From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: Anuj Kalia <anujkaliaiitd-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: Size of Infiniband packets
Date: Thu, 5 Dec 2013 16:53:34 -0700 [thread overview]
Message-ID: <20131205235334.GC20137@obsidianresearch.com> (raw)
In-Reply-To: <CADPSxAgSdWTkNBF=XEptKU0oVmqiXRVtd-m-c+ntnQyxMzDFNA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Thu, Dec 05, 2013 at 06:22:57PM -0500, Anuj Kalia wrote:
> I'm trying to do a back-of-the-hand calculation of the number of
> packets per second that can be transmitted over 40Gbps Infiniband. I
> need some information about the packet size to do this calculation.
>
> Suppose I do an 8 byte RDMA write over RC transport. What is the
> packet size that is transmitted on the wire? This should include
> Infiniband headers and the work request.
See page 257 (Figure 76) of IB Spec volume 1.
A RDMA write will contain:
LRH 8
BTH 12
RETH 16
data 8
ICRC 4
VCRC 2
Plus 2 bytes of framing is 52 bytes. IB is defined to sustain
continuous back-to-back packets, so
3200MB/sec / 52 bytes/packet = 615 million pkts/sec
--
Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> (780)4406067x832
Chief Technology Officer, Obsidian Research Corp Edmonton, Canada
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2013-12-05 23:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-05 23:22 Size of Infiniband packets Anuj Kalia
[not found] ` <CADPSxAgSdWTkNBF=XEptKU0oVmqiXRVtd-m-c+ntnQyxMzDFNA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-12-05 23:53 ` Jason Gunthorpe [this message]
[not found] ` <20131205235334.GC20137-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-12-06 15:31 ` Suresh Shelvapille
[not found] ` <1AC3E3259C454E07A5DD2216E79F2EA8-+IkoAhRkys/CbFgIbBqbbjGjJy/sRE9J@public.gmane.org>
2013-12-06 23:08 ` Anuj Kalia
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20131205235334.GC20137@obsidianresearch.com \
--to=jgunthorpe-epgobjl8dl3ta4ec/59zmfatqe2ktcn/@public.gmane.org \
--cc=anujkaliaiitd-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org \
--cc=linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.