Date: Thu, 17 Aug 2000 21:34:46 -0400 From: Xiaowei Yang <yxw@cordelia.lcs.mit.edu> To: Bosko Milekic <bmilekic@dsuper.net> Cc: Xiaowei Yang <yxw@MIT.EDU>, freebsd-net@FreeBSD.ORG Subject: Re: how to set nmbufs Message-ID: <200008180134.VAA21308@cordelia.lcs.mit.edu> In-Reply-To: Message from Bosko Milekic <bmilekic@dsuper.net> of "Thu, 17 Aug 2000 16:39:44 EDT." <Pine.BSF.4.21.0008171636010.4947-100000@jehovah.technokratis.com>
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Hi,
Thanks a lot for the reply. I guess I sould phrase my question like
this: I am doing some network simulation which requires a lot mbufs
(for packet headers) but not mclusters. I want to allocate as much
memory as possible. For example, I need about 1M mbufs. I am using
right way to do this? I am using FreeBSD 4.0-release. I set
NMBCLUSTER to be 64000.
Here is 'netstat -m' output before the page fault happened:
5948/256000/256000 mbufs in use (current/peak/max):
5942 mbufs allocated to data
6 mbufs allocated to packet headers
178/302/64000 mbuf clusters in use (current/peak/max)
32604 Kbytes allocated to network (3% in use)
102535 requests for memory denied
0 requests for memory delayed
0 calls to protocol drain routines
Here is the trace:
ether_output+0x30b
ip_output+0x5cb
ip_stripoptions+0x1e8
ip_input+0x46a
ip_input+0x69f
doreti_popl_fs_fault+0x95
Xintr11+0x65
I tried a larger value for NMBCLUSTER , which is 262144, but the
kernel stopped booting with page fault. (I heard that the size of mbuf
is 256 in 4.x. But I still see MSIZE is set to 128 in
sys/i386/include/param.h, which I donot understand.)
Thanks,
>
> Hi,
>
> I'm afraid you'll need to provide much more information concerning
> the page fault, if you expect someone to be able to help you.
> In particular, the following is the necessary minimum:
>
> * FreeBSD version you're doing this with.
> * Is this reproducable? If so, what is the exact procedure?
> * Stack trace, as well as other available debugging information
> following the page fault.
>
> With the information you have presently provided, it may not even be
> the relevant code that is causing this fault. It could just be triggering
> a problem that occurs only when kmem_map is mostly occupied by the mb_map
> submap, and the size of the kmem_map (or its parent, kernel_map), may
> need to be increased.
>
> Bosko
> bmilekic@dsuper.net
>
> On Thu, 17 Aug 2000, Xiaowei Yang wrote:
>
> > Greetings, everyone,
> >
> > I am doing some simulation that needs to allocate as many nmbufs as
> > possible. I could not figure out how to set nmbufs to be the maximum
> > value allowd by my physical memory. I tired to mannual set it to be a
> > huge number, for example, 128MB/128B=1M (I have 196M memory) and used
> > netstat -m to monitor the real allocated nmbufs. However, when it
> > reached some value lower that a 1M, a kernel page fault happened.
> >
> > It seems to me I also need to increase the maximum kernel memory size
> > seperately. Can someone tell me how to do it right? Is there a simple
> > formula to estimate the number?
> >
> >
> > Thanks,
> >
> > Xiaowei
> >
>
Cheers,
--Xiaowei
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