linux-ext4 - Re: [PATCH] resize2fs: radically reduce memory utilization by using rbtree bitmaps

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Date:	Fri, 25 Jul 2014 13:11:42 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	"Theodore Ts'o" <tytso@....edu>,
	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] resize2fs: radically reduce memory utilization by using
 rbtree bitmaps

On 7/25/14, 12:51 PM, Theodore Ts'o wrote:
> When resizing an empty 21T file system to 28T, resize2fs was using
> this much CPU time and memory:
> 
> 216.98user 19.77system 4:02.92elapsed 97%CPU (0avgtext+0avgdata 4485664maxresident)k
> 8inputs+1068680outputs (0major+800745minor)pagefaults 0swaps
> 
> After this one-line change:
> 
> 222.29user 0.49system 3:48.79elapsed 97%CPU (0avgtext+0avgdata 30080maxresident)k
> 8inputs+1068552outputs (0major+2497minor)pagefaults 0swaps
> 
> An extra 14 seconds (+6%) of elapsed time to reduce the memory
> utilization from 4.2GB to 29MB seems like a fair trade.  :-)

especially when it actually looks like 14 *fewer* seconds (-6%) ?

-Eric

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