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From: "Hans J. Koch" <hjk@linutronix.de>
To: linux-mtd@lists.infradead.org
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Adrian Hunter <adrian.hunter@nokia.com>,
	Artem Bityutskiy <dedekind1@gmail.com>
Subject: ubifs: sync() causes writes even if nothing is changed
Date: Wed, 13 Oct 2010 18:30:05 +0200	[thread overview]
Message-ID: <20101013163005.GB1889@silverbox.local> (raw)

Running this command:

# while true ; do sync; sleep 1; done

causes two eraseblocks being erased every second, although there
are no writes to the ubifs filesystem. I hacked some printks into
my NAND driver that print page_address and column for each erase.
With that, I get this output every second:

...
[   63.701765] erase p=0x0000ae40 c=0xffffffff
[   63.706534] erase p=0xffffffff c=0xffffffff
[   63.725492] erase p=0x0000ae80 c=0xffffffff
[   63.730260] erase p=0xffffffff c=0xffffffff
...

>From a quick glance at the ubifs code, this might come out of the
garbage collector that is triggered on every sync() and writes
something even if nothing has changed.

Is that really needed?

Thanks,
Hans

             reply	other threads:[~2010-10-13 16:28 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-13 16:30 Hans J. Koch [this message]
2010-10-15  6:13 ` ubifs: sync() causes writes even if nothing is changed Artem Bityutskiy
2010-10-20 13:26 ` Artem Bityutskiy
2010-10-21  8:23   ` Sebastian Andrzej Siewior
2010-10-21  8:32     ` Artem Bityutskiy
2010-10-21 17:04       ` Matthieu CASTET
2010-10-21 18:43         ` Artem Bityutskiy
2011-01-16 17:48 ` Artem Bityutskiy
2011-01-17  8:19   ` Adrian Hunter
2011-01-17  9:04     ` Artem Bityutskiy
2011-01-17 21:52     ` Artem Bityutskiy
2011-01-17 21:53     ` [PATCH v2 1/3] UBIFS: re-arrange variables in ubifs_info Artem Bityutskiy
2011-01-17 21:54       ` [PATCH v2 2/3] UBIFS: introduce mounting flag Artem Bityutskiy
2011-01-18  7:30     ` [PATCH v2 3/3] UBIFS: do not start the commit if there is nothing to commit Artem Bityutskiy
2011-01-18  7:36       ` Artem Bityutskiy
2011-01-18 12:29         ` John Ogness
2011-01-21 11:13           ` Artem Bityutskiy
2011-01-21 11:28             ` John Ogness
2011-01-25  8:20               ` Artem Bityutskiy

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