From owner-freebsd-bugs@freebsd.org Fri Mar 30 04:21:58 2018 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E098AF6F214 for ; Fri, 30 Mar 2018 04:21:57 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 7ACD8755B1 for ; Fri, 30 Mar 2018 04:21:57 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id A547F3125 for ; Fri, 30 Mar 2018 04:21:56 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id w2U4LuZt045013 for ; Fri, 30 Mar 2018 04:21:56 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id w2U4LuRQ045003 for freebsd-bugs@FreeBSD.org; Fri, 30 Mar 2018 04:21:56 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 227100] [epair] epair interface stops working when it reaches the hardware queue limit Date: Fri, 30 Mar 2018 04:21:56 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: reshadpatuck1@gmail.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter attachments.created Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Mar 2018 04:21:58 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D227100 Bug ID: 227100 Summary: [epair] epair interface stops working when it reaches the hardware queue limit Product: Base System Version: CURRENT Hardware: amd64 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: reshadpatuck1@gmail.com Created attachment 191964 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D191964&action= =3Dedit the output of netstat and dtrace When the epair interface reaches the hardware queue limit, epairs stop transferring data. This bug refers to this mailing list conversation https://lists.freebsd.org/pipermail/freebsd-net/2018-March/050077.html So far using the patch/if_epair source file attached to this bug we can tell that the error occurs in this block of code ``` if ((epair_dpcpu->epair_drv_flags & IFF_DRV_OACTIVE) !=3D 0) { /* * Our hardware queue is full, try to fall back * queuing to the ifq but do not call ifp->if_start. * Either we are lucky or the packet is gone. */ IFQ_ENQUEUE(&ifp->if_snd, m, error); if (!error) (void)epair_add_ifp_for_draining(ifp); SDT_PROBE3(if_epair, transmit, epair_transmit_locked, enque= ued, ifp, m, error); return (error); } ``` Where the value of the 'error' is 55. Setting 'net.link.epair.netisr_maxqlen' to a very small value makes this oc= cur faster. This issue seems to be happening in the wild only on one of my servers. Other servers under more load in different environments do not seem to exhi= bit this behaviour. @Kristof please chime in if I have missed something out. Attached: - commands.txt - epair-sdt-diff.patch=20 - epair_transmit_locked:enqueued-error-code.d - if_epair.c --=20 You are receiving this mail because: You are the assignee for the bug.=