From nobody Mon Sep 13 06:21:15 2021 X-Original-To: virtualization@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id D674517A3551 for ; Mon, 13 Sep 2021 06:21:15 +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 "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4H7GZg5XVKz3MpV for ; Mon, 13 Sep 2021 06:21:15 +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 9DC842231D for ; Mon, 13 Sep 2021 06:21:15 +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 18D6LFMZ096528 for ; Mon, 13 Sep 2021 06:21:15 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 18D6LFwv096517 for virtualization@FreeBSD.org; Mon, 13 Sep 2021 06:21:15 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: virtualization@FreeBSD.org Subject: [Bug 254513] virtio_random: random_harvestq spinning on a CPU with Q35 virtio random device Date: Mon, 13 Sep 2021 06:21:15 +0000 X-Bugzilla-Reason: CC AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: misc X-Bugzilla-Version: 13.0-STABLE X-Bugzilla-Keywords: performance, regression X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: kevans@freebsd.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: virtualization@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc 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 List-Id: Discussion List-Archive: https://lists.freebsd.org/archives/freebsd-virtualization List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-virtualization@freebsd.org X-BeenThere: freebsd-virtualization@freebsd.org MIME-Version: 1.0 X-ThisMailContainsUnwantedMimeParts: N https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D254513 Kyle Evans changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bryanv@FreeBSD.org, | |cem@freebsd.org, | |jmg@FreeBSD.org, | |jrtc27@freebsd.org, | |kevans@freebsd.org, | |markm@FreeBSD.org --- Comment #17 from Kyle Evans --- (In reply to Chris Collins from comment #16) Can you provide details on the host here? I'm a little curious if qemu is configure to use a non-default backend for entropy, and what kernel version it's running. According to https://wiki.qemu.org/Features/VirtIORNG, the default is /dev/random which may block until more recent linux releases. I'm wondering= if we're depleting the host's /dev/random with our (10hz?) polling, frequently leaving us stuck in a tight spin here: https://cgit.freebsd.org/src/tree/sys/dev/virtio/virtqueue.c?h=3Dreleng/13.= 0#n605 -- CC'ing some csprng@ folks and some virtio folks. I wonder if it would make sense to add an optional timeout parameter to virtqueue_poll() so that rng doesn't get stuck if vtrnd can't currently contribute to the pool. --=20 You are receiving this mail because: You are on the CC list for the bug. You are the assignee for the bug.=