From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [PATCH net-next 1/2] net: SOCKWQ_ASYNC_NOSPACE optimizations Date: Mon, 2 May 2016 21:12:29 +0200 Message-ID: <20160502191229.GA1946@nanopsycho.orion> References: <1461605974-4242-1-git-send-email-edumazet@google.com> <1461605974-4242-2-git-send-email-edumazet@google.com> <20160502161602.GA1984@nanopsycho.orion> <1462206138.5535.255.camel@edumazet-glaptop3.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Dumazet , "David S . Miller" , netdev , eladr@mellanox.com, idosch@mellanox.com To: Eric Dumazet Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:32840 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754722AbcEBTMc (ORCPT ); Mon, 2 May 2016 15:12:32 -0400 Received: by mail-wm0-f66.google.com with SMTP id r12so169685wme.0 for ; Mon, 02 May 2016 12:12:32 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1462206138.5535.255.camel@edumazet-glaptop3.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: Mon, May 02, 2016 at 06:22:18PM CEST, eric.dumazet@gmail.com wrote: >On Mon, 2016-05-02 at 18:16 +0200, Jiri Pirko wrote: >> Mon, Apr 25, 2016 at 07:39:32PM CEST, edumazet@google.com wrote: >> >SOCKWQ_ASYNC_NOSPACE is tested in sock_wake_async() >> >so that a SIGIO signal is sent when needed. >> > >> >tcp_sendmsg() clears the bit. >> >tcp_poll() sets the bit when stream is not writeable. >> > >> >We can avoid two atomic operations by first checking if socket >> >is actually interested in the FASYNC business (most sockets in >> >real applications do not use AIO, but select()/poll()/epoll()) >> > >> >This also removes one cache line miss to access sk->sk_wq->flags >> >in tcp_sendmsg() >> > >> >Signed-off-by: Eric Dumazet >> >> I just bisected down to this. This is causing a regression for me when >> my nfs mount becomes stuck. I can easily reproduce this if you need to >> test the fix. > >What do you mean by 'when nfs mount becomes stuck' ? > >Is this patch making nfs not functional , or does it make recovery from >some nfs error bad ? I can mount nfs on the host. But when I do something (compile a kernel module in my case), it gets stuck. Then I cannot even ssh to the machine. No messages in dmesg. I didn't debug it any further. I just bisected and verified that this patch caused this behaviour.