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Re: Queue and SMP locking discussion (was Re: 3c59x.c)

To: Andrew Morton <andrewm@xxxxxxxxxx>
Subject: Re: Queue and SMP locking discussion (was Re: 3c59x.c)
From: jamal <hadi@xxxxxxxxxx>
Date: Fri, 31 Mar 2000 08:55:53 -0500 (EST)
Cc: Donald Becker <becker@xxxxxxxxx>, netdev@xxxxxxxxxxx, kuznet@xxxxxxxxxxxxx
In-reply-to: <38E40D26.D34D72CB@xxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx

On Fri, 31 Mar 2000, Andrew Morton wrote:

> I believe that this tx starvation is due to the decision to schedule the
> tx in the device ISR, for BH handling, rather than to actually dequeue
> and send packets within the Tx ISR.  I can see why the bh scheduling is
> simpler...
> 
> I like the loop-until-max_interrupt_work-exceeded architecture.  It's
> _very_ efficient compared with interrupt per packet, and it kicks in
> when the system is under stress.  But it's not being leveraged for
> transmits.
> 

loop-until-max_interrupt_work-exceeded will *not* help you in this.
Packet arrivals still mean interupts.
Mitigation (which seems to be added to some of Donalds drivers by Jeff
Garzik and Andrey Savochkin) will to a certain extent.

cheers,
jamal


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