[TriLUG] scheduling of reception of packets by a "protocol stack"
reginald.reed at gmail.com
Sat Jun 14 19:50:42 EDT 2008
It could - it depends on a lot more information. Particularly the
configuration of the system, how complex the network protocol is, how
many cpus/cores, whether the protocol code is multithreaded, etc, etc.
I couldn't find a really good reference, but this article does talk
about zero copy stuff in relation to context switching and
specifically how it can be reduced.
On Sat, Jun 14, 2008 at 12:45 PM, James Olin Oden <james.oden at gmail.com> wrote:
> So does this answer the context switch issue they are trying to
> avoid...essentially they are dong in kernel filtering for better
> performance? Course I wonder if the packet filter interface in the
> kernel might be the better way to implement this.
> On Sat, Jun 14, 2008 at 11:47 AM, Reginald Reed <reginald.reed at gmail.com> wrote:
>> Howdy James!
>> Have they considered using zero copy drivers + user protocol stacks?
>> This maps a section of ram that the Ethernet port dma's directly
>> into. You then have full control to do whatever you want in userspace.
>> Sent from my iPhone
>> On Jun 14, 2008, at 11:13 AM, "James Olin Oden" <james.oden at gmail.com>
>>> Hi All,
>>> So here is the really simple high level problem I'm seeing. A group
>>> of developers have developed a protocol that sits on top of an
>>> ethernet driver (e1000). When the ethernet driver hands off the
>>> packet it received to the protocol it seems to be always running the
>>> protocols callback on the same processor its bottom end received the
>>> packet upon. In this case due to some heavy in kernel processing (I
>>> know bad idea, but sometimes you end up here) this ends up saturating
>>> the processing capability of this lone processor.
>>> So here are my questions:
>>> 1) How does the kernel schedule the hand off of a packet to a
>>> protocol from its layer 2 drivers?
>>> 2) Where is the code that handles this scheduling in the kernel
>>> 3) Where else might I ask this question? I'm trying to avoid the
>>> linux kernel list for various reasons, but if there is a smaller
>>> list where newbies to linux kernel networking might ask
>>> questions I'd be pleased to know that.
>>> TriLUG mailing list : http://www.trilug.org/mailman/listinfo/trilug
>>> TriLUG FAQ : http://www.trilug.org/wiki/Frequently_Asked_Questions
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