linux-ext4 - Re: After unlinking a large file on ext4, the process stalls for a long time

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Message-Id: <DE44CAD2-9FB4-4D46-A381-BFB00D39B607@dilger.ca>
Date:	Tue, 5 Aug 2014 23:54:35 +0200
From:	Andreas Dilger <adilger@...ger.ca>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Mason <mpeg.blue@...e.fr>,
	Lukáš Czerner <lczerner@...hat.com>,
	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: After unlinking a large file on ext4, the process stalls for a long time

On Aug 5, 2014, at 4:33, Theodore Ts'o <tytso@....edu> wrote:
> 
>> On Tue, Aug 05, 2014 at 12:55:14AM +0200, Andreas Dilger wrote:
>> It would be possible to optimize mb_free_blocks() by having it
>> clear a whole word at a time instead of a series if bits. 
> 
> It looks like we're doing this already in mb_test_and_clear_bits(),
> aren't we?

Sorry, I didn't see mb_test_and_clear_bits(), I was only looking at
mb_clear_bit() to see if it be the multi-bit optimization. 

>> I thought that was done already, but it doesn't appear to be the case.
>> Also, it isn't clear that the bit "normalization" is needed anymore.
>> This was done back in the aniceint times when the buddy bitmaps were stored on disk instead of being regenerated only at mount time. 
> 
> I'm not sure what you mean by this; the only reference I can find
> normalization is with normalizing requests?

I meant mb_correct_addr_and_bit(). 

Cheers, Andreas--
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