netdev - Re: [Patch net 01/16] net_sched: introduce a workqueue for RCU callbacks of tc filter

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

Message-ID: <CAM_iQpUxG3Bqkg2HJMjAKGe4Cg8TXCDsdSaHYoF_e7oNwWOmwg@mail.gmail.com>
Date:   Fri, 27 Oct 2017 08:43:34 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Chris Mi <chrism@...lanox.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jiri Pirko <jiri@...nulli.us>,
        John Fastabend <john.fastabend@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [Patch net 01/16] net_sched: introduce a workqueue for RCU
 callbacks of tc filter

On Fri, Oct 27, 2017 at 4:55 AM, Paul E. McKenney
<paulmck@...ux.vnet.ibm.com> wrote:
>
> Would this be a good time for me to repeat my suggestion that timers
> be used to aggregate the work done in the workqueue handlers, thus
> decreasing the number of rcu_barrier() calls done under RTNL?
>

Yes, but not in this patchset. The current code is already so, therefore
needs a different patchset.

Quite contrarily, my patchset actually improves it _a little bit_ by moving
the second rcu_barrier() in current code base to a workqueue... The
contention is same, just that we no longer block tcf_block_put() path
with my patchset.