Hello all, I'm forwarding a patch for the loopback setup from Stéphane. I already pushed one part of it as http://cgit.freedesktop.org/systemd/systemd/commit/?id=58a489c which is trivial and obvious, but the other part isn't.
Thanks, Martin ----- Forwarded message from Stéphane Graber <stgra...@ubuntu.com> ----- Date: Thu, 25 Dec 2014 22:17:52 +0100 From: Stéphane Graber <stgra...@ubuntu.com> To: martin.p...@ubuntu.com Subject: systemd patch for unprivileged containers X-Spam-Status: No, score=-1.9 required=3.4 tests=BAYES_00 autolearn=no version=3.3.2 Hey Martin, Attached is a pretty simple patch/workaround to fix the massive CPU usage of systemd in unprivileged containers. LXC provides each containers with an already-UP loopback device. systemd will attempt to bring it up regardless of its current state and doing so gets it into a broken codepath somewhere deep in the netlink handling code of systemd. The fix is to always check whether the loopback is ready to use before doing anything. I then noticed that this code path in systemd was broken too due to it checking against 1.0.0.127 rather than 127.0.0.1 so I added the missing htonl and now it all works as expected and systemd fails on the next problem about a minute faster than it used to :) -- Stéphane Graber Ubuntu developer http://www.ubuntu.com ----- End forwarded message ----- -- Martin Pitt | http://www.piware.de Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org)
From af71697dcc084b81f4c585c4b0c9dd6ac51b77d7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Graber?= <stgra...@ubuntu.com>
Date: Sat, 27 Dec 2014 19:22:58 +0100
Subject: [PATCH] core: Optimize loopback setup
Check if the loopback device is already set up (like with LXC) before doing any
setup ourselves.
---
src/core/loopback-setup.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/src/core/loopback-setup.c b/src/core/loopback-setup.c
index ab6335c..e46b70a 100644
--- a/src/core/loopback-setup.c
+++ b/src/core/loopback-setup.c
@@ -86,15 +86,15 @@ int loopback_setup(void) {
_cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
int r;
+ if (check_loopback())
+ return 0;
+
r = sd_rtnl_open(&rtnl, 0);
if (r < 0)
return r;
r = start_loopback(rtnl);
- if (r == -EPERM) {
- if (check_loopback() < 0)
- return log_warning_errno(EPERM, "Failed to configure loopback device: %m");
- } else if (r < 0)
+ if (r < 0)
return log_warning_errno(r, "Failed to configure loopback device: %m");
--
2.1.3
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