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Date: Fri, 18 Dec 2009 21:15:22 +1100
From: Emil Mikulic <emikulic@gmail.com>
To: Alexander Zagrebin <alexz@visp.ru>
Message-ID: <20091218101522.GD71197@dmr.ath.cx>
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Cc: freebsd-current@freebsd.org
Subject: Re: ZFS and UFS on the same box. Cache memory allocation issue.
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On Fri, Dec 18, 2009 at 11:49:47AM +0300, Alexander Zagrebin wrote:
> As result UFS returns memory to "free" pool and ZFS can allocate it for ARC.
> It significantly increases ZFS performance.
> 
> Is there an another workaround?

I use: (cd /somefs && sudo umount /somefs)

The umount fails, but it does clear the buffer cache!  Memory reported
as "inactive" by top decreases.  I find this to be a really handy trick
when benchmarking I/O.  ;)

Unfortunately, it doesn't work on the root filesystem.

--Emil