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Date: Sun, 7 Nov 2004 23:37:26 +0800 (CST)
From: Wei-Kai Wu <wkwu@csie.nctu.edu.tw>
Reply-To: Wei-Kai Wu <wkwu@csie.nctu.edu.tw>
To: FreeBSD-gnats-submit@freebsd.org
Cc:
Subject: More AHC_ALLOW_MEMIO
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>Number:         73642
>Category:       kern
>Synopsis:       More AHC_ALLOW_MEMIO
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    gibbs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Nov 07 15:40:27 GMT 2004
>Closed-Date:    Sun Nov 07 16:53:59 GMT 2004
>Last-Modified:  Sun Nov 07 16:53:59 GMT 2004
>Originator:     Wei-Kai Wu
>Release:        FreeBSD 4.10-STABLE i386
>Organization:
Kavalan
>Environment:
System: FreeBSD 4.X-Series , 5.X-Series
>Description:
The adaptec SCSI controller such as Aic7892 (29160 SCSI adapter) uses "ahc"
driver which has an option "AHC_ALLOW_MEMIO".
The AHC_ALLOW_MEMIO enhances the I/O performance a lot compared with those 
SCSI drivers have no MEMIO option.
I have tried Adaptec AIC7902 Ultra320 SCSI adapter (which has no MEMIO option),
and the performance is really bad compared with Aic7892 MEMIO option.
I doubt why there is no MEMIO option for other SCSI controllers?
>How-To-Repeat:
>Fix:
>Release-Note:
>Audit-Trail:
Responsible-Changed-From-To: freebsd-advocacy->gibbs 
Responsible-Changed-By: delphij 
Responsible-Changed-When: Sun Nov 7 15:47:52 GMT 2004 
Responsible-Changed-Why:  
Over to ahc/ahd maintainer 

http://www.freebsd.org/cgi/query-pr.cgi?pr=73642 
State-Changed-From-To: open->closed 
State-Changed-By: gibbs 
State-Changed-When: Sun Nov 7 16:47:51 GMT 2004 
State-Changed-Why:  
The AHC_ALLOW_MEMIO option was introduced at a time when the driver did 
not have a robust method for detecting a failure when memory mapping 
controller registers on some "cheap" x86 machines (typically those 
with VIA chipsets).  Since that time, a test was devised that catches 
these issues.  This is why the aic79xx driver does not have an option 
to enable/disable memory mapped I/O.  It will use memory mapped I/O 
if possible on your system.  Similar tests can be introduced in other 
drivers so this type of option should not be necessary there either. 

I would be interested in understanding your performance problems with 
the ahd driver.  Please submit a different PR for that issue should 
it continue to occur. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=73642 
>Unformatted:
