From: Ben Pfaff <blp@nicira•com>
To: Thomas Graf <tgraf@redhat•com>
Cc: jesse@nicira•com, dev@openvswitch•org, netdev@vger•kernel.org,
dborkman@redhat•com, ffusco@redhat•com, fleitner@redhat•com,
xiyou.wangcong@gmail•com
Subject: Re: [PATCH openvswitch v3] netlink: Implement & enable memory mapped netlink i/o
Date: Wed, 4 Dec 2013 08:33:28 -0800 [thread overview]
Message-ID: <20131204163328.GE30874@nicira.com> (raw)
In-Reply-To: <1d9af26b2798901c68ae9aef704d6313b71d3287.1386069453.git.tgraf@redhat.com>
On Tue, Dec 03, 2013 at 12:19:02PM +0100, Thomas Graf wrote:
> Based on the initial patch by Cong Wang posted a couple of months
> ago.
>
> This is the user space counterpart needed for the kernel patch
> '[PATCH net-next 3/8] openvswitch: Enable memory mapped Netlink i/o'
>
> Allows the kernel to construct Netlink messages on memory mapped
> buffers and thus avoids copying. The functionality is enabled on
> sockets used for unicast traffic.
>
> Further optimizations are possible by avoiding the copy into the
> ofpbuf after reading.
>
> Signed-off-by: Thomas Graf <tgraf@redhat•com>
If I'm doing the calculations correctly, this mmaps 8 MB per ring-based
Netlink socket on a system with 4 kB pages. OVS currently creates one
Netlink socket for each datapath port. With 1000 ports (a moderate
number; we sometimes test with more), that is 8 GB of address space. On
a 32-bit architecture that is impossible. On a 64-bit architecture it
is possible but it may reserve an actual 8 GB of RAM: OVS often runs
with mlockall() since it is something of a soft real-time system (users
don't want their packet delivery delayed to page data back in).
Do you have any thoughts about this issue?
next prev parent reply other threads:[~2013-12-04 16:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-03 11:19 [PATCH openvswitch v3] netlink: Implement & enable memory mapped netlink i/o Thomas Graf
[not found] ` <1d9af26b2798901c68ae9aef704d6313b71d3287.1386069453.git.tgraf-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-12-04 1:54 ` 答复: " Zhuangyuxin
[not found] ` <9C2DE4B8FE85984BA1B0581235F6B2ED0F5D440A-tJwL4pWccCZdGU6diIvhbAK1hpo4iccwjNknBlVQO8k@public.gmane.org>
2013-12-04 9:08 ` Thomas Graf
2013-12-04 16:33 ` Ben Pfaff [this message]
2013-12-04 17:20 ` Thomas Graf
[not found] ` <529F6475.3090903-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-12-04 17:56 ` Kais Belgaied
2013-12-04 18:08 ` Ben Pfaff
2013-12-04 21:48 ` Thomas Graf
2013-12-04 22:20 ` Jesse Gross
2013-12-05 22:08 ` Thomas Graf
2013-12-05 22:54 ` Ben Pfaff
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