Re: Deadlocks! help, please!

[Ryusuke Konishi <ryusuke-sG5X7nlA6pw@public.gmane.org>]

Hi Gábor,

On Thu, 2008-02-07 at 11:09 +0100, Gergely Gábor wrote:
> I have installed it (with some other patches: the one for the mount option bug, 
> and other for udivdi (that is needed to link the module properly at me) and 
> started a download in rtorrent for the night. It has not ferrzed, but i have 
> experianced massive memory leaks, either on the cleaner, or int he module.
>  now i'm trying to reproduce the bug with fs running without cleaner. 
> if it will not arise in a day, i'll try the cleaner as well. 
> I have a question about the cleaner, that might help my find the bug:
>  can I send a signal to the cleaner to finish and commit unfinished changes and
> and can I manually start a cleaner (possibly with valgrind)?

Yes, you can manually start and shutdown the cleaner.

> Can I send signals to pause cleaning (for example I go on battery), and to resume?

No, the cleaner doesn't support pause/resume by signal, however 
you can do the same thing by the manual shutdown and restart.

> This leak error ate up all my memory, and forced all apps to swap, slowing the
>  system down so much, that it took almost an hour to exit rtorrent...
> unfortunalety i forgot to vmstat after the kill of the cleaner, before 
> umounting the fs. If I kill the fs will it not leave garbage (i mean badly formed
> entries in the log) after itself if it will, will those entries be cleaned up? 

Yes, they will.  NILFS is designed not to leave garbage.
However, the NILFS module holds memory for b-tree pages globally, so it
may eat some memory even after umount.

> after i umounted the partition, i had my ram back cleanly (i'd say that this 
> was possibly the cleaner, as the module was left in memory even after the umount,
>  still the ram wasn't wasted...) Is that possible, that the ram was not wasted, 
> but the cleaner/fs is bit inefficient, or can't be made simpler, and I should 
> buy more ram? it ate ~440Mb of memory. (i have 512Mb)

OK, I will review the patch to find out an elemental leak bug.
For now, the latest (unpublished) version seems to work properly 
in my environment.

We will soon release nilfs-2.0.0.
I'd like to clean things up with the release.
Since we don't want -testing release anymore, we may release it
even if the problem ramains.
If I can find the leak bug in time, I will include it in the release.

> Otherwise the patch seems to work cleanly I haven't applied the
> previous patch 
> you proposed, should I have tried? (it gave errors)

You don't have to apply the previous patch;  the new patch includes the
previous change.

> Possibly if you set up a git/hg/other repo, life'd be more convinient.
> they made my life simpler even in my small school projects.

Sorry for inconvenience.
We also have a plan to make a git (or other kind of) repository
after it gets settled.  So please wait a little longer.

Best regards,
-- 
Ryusuke Konishi
NILFS team NTT
http://www.nilfs.org/