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Date: Wed, 18 Feb 2004 09:12:34 -0800 (PST)
From: Marian Durkovic <md@bts.sk>
To: freebsd-gnats-submit@FreeBSD.org
Subject: bad TX performance of xl driver for 3COM 905C cards
X-Send-Pr-Version: www-2.3

>Number:         63027
>Category:       i386
>Synopsis:       bad TX performance of xl driver for 3COM 905C cards
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-i386
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Feb 18 09:20:10 PST 2004
>Closed-Date:    Mon Jul 05 21:13:16 GMT 2004
>Last-Modified:  Mon Jul 05 21:13:16 GMT 2004
>Originator:     Marian Durkovic
>Release:        4.9
>Organization:
Slovak Technical University
>Environment:
>Description:
The xl driver is not able to achieve wire-speed performance for TX direction. The nttcp test shows significant performance degradadion for TX direction as compared to RX direction which is able to run at theoretical limit without problems. Looks like the heavy use of TX path actually blocks the RX direction, and therefore TCP ACKs are being delivered with significant delay (like 24 msec) - verified by tcpdump. Here are the example values from nttcp:

box with Intel E100 PRO -> box with 3c905

     Bytes  Real s   CPU s Real-MBit/s  CPU-MBit/s   Calls  Real-C/s   CPU-C/s
l409600000   34.80    2.96     94.1489   1105.1982  100000   2873.20   33728.0
1409600000   34.82    1.18     94.1175   2773.2828  281323   8080.27  238094.6

box with 3c905 -> box with Intel E100 Pro

     Bytes  Real s   CPU s Real-MBit/s  CPU-MBit/s   Calls  Real-C/s   CPU-C/s
l409600000   38.86    1.18     84.3323   2766.3223  282788   7277.88  238733.7
1409600000   38.85    1.56     84.3524   2100.2557  100000   2574.23   64094.7




>How-To-Repeat:
Run nttcp     


>Fix:
      
>Release-Note:
>Audit-Trail:

From: Marian Durkovic <md@bts.sk>
To: FreeBSD-gnats-submit@FreeBSD.org
Cc:  
Subject: Re: i386/63027: bad TX performance of xl driver for 3COM 905C cards
Date: Thu, 19 Feb 2004 16:00:54 +0100

 The problem seems to disappear when hardware checksuming is disabled for TX
 direction. HW checksuming for receive direction can be kept enabled.
 
 	M.
State-Changed-From-To: open->closed 
State-Changed-By: bms 
State-Changed-When: Mon Jul 5 21:13:00 GMT 2004 
State-Changed-Why:  
Dealt with in rev 1.67 of if_xl.c and MFC'd. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=63027 
>Unformatted:
