From: Liu Bo <liubo2009@cn.fujitsu.com>
To: Martin <m_btrfs@ml1.co.uk>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: btrfs support for efficient SSD operation (data blocks alignment)
Date: Thu, 09 Feb 2012 09:42:21 +0800 [thread overview]
Message-ID: <4F33247D.2060305@cn.fujitsu.com> (raw)
In-Reply-To: <jgui4j$th5$1@dough.gmane.org>
On 02/09/2012 03:24 AM, Martin wrote:
> My understanding is that for x86 architecture systems, btrfs only allows
> a sector size of 4kB for a HDD/SSD. That is fine for the present HDDs
> assuming the partitions are aligned to a 4kB boundary for that device.
>
> However for SSDs...
>
> I'm using for example a 60GByte SSD that has:
>
> 8kB page size;
> 16kB logical to physical mapping chunk size;
> 2MB erase block size;
> 64MB cache.
>
> And the sector size reported to Linux 3.0 is the default 512 bytes!
>
>
> My first thought is to try formatting with a sector size of 16kB to
> align with the SSD logical mapping chunk size. This is to avoid SSD
> write amplification. Also, the data transfer performance for that device
> is near maximum for writes with a blocksize of 16kB and above. Yet,
> btrfs supports a 4kByte page/sector size only at present...
>
>
> Is there any control possible over the btrfs filesystem structure to map
> metadata and data structures to the underlying device boundaries?
>
> For example to maximise performance, can the data chunks and the data
> chunk size be aligned to be sympathetic to the SSD logical mapping chunk
> size and the erase block size?
>
The metadata buffer size will support size larger than 4K at least, it is on development.
> What features other than the trim function does btrfs employ to optimise
> for SSD operation?
>
e.g COW(avoid writing to one place multi-times),
delayed allocation(intend to reduce the write frequency)
thanks,
liubo
>
> Regards,
> Martin
>
>
> --
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next prev parent reply other threads:[~2012-02-09 1:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-08 19:24 btrfs support for efficient SSD operation (data blocks alignment) Martin
2012-02-09 1:42 ` Liu Bo [this message]
2012-02-10 1:05 ` Martin
2012-02-10 18:18 ` Martin Steigerwald
2012-05-01 17:04 ` Martin
2012-05-01 17:20 ` Hubert Kario
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