netdev - Re: [PATCH iproute2] lib/libnetlink: ensure a minimum of 32KB for the buffer used in rtnl

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Message-ID: <20190214135130.GK25518@unicorn.suse.cz>
Date:   Thu, 14 Feb 2019 14:51:30 +0100
From:   Michal Kubecek <mkubecek@...e.cz>
To:     netdev@...r.kernel.org
Cc:     Hangbin Liu <liuhangbin@...il.com>,
        David Ahern <dsahern@...il.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Phil Sutter <phil@....cc>
Subject: Re: [PATCH iproute2] lib/libnetlink: ensure a minimum of 32KB for
 the buffer used in rtnl_recvmsg()

On Wed, Feb 13, 2019 at 02:20:12PM +0800, Hangbin Liu wrote:
>  
> > > Do we know of any single message sizes > 32k? 2d34851cd341 cites
> > > increasing VF's but at some point there is a limit. If not, the whole
> > > PEEK thing should go away and we just malloc 32k (or 64k) buffers for
> > > each recvmsg.
> 
> Apart from the 200 VFs example, I think there will be more and more virtual
> interfaces be used in cloud environment, like openstack/OVS, so useing 32K
> or 64K is still not safe.

Many intefraces are not a problem. Those will have separate messages so
that they don't need to fit into one buffer.

Michal Kubecek