From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LzvLD-0006Bz-35 for qemu-devel@nongnu.org; Fri, 01 May 2009 12:11:59 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LzvL8-00064F-Av for qemu-devel@nongnu.org; Fri, 01 May 2009 12:11:58 -0400 Received: from [199.232.76.173] (port=43584 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LzvL8-00063x-4b for qemu-devel@nongnu.org; Fri, 01 May 2009 12:11:54 -0400 Received: from rv-out-0708.google.com ([209.85.198.242]:15692) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LzvL7-0008HI-Pd for qemu-devel@nongnu.org; Fri, 01 May 2009 12:11:53 -0400 Received: by rv-out-0708.google.com with SMTP id c5so1580236rvf.22 for ; Fri, 01 May 2009 09:11:52 -0700 (PDT) Message-ID: <49FB1F44.3080004@gmail.com> Date: Fri, 01 May 2009 10:11:48 -0600 From: David Ahern MIME-Version: 1.0 Subject: Re: [Qemu-devel] PATCH: enabling TCP keepalives - v3 References: <49F9FEBA.6050901@gmail.com> <200905011616.13164.paul@codesourcery.com> <49FB1BE4.30207@us.ibm.com> <200905011704.48102.paul@codesourcery.com> In-Reply-To: <200905011704.48102.paul@codesourcery.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Brook Cc: Anthony Liguori , qemu-devel@nongnu.org Paul Brook wrote: >> I don't think an option is very useful. If you lose your connection and >> now have a bunch of orphan connections, it's too late to have the >> foresight to have used an option on startup. In that case, it would be >> much better to just be able to close existing connections. >> >> I think there's a very, very small number of people that would have the >> foresight to always use keepalive=60 or whatever the option would be. > > In that case we should do nothing. Users with a flakey net connection can > tweak their kernel (via /proc/sys) to use lower timeouts. AFAICS There's no > way qemu can know what a "better" value is. As a concrete example my ADSL > connection takes between 90 and 180 seconds to resync after a noise spike, so > 60 seconds is absolutely the wrong timeout value here. > > Paul ie., just enable keepalives and use OS defaults? The linux default is 7200 seconds to start sending probes (which is 2 hours as Avi noted, not 7 hours as I misstated). I'll send an updated patch. david