[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-bridge
Subject:    Re: [Bridge] Real time issues when using a bridge
From:       Jean-Michel Hautbois <jhautbois () gmail ! com>
Date:       2010-10-13 6:44:12
Message-ID: AANLkTinekwamO6frk0YM85ptVa79pNhO7Lk+n84b2_Db () mail ! gmail ! com
[Download RAW message or body]

[Attachment #2 (multipart/alternative)]


2010/10/13 Jean-Michel Hautbois <jhautbois@gmail.com>

> 2010/10/12 Stephen Hemminger <shemminger@linux-foundation.org>
>
>> > Thus, my jitter is 47=C2=B5s.
>> > This may seem low, but this is about two to three times what I expect
>> and I
>> > cannot see why a bridge which is only forwarding a frame would have
>> jitter ?
>> > If you have any idea, everything is interesting for me.
>> > I thought maybe to skb_clone ?
>>
>> You probably have NAPI and/or interrupt coalescing setting
>> enabled on one or both of the devices.
>>
>> --
>>
>
> Hi Stephen,
>
> I have NAPI on my ethernet device, at least.
> I will check for interrupt coalescing.
> AFAIK, there is a skb_clone followed by a kfree in netif_receive_skb (the
> frame coming from eth0 to br0).
> There is a jitter in this call of "freeing memory". I am looking at the
> path, in order to see why there is a clone.
>
> BR,
> JM
>

I have to tell I am working on a mpc52xx and am currently only interested i=
n
the eth->br path for the moment.
JM

[Attachment #5 (text/html)]

<div class="gmail_quote">2010/10/13 Jean-Michel Hautbois <span dir="ltr">&lt;<a \
href="mailto:jhautbois@gmail.com">jhautbois@gmail.com</a>&gt;</span><br><blockquote \
class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt \
0pt 0.8ex; padding-left: 1ex;"> <div class="gmail_quote">2010/10/12 Stephen Hemminger \
<span dir="ltr">&lt;<a href="mailto:shemminger@linux-foundation.org" \
target="_blank">shemminger@linux-foundation.org</a>&gt;</span><br><blockquote \
class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt \
0pt 0.8ex; padding-left: 1ex;"> <div class="im">
<div><div></div><div>&gt; Thus, my jitter is 47 µs.<br>
&gt; This may seem low, but this is about two to three times what I expect and I<br>
&gt; cannot see why a bridge which is only forwarding a frame would have jitter ?<br>
&gt; If you have any idea, everything is interesting for me.<br>
&gt; I thought maybe to skb_clone ?<br>

<br>
</div></div></div><div class="im">You probably have NAPI and/or interrupt coalescing \
setting<br> enabled on one or both of the devices.<br>
<font color="#888888"><br>
--<br>
</font></div></blockquote></div><br>Hi Stephen,<br><br>I have NAPI on my ethernet \
device, at least.<br>I will check for interrupt coalescing.<br>AFAIK, there is a \
skb_clone followed by a kfree in netif_receive_skb (the frame coming from eth0 to \
br0).<br>

There is a jitter in this call of &quot;freeing memory&quot;. I am looking at the \
path, in order to see why there is a clone.<br><br>BR,<br><font \
color="#888888">JM<br> </font></blockquote></div><br>I have to tell I am working on a \
mpc52xx and am currently only interested in the eth-&gt;br path for the \
moment.<br>JM<br>



_______________________________________________
Bridge mailing list
Bridge@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/bridge

[prev in list] [next in list] [prev in thread] [next in thread]