netdev - Re: [PATCH] Implementation of the sendgroup() system call

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 04 May 2009 09:13:10 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Elad Lahav <elahav@...terloo.ca>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] Implementation of the sendgroup() system call

Elad Lahav <elahav@...terloo.ca> writes:

> The attached patch contains an implementation of sendgroup(), a system
> call that allows a UDP packet to be transmitted efficiently to
> multiple recipients. Use cases for this system call include
> live-streaming and multi-player online games.
> The basic idea is that the caller maintains a group - a list of IP
> addresses and UDP ports - and calls sendgroup() with the group list
> and a common payload. Optionally, the call allows for per-recipient
> data to be prepended or appended to the shared block. The data is
> copied once in the kernel into an allocated page, and the
> per-recipient socket buffers point to that page. Savings come from
> avoiding both the multiple calls and the multiple copies of the data
> required with regular socket operations.

My guess it's more the copies than the calls? It sounds like
you want sendfile() for UDP. I think that would be a cleaner solution
than such a specific hack for your application. It would
have the advantage of saving the first copy too and be 
truly zero copy on capable NICs.

Or perhaps simple send to a local multicast group and let
some netfilter module turn that into regular UDP.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html