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Date: Mon, 4 Mar 2002 10:46:09 -0700
From: "Jeff V. Merkey" <jmerkey@vger.timpanogas.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Gigabit Performance 2.4.19-preX - Excessive locks, calls, waits
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In-Reply-To: <E16hu0P-0007yq-00@the-village.bc.nu>; from alan@lxorguk.ukuu.org.uk on Mon, Mar 04, 2002 at 03:04:00PM +0000
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On Mon, Mar 04, 2002 at 03:04:00PM +0000, Alan Cox wrote:
> > provided for review.  Recommend a minumum change of increasing 
> > the sysctl_hot_list_len from 128 to 1024 by default.  I have reviewed 
> 
> Good way to kill low end boxes. It probably wants sizing based on system
> size and load monitoring. 
> 
> > NetWare always created ECB's (Event Control Blocks) at the max size
> > of the network adpapter rather than trying to allocate fragment 
> > elements on the fly the way is being done in Linux with skb's.  
> 
> Thats up to the network adapter. In fact the Linux drivers mostly do 
> keep preloaded with full sized buffers and only copy if the packet size
> is small (and copying 1 or 2 cache lines isnt going to hurt anyone)


There's an increase in latency.  For my application, I have no 
problem keeping around a local patch that corrects this behavior 
if folks don't feel it needs fixing.   From everything I've ever
done in this space, having needless alloc/free calls in a 
performance intensive path that requires low latency like a Lan 
driver is not a good thing.  

I am idle most of the time since I have eliminated all of the 
copy activity by using SCI in the system.  This is why it's 
idle most of the time.  Were I using the IP stack code in Linux
proper, the utilization would be through the roof.  

:-)

Jeff


> 
> >  28044 default_idle                             584.2500
> 
> You spent most of your time asleep 8)
> 
> >   1117 __rdtsc_delay                             34.9062
> 
> Or doing delays
> 
> >    927 eth_type_trans                             4.4567
> 
> And pulling a line into L1 cache
-
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