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Date: Thu, 27 Apr 2006 15:47:37 -0400
From: Mike Jakubik <mikej@rogers.com>
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To: Bartosz Fabianowski <freebsd@chillt.de>
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Cc: "ml@sd2i.com" <ml@sd2i.com>, freebsd-stable@freebsd.org
Subject: Re: RELENG_4 -> 5 -> 6: significant performance regression
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Bartosz Fabianowski wrote:
>> You wrote that Giant is needed in 6.0 and now you write it has been
>> removed.
>
> In 4.x, every UFS write requires the Giant lock. In 6.x, Giant is not 
> normally required, making file system operations faster. When you 
> enable QUOTA, you basically get back to the 4.x behavior where Giant 
> is needed for each write. This is why in 6.x UFS will normally be 
> faster but if you enable QUOTA, you lose the newly gained performance 
> again.

Why isn't QUOTA mpsafe then?