Date:	Tue, 20 Nov 2012 16:05:36 +0100
From:	Javier Domingo <javierdo1@...il.com>
To:	netdev@...r.kernel.org
Subject: Fwd: Network soft and hard irqs statistics

I have released the mentioned code in

https://github.com/txomon/linux

It now is giving some kernel panics due to some page fault during
net_rx_action because I didn't know how to put this in current kernel,
but I am currently working in an alternative solution

https://github.com/txomon/linux/blob/affde7645451eb62cdd1993a8cef7b5325e30b96/net/core/dev.c#L3944

Hope someone can help me now :D

Javier Domingo



2012/11/15 Javier Domingo <javierdo1@...il.com>
>
> Hello all,
>
> I am migrating some statistics we use in our research group to v3.6.
> This I don't think it will be usefull for anyone, as they measure
> softirqs, hardirqs, times on them, etc.
>
> We modified net_device structure to contain a structure that has
> several field of statistics.
>
> Patched the e1000 and tg3 drivers to measure hardirq times, and
> polling times. We also patched net_rx_action (the softirq) to check if
> we get out per budget, per jiffies and netif_receive_skb to measure
> times and how many packets are captured.
>
> At the moment, we have been working with a external module that
> accessed this vars, creating proc entries, and allowing us to reset
> those measures.
>
> Now, I am trying to make it the most standard way, with the intention
> that when I talk to my boss, he will allow me to release the code.
>
> The main aim of this is to get some feedback about the interest this
> can have and to ask a few questions:
>
> -> Where may I create the proc entry? we currently use
> /proc/net/stats/<netdev>. I have also thought introducing that entry
> in fs/proc/proc_net.c, but I am not too sure which conventions there
> are...
>
> -> When migrating the net_rx_action, I found that we used this line:
> if(cpus_equal(mask,irq_desc[timedev->irq].affinity))
> before counting if we get out by budget or by jiffies to (I suppose)
> check that the softirq was the one assigned to this processor. Is that
> needed? I mean the softirq is run in just one of them... I don't
> really understand why it is important, so if anyone can explain me, I
> would be glad.
>
> -> We have patched the hardirqs in the driver, and the polling times
> too. I know the hardirqs are the only place in which we can measure
> them, but would it be posible to, instead of measuring the polls in
> e1000_clean (for example) measuring in dev.c net_rx_action, measure
> them around n->poll() call?
>    Have been doing like this because they told me that the context
> change was important... But I am not too sure on how important it is,
> if someone could give me any tip on this.
>
> -> In tg3.c I have seen that there are several hardirq function,
> though we usually only patched tg3_interrupt_tagged, I have patched
> all of them (for what they might be). Why are so many of them? Is that
> due to preparation for multiqueue cards?
>
> I hope someone can attend my doubts, and that I dont have asked too
> many newbie questions.
>
> Best regards,
>
> Javier Domingo
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