From owner-freebsd-net@freebsd.org Mon Aug 31 22:06:03 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 08E463CFD9A for ; Mon, 31 Aug 2020 22:06:03 +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 4BgPRG4mrjz4Clm for ; Mon, 31 Aug 2020 22:06:02 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id 6D0DA3CFC50; Mon, 31 Aug 2020 22:06:02 +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 64D0D3CFF45 for ; Mon, 31 Aug 2020 22:06:02 +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) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 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 4BgPRF5DGJz4Cnq for ; Mon, 31 Aug 2020 22:06:01 +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) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id A90F7EB2D for ; Mon, 31 Aug 2020 22:06:00 +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 07VM60Et045567 for ; Mon, 31 Aug 2020 22:06:00 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 07VM60XW045566 for net@FreeBSD.org; Mon, 31 Aug 2020 22:06:00 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 248652] netmap: pkt-gen TX huge pps difference between 11-STABLE and 12-STABLE/CURRENT on ix & ixl NIC Date: Mon, 31 Aug 2020 22:05:59 +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: CURRENT X-Bugzilla-Keywords: iflib, needs-qa, performance, regression X-Bugzilla-Severity: Affects Only Me 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? maintainer-feedback? mfc-stable12? mfc-stable11- 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: 2.1.33 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 31 Aug 2020 22:06:03 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D248652 --- Comment #9 from Vincenzo Maffione --- Thanks a lot for the tests. I think the way netmap tx is handled right now needs improvement. As far as I can tell, in your setup TX interrupts are simply not used (ix a= nd ixl seem to use softirq for TX interrupt processing). Your experiments with increasing kern.hz cause the interrupt rate of the OS timer to increase, and therefore causing the iflib_timer() routine to be ca= lled more often. Being called more often, the TX ring is cleaned up (TX credits update) more often and therefore the application can submit new TX packets = more often, hence the improved pps. However, clearly increasing kern.hz is not a viable approach. I think we should try to use a separate timer for netmap TX credits update, using higher resolution (e.g. callout_reset_sbt_on()), and maybe try to dynamically adjust the timer period to become smaller when transmitting at = high rate, and lower when transmitting ad low rate. I'll try to come up with an experimental patch in the next days. --=20 You are receiving this mail because: You are on the CC list for the bug. You are the assignee for the bug.=