some notes on a memory leak

From: "Gergely Gábor" <elentirmo.gilgalad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: users-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org
Subject: some notes on a memory leak
Date: Thu, 14 Feb 2008 01:02:58 +0100	[thread overview]
Message-ID: <20080214010258.76494d68@vosztok> (raw)

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Hello Ryusuke, and other nilfs developers, and users!

I have left my computer working, testing nilfs. I have found that after a log period of time, most of the memory in the computer vas allocated as cache (according to vmstat) and even aftel killing all processes that held files open, the amount (~430 megabytes) did not decrease significantly. I have unmounted the filesystem, and most cache was freed up, and after remounting nilfs, the system was fast as lightning again (the module was not needed to be removed to reclaim the memory). This leads to the assumption, that some data is left cached, even when not in use. To reproduce this behaviour, I simply started "vmstat 1", and rtorrent, started a download, and watched the cache consumption climb. after exiting rtorrent, most of the cache is not reclaimed, not even after a long period of time. (i understand, that leaving blocks in the cache is preferable for a log structured fs, as that reduces seeks necessary for reading, but possibly some aging mechanism, and/or a maximum cache size option would be a good idea to implement in the future, if not yet done)

Apart from this minor issue, the fs is working fine. i feel that (but this is very subjective, only based on my perception) the current rate of this leakage is far smaller that the rate i experienced with the patched version of testing-8. (than the system went unusable after a few minutes, as all mem was consumed, not it took more than 4 hours, as i wrote a letter with fairly much free mem before leaving home with the machine running.)

Sorry for flooding the mail list with my self-contradictory status reports.

Please tell me, where can i read about the architecture of nilfs2 in greater detail, other than the code? (i'm willing to understand the code as well, but i'd need some guidance, where to start. I'd be the most happy if i could provide some more useful help rather than constant "complaining") has many things changed since nilfs1? (i have found papers about that on the project homepage)

Yours sincerely: Gergely Gábor
-- 
Gergely Gábor <elentirmo.gilgalad-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

* random fortune:
Rome wasn't burnt in a day.

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