Re: Is the checkpoint interval adjustable?

["Mike Audia" <mikey_a@gmx.com>]

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> On Wed, Jul 31, 2013 at 04:02:29PM -0400, Mike Audia wrote:
> > I believe 30 sec is the default for the checkpoint interval.  Is this adjustable?
>
> It doesn't look like it. It looks like it's implemented with raw '30's
> in the code.
>
>  delay = HZ * 30;
> ...
>  (now < cur->start_time || now - cur->start_time <
> 30)) {
>
> If you want more frequent forced commits you could always syncfs()
> regularly from userspace, I suppose.

Thank you kindly for the prompt reply.  My goal is to make them _less_ frequent.  I am NO programmer by any stretch.  Let's say I want them to be once every 5 min (300 sec).  Is the attached patch sane to acheive this?  Are there any unforeseen and effects of doing this?  Thank you for the consideration.

[-- Attachment #2: Attachment: 10_minute_checkpoints.patch --]
[-- Type: text/x-patch, Size: 604 bytes --]

--- a/fs/btrfs/disk-io.c	2013-07-31 18:05:22.581062955 -0400
+++ b/fs/btrfs/disk-io.c	2013-07-31 18:06:15.243201652 -0400
@@ -1713,7 +1713,7 @@
 
 	do {
 		cannot_commit = false;
-		delay = HZ * 30;
+		delay = HZ * 300;
 		mutex_lock(&root->fs_info->transaction_kthread_mutex);
 
 		spin_lock(&root->fs_info->trans_lock);
@@ -1725,7 +1725,7 @@
 
 		now = get_seconds();
 		if (!cur->blocked &&
-		    (now < cur->start_time || now - cur->start_time < 30)) {
+		    (now < cur->start_time || now - cur->start_time < 300)) {
 			spin_unlock(&root->fs_info->trans_lock);
 			delay = HZ * 5;
 			goto sleep;