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

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Message-ID: <20190213135718.1ed23c3a@shemminger-XPS-13-9360>
Date:   Wed, 13 Feb 2019 13:57:18 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     David Ahern <dsahern@...il.com>, netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Hangbin Liu <liuhangbin@...il.com>, Phil Sutter <phil@....cc>
Subject: Re: [PATCH iproute2] lib/libnetlink: ensure a minimum of 32KB for
 the buffer used in rtnl_recvmsg()

On Tue, 12 Feb 2019 17:58:41 -0800
Eric Dumazet <edumazet@...gle.com> wrote:

> In the past, we tried to increase the buffer size up to 32 KB in order
> to reduce number of syscalls per dump.
> 
> Commit 2d34851cd341 ("lib/libnetlink: re malloc buff if size is not enough")
> brought the size back to 4KB because the kernel can not know the application
> is ready to receive bigger requests.
> 
> See kernel commits 9063e21fb026 ("netlink: autosize skb lengthes") and
> d35c99ff77ec ("netlink: do not enter direct reclaim from netlink_dump()")
> for more details.
> 
> Fixes: 2d34851cd341 ("lib/libnetlink: re malloc buff if size is not enough")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Hangbin Liu <liuhangbin@...il.com>
> Cc: Phil Sutter <phil@....cc>

Applied, although maybe we should bump it to 64K or bigger?