From owner-dev-commits-src-branches@freebsd.org Fri Apr 16 21:32:24 2021 Return-Path: Delivered-To: dev-commits-src-branches@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 C5A015E14E1; Fri, 16 Apr 2021 21:32:24 +0000 (UTC) (envelope-from git@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 4FMTvD5Hdwz4sTV; Fri, 16 Apr 2021 21:32:24 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (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 9DF5A3AF1; Fri, 16 Apr 2021 21:32:24 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 13GLWOpm033915; Fri, 16 Apr 2021 21:32:24 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 13GLWOjg033914; Fri, 16 Apr 2021 21:32:24 GMT (envelope-from git) Date: Fri, 16 Apr 2021 21:32:24 GMT Message-Id: <202104162132.13GLWOjg033914@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Richard Scheffenegger Subject: git: 54beb1ef2c83 - stable/12 - tcp: reduce memory footprint when listing tcp hostcache MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: rscheff X-Git-Repository: src X-Git-Refname: refs/heads/stable/12 X-Git-Reftype: branch X-Git-Commit: 54beb1ef2c831394ef908ef52bac690a4fe362e0 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-branches@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commits to the stable branches of the FreeBSD src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Apr 2021 21:32:24 -0000 The branch stable/12 has been updated by rscheff: URL: https://cgit.FreeBSD.org/src/commit/?id=54beb1ef2c831394ef908ef52bac690a4fe362e0 commit 54beb1ef2c831394ef908ef52bac690a4fe362e0 Author: Richard Scheffenegger AuthorDate: 2021-03-28 21:12:03 +0000 Commit: Richard Scheffenegger CommitDate: 2021-04-16 20:51:57 +0000 tcp: reduce memory footprint when listing tcp hostcache In tcp_hostcache_list, the sbuf used would need a large (~2MB) blocking allocation of memory (M_WAITOK), when listing a full hostcache. This may stall the requestor for an indeterminate time. A further optimization is to return the expected userspace buffersize right away, rather than preparing the output of each current entry of the hostcase, provided by: @tuexen. This makes use of the ready-made functions of sbuf to work with sysctl, and repeatedly drain the much smaller buffer. PR: 254333 MFC after: 2 weeks Reviewed By: #transport, tuexen Sponsored by: NetApp, Inc. Differential Revision: https://reviews.freebsd.org/D29471 (cherry picked from commit cb0dd7e122b8936ad61a141e65ef8ef874bfebe5) --- sys/netinet/tcp_hostcache.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/sys/netinet/tcp_hostcache.c b/sys/netinet/tcp_hostcache.c index 2753d511c9d5..6dfe3941c9d8 100644 --- a/sys/netinet/tcp_hostcache.c +++ b/sys/netinet/tcp_hostcache.c @@ -625,7 +625,7 @@ sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS) { const int linesize = 128; struct sbuf sb; - int i, error; + int i, error, len; struct hc_metrics *hc_entry; char ip4buf[INET_ADDRSTRLEN]; #ifdef INET6 @@ -635,11 +635,22 @@ sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS) if (jailed_without_vnet(curthread->td_ucred) != 0) return (EPERM); - sbuf_new(&sb, NULL, linesize * (V_tcp_hostcache.cache_count + 1), - SBUF_INCLUDENUL); + /* Optimize Buffer length query by sbin/sysctl */ + if (req->oldptr == NULL) { + len = (V_tcp_hostcache.cache_count + 1) * linesize; + return (SYSCTL_OUT(req, NULL, len)); + } + + error = sysctl_wire_old_buffer(req, 0); + if (error != 0) { + return(error); + } + + /* Use a buffer for 16 lines */ + sbuf_new_for_sysctl(&sb, NULL, 16 * linesize, req); sbuf_printf(&sb, - "\nIP address MTU SSTRESH RTT RTTVAR " + "\nIP address MTU SSTRESH RTT RTTVAR " " CWND SENDPIPE RECVPIPE HITS UPD EXP\n"); #define msec(u) (((u) + 500) / 1000) @@ -674,8 +685,6 @@ sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS) } #undef msec error = sbuf_finish(&sb); - if (error == 0) - error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb)); sbuf_delete(&sb); return(error); }