netdev
[Top] [All Lists]

Re: Info: NAPI performance at "low" loads

To: jgarzik@xxxxxxxxxxxxxxxx
Subject: Re: Info: NAPI performance at "low" loads
From: "David S. Miller" <davem@xxxxxxxxxx>
Date: Tue, 17 Sep 2002 14:49:11 -0700 (PDT)
Cc: akpm@xxxxxxxxx, manfred@xxxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
In-reply-to: <3D87A4A2.6050403@xxxxxxxxxxxxxxxx>
References: <3D87A264.8D5F3AD2@xxxxxxxxx> <20020917.143947.07361352.davem@xxxxxxxxxx> <3D87A4A2.6050403@xxxxxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
   From: Jeff Garzik <jgarzik@xxxxxxxxxxxxxxxx>
   Date: Tue, 17 Sep 2002 17:54:42 -0400

   David S. Miller wrote:
   > Any driver should be able to get the NAPI overhead to max out at
   > 2 PIOs per packet.
   
   Just to pick nits... my example went from 2 or 3 IOs [depending on the 
   presence/absence of a work loop] to 6 IOs.
   
I mean "2 extra PIOs" not "2 total PIOs".

I think it's doable for just about every driver, even tg3 with it's
weird semaphore scheme takes 2 extra PIOs worst case with NAPI.

The semaphore I have to ACK anyways at hw IRQ time anyways, and since
I keep a software copy of the IRQ masking register, mask and unmask
are each one PIO.


<Prev in Thread] Current Thread [Next in Thread>