linux-kernel - Re: [PATCH 0/2] fs/ext4: increase parallelism in updating ext4 orphan list

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Message-ID: <524DFBB1.5010101@hp.com>
Date:	Thu, 03 Oct 2013 17:20:17 -0600
From:	Thavatchai Makphaibulchoke <thavatchai.makpahibulchoke@...com>
To:	Andreas Dilger <adilger@...ger.ca>
CC:	T Makphaibulchoke <tmac@...com>, Theodore Ts'o <tytso@....edu>,
	"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 0/2] fs/ext4: increase parallelism in updating ext4 orphan
 list

On 10/03/2013 06:28 PM, Andreas Dilger wrote:
> 
> It would also be possible to have a completely contention-free orphan
> inode list by only generating the on-disk orphan linked list in a
> pre-commit callback hook from an efficient in-memory list.  That would
> allow the common "add to orphan list; do something; remove from list"
> operations within a single transaction to run with minimal contention,
> and only the few rare cases of operations that exceed the lifetime of
> a single transaction would need to modify the on-disk list.
> 
> For example, a per-cpu list would be quite efficient, or a hash table.
> Then, a jbd2 callback run before the transaction commits could modify
> the requisite inodes and superblock.  All of those inodes are already
> (by definition) part of the transaction, so it won't add new buffers
> of the transaction.
> 
> I'm not necessarily against the current patch, just thinking aloud about
> how it might be improved further.
> 
> Cheers, Andreas
> 

Thanks again for the suggestion.  I'll rework this patch first and look into this possibility next.

Thanks,
Mak.


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