From owner-freebsd-net@freebsd.org Tue Mar 30 20:06:08 2021 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 E8CDD5AC0B7 for ; Tue, 30 Mar 2021 20:06:08 +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 4F90nX65Z7z3Gs8 for ; Tue, 30 Mar 2021 20:06:08 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id CF2C65ABC6F; Tue, 30 Mar 2021 20:06:08 +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 CEF0E5ABC6E for ; Tue, 30 Mar 2021 20:06:08 +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 4F90nX5Njjz3HCd for ; Tue, 30 Mar 2021 20:06:08 +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 A805A48B9 for ; Tue, 30 Mar 2021 20:06:08 +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 12UK68tb011652 for ; Tue, 30 Mar 2021 20:06:08 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 12UK68xD011651 for net@FreeBSD.org; Tue, 30 Mar 2021 20:06:08 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 254333] [tcp] sysctl net.inet.tcp.hostcache.list hangs Date: Tue, 30 Mar 2021 20:06:08 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.4-STABLE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: rscheff@freebsd.org X-Bugzilla-Status: In Progress X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: rscheff@freebsd.org X-Bugzilla-Flags: mfc-stable13? 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: 2.1.34 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 30 Mar 2021 20:06:09 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D254333 --- Comment #17 from Richard Scheffenegger --- net.inet.tcp.hostcache.count: 4294966447 is -849 (decimal). tcp_hc_purge_internal decrements hostcache.count unconditionally, and would= be=20 the most likely candidate where that counter can rapidely go negative (beco= ming a huge uint32). All the adjustments to hch_length, cache_count and actual add/dels from hashbuckets appear to be symmetric. One more hint (more operationally): if you have high "hostcache buffer-overflows" in 'netstat -snp tcp' you my want to tweak the bucket size rather than the hashsize. Unfortunately, the hostcache does not currently provide insight if a wider hashsize, or a deeper bucketlimit would be preferrential for your workload.= .. (you would probably want a histogram of #buckets of length "n". If that histogram shows few deeply used buckets, but most buckets empty or sparsely used, a narrower hashsize with deeper buckets may be more optimal space use. If most buckets are mostly used, a wider hashsize may be preferrably over deeper buckets... --=20 You are receiving this mail because: You are on the CC list for the bug.=