linux-kernel - Re: [PATCH 1/2] fs/ext4: adding and initalizing new members of ext4_inode_info and ext4_sb

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Message-ID: <524DFA56.6000708@hp.com>
Date:	Thu, 03 Oct 2013 17:14:30 -0600
From:	Thavatchai Makphaibulchoke <thavatchai.makpahibulchoke@...com>
To:	Andreas Dilger <adilger@...ger.ca>
CC:	T Makphaibulchoke <tmac@...com>, Theodore Ts'o <tytso@....edu>,
	adilger.kernel@...ger.ca,
	"linux-ext4@...r.kernel.org List" <linux-ext4@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	aswin@...com
Subject: Re: [PATCH 1/2] fs/ext4: adding and initalizing new members of ext4_inode_info
 and ext4_sb_info

On 10/03/2013 06:37 PM, Andreas Dilger wrote:
> On 2013-10-02, at 9:36 AM, T Makphaibulchoke wrote:
> 
> What do these additional fields do to the size of struct ext4_inode_info?
> I recall that Ted did a bunch of work to shrink this enough to fit nicely
> into a slab, and it would be a shame to increase the inode size to overflow
> the current packing and increase per-inode memory usage by 25-33%, for an
> improvement that is only noticeable on a 90-core machine.
> 
> Is there another lock that could be shared for this that is unlikely to
> cause much contention?

Thanks for the suggestion.  I was also thinking about this earlier, not sure if it's a good practice.  Looks like it is way better than increasing the inode size.  Will look into this in my rework.
 
> 
> Also, it isn't clear to me why this patch is separate from 2/2, because
> all it does is add fields that are not used for anything.  I don't think
> the 8 lines of code here are so complex that they can't be part of the
> same patch that is actually using them.
> 
> Cheers, Andreas
> 

I was debating whether to combine them into 1 or make them 2 patches.  I'll combine them into one patch in my next submittal.

Thanks,
Mak.

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