From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCHv1 net] xen-netback: support frontends without feature-rx-notify again Date: Thu, 18 Dec 2014 17:55:31 +0000 Message-ID: <54931513.8040606@citrix.com> References: <1418901186-14478-1-git-send-email-david.vrabel@citrix.com> <20141218.125009.1837191564956948256.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Cc: , , , To: David Miller Return-path: Received: from smtp.citrix.com ([66.165.176.89]:27001 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750954AbaLRR4T (ORCPT ); Thu, 18 Dec 2014 12:56:19 -0500 In-Reply-To: <20141218.125009.1837191564956948256.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 18/12/14 17:50, David Miller wrote: > From: David Vrabel > Date: Thu, 18 Dec 2014 11:13:06 +0000 > >> Commit bc96f648df1bbc2729abbb84513cf4f64273a1f1 (xen-netback: make >> feature-rx-notify mandatory) incorrectly assumed that there were no >> frontends in use that did not support this feature. But the frontend >> driver in MiniOS does not and since this is used by (qemu) stubdoms, >> these stopped working. >> >> Netback sort of works as-is in this mode except: >> >> - If there are no Rx requests and the internal Rx queue fills, only >> the drain timeout will wake the thread. The default drain timeout >> of 10 s would give unacceptable pauses. >> >> - If an Rx stall was detected and the internal Rx queue is drained, >> then the Rx thread would never wake. >> >> Handle these two cases (when feature-rx-notify is disabled) by: >> >> - Reducing the drain timeout to 30 ms. >> >> - Disabling Rx stall detection. >> >> Reported-by: John >> Tested-by: John >> Signed-off-by: David Vrabel > > Applied, and I assume that 3.18 -stable needs this as well? Yes, please. Without it, netback just doesn't work with an important use case. Thanks. David