Mat
2010-Feb-10 18:15 UTC
[mount] commit intervall for metadata and btrfs - is it planned ?
Hi guys,
First off: you guys are doing amazing work !
btrfs "Better-FS" gets more and more stable, fast and space-efficient
than
all/most of the other filesystems :)
It being able to survive compiling of openoffice, chromium webbrowser and other
stressful stuff is a testament to its ever growing maturity
Now on to my question:
Since I''m using btrfs on more and more test-partitions on my system and
also am
into energy saving:
is the following mount-option which exists for reiserfs, ext2-4 and reiser4
(tmgr.atom_max_age) also planned to be implemented for btrfs ?
commit=nrsec
Sync all data and metadata every nrsec seconds. The default
value is 5 seconds. Zero means default.
(in this case ext3)
if yes, when will it be added ?
Many thanks in advance
Mat
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Josef Bacik
2010-Feb-10 18:55 UTC
Re: [mount] commit intervall for metadata and btrfs - is it planned ?
On Wed, Feb 10, 2010 at 06:15:26PM +0000, Mat wrote:> Hi guys, > > First off: you guys are doing amazing work ! > > btrfs "Better-FS" gets more and more stable, fast and space-efficient than > all/most of the other filesystems :) > > > It being able to survive compiling of openoffice, chromium webbrowser and other > stressful stuff is a testament to its ever growing maturity > > > Now on to my question: > > Since I''m using btrfs on more and more test-partitions on my system and also am > into energy saving: > > is the following mount-option which exists for reiserfs, ext2-4 and reiser4 > (tmgr.atom_max_age) also planned to be implemented for btrfs ? > > commit=nrsec > Sync all data and metadata every nrsec seconds. The default > value is 5 seconds. Zero means default. > > (in this case ext3) > > if yes, when will it be added ? > >It would be simple enough to do, but keep in mind that btrfs doesnt act like ext2/3 does, so the commit doesn''t necessarily mean _all_ data will go down to disk, just data thats been allocated and writeout has been started on, which is mostly controlled by the vm''s dirty writeback stuff or if the apps you use have been using fsync(). Any metadata thats been dirtied will be sync''ed every 30 seconds. Doing much more than that is just widening the window for you to lose new files and stuff (again, if they''ve not been fsync()''ed). Personally 30 seconds is a good balance between being safe and saving battery life, but I''m sure at some point we''ll expose the commit interval via a mount option. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Mat
2010-Feb-23 12:49 UTC
Re: [mount] commit intervall for metadata and btrfs - is it planned ?
On Wed, Feb 10, 2010 at 7:55 PM, Josef Bacik <josef@redhat.com> wrote:> On Wed, Feb 10, 2010 at 06:15:26PM +0000, Mat wrote: >> Hi guys, >> >> First off: you guys are doing amazing work ! >> >> btrfs "Better-FS" gets more and more stable, fast and space-efficient than >> all/most of the other filesystems :) >> >> >> It being able to survive compiling of openoffice, chromium webbrowser and other >> stressful stuff is a testament to its ever growing maturity >> >> >> Now on to my question: >> >> Since I''m using btrfs on more and more test-partitions on my system and also am >> into energy saving: >> >> is the following mount-option which exists for reiserfs, ext2-4 and reiser4 >> (tmgr.atom_max_age) also planned to be implemented for btrfs ? >> >> commit=nrsec >> Sync all data and metadata every nrsec seconds. The default >> value is 5 seconds. Zero means default. >> >> (in this case ext3) >> >> if yes, when will it be added ? >> >> > > It would be simple enough to do, but keep in mind that btrfs doesnt act like > ext2/3 does, so the commit doesn''t necessarily mean _all_ data will go down to > disk, just data thats been allocated and writeout has been started on, which is > mostly controlled by the vm''s dirty writeback stuff or if the apps you use have > been using fsync(). Any metadata thats been dirtied will be sync''ed every 30 > seconds. Doing much more than that is just widening the window for you to lose > new files and stuff (again, if they''ve not been fsync()''ed). Personally 30 > seconds is a good balance between being safe and saving battery life, but I''m > sure at some point we''ll expose the commit interval via a mount option. Thanks, > > Josef >Thanks for your answer Josef ! I''ll tweak /proc/sys/vm/dirty_writeback_centisecs, the other /proc/sys/vm/dirty* knobs for now and stick to the limit of 30 seconds Regards Mat -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html