From owner-freebsd-net@freebsd.org Sun Jan 26 20:52:52 2020 Return-Path: Delivered-To: freebsd-net@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 3DD111FB527 for ; Sun, 26 Jan 2020 20:52:52 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 485Q7S0xTbz4V1T for ; Sun, 26 Jan 2020 20:52:52 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id 2029E1FB526; Sun, 26 Jan 2020 20:52:52 +0000 (UTC) Delivered-To: net@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 1FF301FB525 for ; Sun, 26 Jan 2020 20:52:52 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 485Q7S04DBz4V1S for ; Sun, 26 Jan 2020 20:52:52 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id F201C26F0A for ; Sun, 26 Jan 2020 20:52:51 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 00QKqpkm095976 for ; Sun, 26 Jan 2020 20:52:51 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 00QKqpxP095975 for net@FreeBSD.org; Sun, 26 Jan 2020 20:52:51 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: net@FreeBSD.org Subject: [Bug 207261] netmap: Doesn't do TX sync with kqueue Date: Sun, 26 Jan 2020 20:52:51 +0000 X-Bugzilla-Reason: CC AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 10.2-STABLE X-Bugzilla-Keywords: needs-patch, needs-qa X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: vmaffione@FreeBSD.org X-Bugzilla-Status: Open X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: net@FreeBSD.org X-Bugzilla-Flags: maintainer-feedback? mfc-stable12? mfc-stable11? mfc-stable10? X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: 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-net@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 26 Jan 2020 20:52:52 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D207261 --- Comment #9 from Vincenzo Maffione --- Sorry for being unresponsive on this. The root of the problem is that when netmap was designed, kqueue was not ta= ken in consideration. Support for kqueue was added afterwards. Because of that, there are some locking issues that make it hard for netmap to work well with kqueue. The massive taskqueue usage that you observe are due to recent changes (r34= 3579 and r344253) that fixed a possible deadlock (e.g. with bhyve guests). It's unfortunate that netmap works so bad with kqueue. I would really like = to improve the situation, as soon as I have some time to spend on this. It wou= ld also really help to have some opinion from people that know the kqueue internals, as I currently have very little knowledge. --=20 You are receiving this mail because: You are on the CC list for the bug. You are the assignee for the bug.=