From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gordan Bobic <gordan@bobich.net>
Subject: Re: SSD Optimizations
Date: Thu, 11 Mar 2010 12:03:42 +0000
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On Thu, 11 Mar 2010 10:35:45 +0000, Daniel J Blueman
<daniel.blueman@gmail.com> wrote:
>>>> [...]
>>>> Are there similar optimizations available in BTRFS?
>>>
>>> There is an SSD mount option available[1].
>>>
>>> [1]
http://btrfs.wiki.kernel.org/index.php/Getting_started#Mount_Options
>>
>> But what _exactly_ does it do?
> 
> Chris explains the change to favour spatial locality in allocator
> behaviour in with '-o ssd'. '-o ssd_spread' does the opposite, where
> RMW cycles are higher penalty. Elsewhere IIRC, Chris also said BTRFS
> attempts to submit 128KB BIOs where possible (or wishful thinking?):
> 
> http://markmail.org/message/4sq4uco2lghgxzzz

Thanks, that's useful info.

What about FS block and metadata alignment, though? Is there a way to
leverage the knowledge of erase block size in order to reduce wear and
increase performance?

Gordan