Date: Wed, 14 Dec 2011 14:51:43 -0800 From: Doug Barton <dougb@FreeBSD.org> To: Dan Nelson <dnelson@allantgroup.com> Cc: freebsd-stable@freebsd.org Subject: Re: kernel: negative sbsize for uid = 0 Message-ID: <4EE9287F.9060704@FreeBSD.org> In-Reply-To: <20111214194630.GI53453@dan.emsphone.com> References: <4EE29D3F.2030009@gridfury.com> <4EE7C920.3010109@FreeBSD.org> <20111214194630.GI53453@dan.emsphone.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 12/14/2011 11:46, Dan Nelson wrote: > In the last episode (Dec 13), Doug Barton said: >> I'm running 8.2-RELEASE-p4 i386 on some web servers that are generally >> lightly-moderately loaded, but occasionally see some heavy spikes where >> load average goes way up. When that is happening, but sometimes even when >> it's not, I get hundreds of this message spewing into the logs: >> >> kernel: negative sbsize for uid = 0 >> >> I haven't found anything particularly useful by searching for that >> message, the one reference was to mbufs, but that seems not to be the >> problem. Here is the output of 'netstat -m' during one of the load >> spikes: > [...] >> So is this message something to worry about? If so, how can I diagnose >> what's happening, and how do I fix it? > > I've seen it ocassionally too. The error message is printed in > /sys/kern/kern_resource.c when the ui_sbsize resource counter goes negative. > There's probably insufficient locking somewhere in the functions that call > chgsbsize. The increment/decrement is done atomically, but the data pointed > to by the "hiwat" argument is read then updated later without an explicit > lock, so if that value changes while the function is executing, it could > cause problems. ui_sbsize is only used by the resource limiting code, > though, so unless you're enforcing an sbsize rlimit, it should be harmless. Thanks for the response ... I'll double-check were we might be setting that kind of limit. Doug -- [^L] Breadth of IT experience, and depth of knowledge in the DNS. Yours for the right price. :) http://SupersetSolutions.com/
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4EE9287F.9060704>