to disk, average of 3 run.
>
> Compression enabled:
> Without patch: 35 sec.
> With patch: 27 sec.
> Speedup: 22%
>
> Compression disabled:
> Without patch: 17 sec.
> With patch: 14 sec.
> Speedup: 18%
OK, thanks.
Still, I think we should only sync if we have called write(), no?
---
suspend.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
Index: suspend/suspend.c
===================================================================
--- suspend.orig/suspend.c
+++ suspend/suspend.c
@@ -236,8 +236,12 @@ static int write_area(int fd, void *buf,
ssize_t cnt = 0;
if (offset) {
- if (lseek64(fd, offset, SEEK_SET) == offset)
+ if (lseek64(fd, offset, SEEK_SET) == offset) {
cnt = write(fd, buf, size);
+ /* Ask kernel to immediatly start writing the data */
+ sync_file_range(fd, offset, size,
+ SYNC_FILE_RANGE_WRITE);
+ }
if (cnt == size)
res = 0;
else
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