From owner-dev-commits-src-branches@freebsd.org Fri Apr 16 22:11:58 2021
Return-Path: <owner-dev-commits-src-branches@freebsd.org>
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 E93D35E2EE7;
Fri, 16 Apr 2021 22:11:58 +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 4FMVmt5r1Bz3Bs1;
Fri, 16 Apr 2021 22:11:58 +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 BB45F4C19;
Fri, 16 Apr 2021 22:11:58 +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 13GMBwVW087152;
Fri, 16 Apr 2021 22:11:58 GMT (envelope-from git@gitrepo.freebsd.org)
Received: (from git@localhost)
by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 13GMBwvU087151;
Fri, 16 Apr 2021 22:11:58 GMT (envelope-from git)
Date: Fri, 16 Apr 2021 22:11:58 GMT
Message-Id: <202104162211.13GMBwvU087151@gitrepo.freebsd.org>
To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org,
dev-commits-src-branches@FreeBSD.org
From: Richard Scheffenegger <rscheff@FreeBSD.org>
Subject: git: c449b8a71bce - stable/11 - 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/11
X-Git-Reftype: branch
X-Git-Commit: c449b8a71bce7d7838164f6a5595f71c91b5b91b
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
<dev-commits-src-branches.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/dev-commits-src-branches>,
<mailto:dev-commits-src-branches-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/dev-commits-src-branches/>
List-Post: <mailto:dev-commits-src-branches@freebsd.org>
List-Help: <mailto:dev-commits-src-branches-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/dev-commits-src-branches>,
<mailto:dev-commits-src-branches-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 16 Apr 2021 22:11:59 -0000
The branch stable/11 has been updated by rscheff:
URL: https://cgit.FreeBSD.org/src/commit/?id=c449b8a71bce7d7838164f6a5595f71c91b5b91b
commit c449b8a71bce7d7838164f6a5595f71c91b5b91b
Author: Richard Scheffenegger <rscheff@FreeBSD.org>
AuthorDate: 2021-03-28 21:12:03 +0000
Commit: Richard Scheffenegger <rscheff@FreeBSD.org>
CommitDate: 2021-04-16 21:33:09 +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 9b5680020a1d..e71f13243f0c 100644
--- a/sys/netinet/tcp_hostcache.c
+++ b/sys/netinet/tcp_hostcache.c
@@ -621,7 +621,7 @@ 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
@@ -631,11 +631,22 @@ 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)
@@ -670,8 +681,6 @@ 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);
}