From: Chao Yu <chao2.yu@samsung.com>
To: "'Jaegeuk Kim'" <jaegeuk@kernel.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
References: <001201cf87c6$92b9fad0$b82df070$@samsung.com>
In-reply-to: <001201cf87c6$92b9fad0$b82df070$@samsung.com>
Subject: RE: [f2fs-dev] [PATCH] f2fs: refactor flush_nat_entries codes for
 reducing NAT writes
Date: Tue, 17 Jun 2014 10:33:12 +0800
Message-id: <002301cf89d4$97aaf7f0$c700e7d0$@samsung.com>
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Sender: linux-kernel-owner@vger.kernel.org

Hi all,

There are problem in this patch, please ignore this patch, sorry for the noise.
I will resend later.

> -----Original Message-----
> From: Chao Yu [mailto:chao2.yu@samsung.com]
> Sent: Saturday, June 14, 2014 7:48 PM
> To: Jaegeuk Kim
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Subject: [f2fs-dev] [PATCH] f2fs: refactor flush_nat_entries codes for reducing NAT writes
> 
> Although building NAT journal in cursum reduce the read/write work for NAT
> block, but previous design leave us lower performance when write checkpoint
> frequently for these cases:
> 1. if journal in cursum has already full, it's a bit of waste that we flush all
>    nat entries to page for persistence, but not to cache any entries.
> 2. if journal in cursum is not full, we fill nat entries to journal util
>    journal is full, then flush the left dirty entries to disk without merge
>    journaled entries, so these journaled entries may be flushed to disk at next
>    checkpoint but lost chance to flushed last time.
> 
> In this patch we merge dirty entries located in same NAT block to nat entry set,
> and linked all set to list, sorted ascending order by entries' count of set.
> Later we flush entries in sparse set into journal as many as we can, and then
> flush merged entries to disk.
> 


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