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Date:      Tue, 16 Dec 2008 09:16:52 -0700
From:      Scott Long <scottl@samsco.org>
To:        Alexander Motin <mav@FreeBSD.org>
Cc:        svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org
Subject:   Re: svn commit: r186182 - head/sys/dev/ata
Message-ID:  <4947D474.9040802@samsco.org>
In-Reply-To: <200812161604.mBGG4fBd041647@svn.freebsd.org>
References:  <200812161604.mBGG4fBd041647@svn.freebsd.org>

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Alexander Motin wrote:
> Author: mav
> Date: Tue Dec 16 16:04:40 2008
> New Revision: 186182
> URL: http://svn.freebsd.org/changeset/base/186182
> 
> Log:
>   Call ata_legacy() only once on attach and save it's result. Scanning PCI
>   configuration registers (which are not going to change) on every interrupt
>   looks expensive, especially when interrupt is shared. Profiling shows me 3%
>   of time spent by atapci0 on pure network load due to IRQ sharing with em0.
> 

Nice change.  PCI Config registers are exceptionally slow to access on 
most systems.

Scott




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