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Re: [RFC] netif_rx: receive path optimization

To: Stephen Hemminger <shemminger@xxxxxxxx>
Subject: Re: [RFC] netif_rx: receive path optimization
From: Jamal Hadi Salim <hadi@xxxxxxxx>
Date: 31 Mar 2005 16:10:32 -0500
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>, netdev <netdev@xxxxxxxxxxx>
In-reply-to: <20050331120410.7effa94d@dxpl.pdx.osdl.net>
Organization: Znyx Networks
References: <20050330132815.605c17d0@dxpl.pdx.osdl.net> <20050331120410.7effa94d@dxpl.pdx.osdl.net>
Reply-to: hadi@xxxxxxxx
Sender: netdev-bounce@xxxxxxxxxxx
On Thu, 2005-03-31 at 15:04, Stephen Hemminger wrote:
> Here is another alternative that seems better than the earlier posting. It 
> uses
> a per device receive queue for non-NAPI devices.  The only issue is that then
> we lose the per-cpu queue's and that could impact the loopback device 
> performance.
> If that is really an issue, then the per-cpu magic should be moved to the 
> loopback
> device.
> 

The repurcassions of going from per-CPU-for-all-devices queue
(introduced by softnet) to per-device-for-all-CPUs maybe huge in my
opinion especially in SMP. A closer view of whats there now maybe
per-device-per-CPU backlog queue.
I think performance will be impacted in all devices. imo, whatever needs
to go in needs to have some experimental data to back it

cheers,
jamal


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