Re: (panic) Lots of network memory needed

dave baukus Wed, 15 Jun 2005 11:57:26 -0700

I'm fairly sure that you are out of kernel virtual memory.
Look at kern/kern_malloc.c kmeminit (); you can play w/ VM_KMEM_SIZE_MAX
or  TUNABLE_INT_FETCH("kern.vm.kmem.size", &vm_kmem_size);


     /*
         * Try to auto-tune the kernel memory size, so that it is
         * more applicable for a wider range of machine sizes.
         * On an X86, a VM_KMEM_SIZE_SCALE value of 4 is good, while
         * a VM_KMEM_SIZE of 12MB is a fair compromise.  The
         * VM_KMEM_SIZE_MAX is dependent on the maximum KVA space
         * available, and on an X86 with a total KVA space of 256MB,
         * try to keep VM_KMEM_SIZE_MAX at 80MB or below.
         *
         * Note that the kmem_map is also used by the zone allocator,
         * so make sure that there is enough space.
         */
        vm_kmem_size = VM_KMEM_SIZE;
        mem_size = cnt.v_page_count * PAGE_SIZE;

#if defined(VM_KMEM_SIZE_SCALE)
        if ((mem_size / VM_KMEM_SIZE_SCALE) > vm_kmem_size)
                vm_kmem_size = mem_size / VM_KMEM_SIZE_SCALE;
#endif

#if defined(VM_KMEM_SIZE_MAX)
        if (vm_kmem_size >= VM_KMEM_SIZE_MAX)
                vm_kmem_size = VM_KMEM_SIZE_MAX;
#endif

        /* Allow final override from the kernel environment */
        TUNABLE_INT_FETCH("kern.vm.kmem.size", &vm_kmem_size);


Karim Fodil-Lemelin wrote:

Thanks but the system still crashes (FreeBSD 4.9) with 131072. Here is abacktrace showing just that:


Debugger (msg=0xc02b6cdb "panic") at ../../i386/i386/db_interface.c:321
321     }
(kgdb) bt
#0  Debugger (msg=0xc02b6cdb "panic") at ../../i386/i386/db_interface.c:321
#1  0xc016a230 in panic (

fmt=0xc02ea380 "pmap_enter: invalid page directory pdir=%#llx,va=%#x\n")

   at ../../kern/kern_shutdown.c:593
#2  0xc0283594 in pmap_enter (pmap=0xc0340460, va=4292141056, m=0xc24b2848,
   prot=7 '\a', wired=1) at ../../i386/i386/pmap.c:1943
#3  0xc023ddd0 in vm_fault (map=0xc033322c, vaddr=4292141056,
   fault_type=7 '\a', fault_flags=1) at ../../vm/vm_fault.c:841
#4  0xc023df0a in vm_fault_wire (map=0xc033322c, start=4292141056,
   end=4292149248) at ../../vm/vm_fault.c:915
#5  0xc0240831 in vm_map_pageable (map=0xc033322c, start=4292141056,
   real_end=4292149248, new_pageable=0) at ../../vm/vm_map.c:1817
#6  0xc023ea25 in kmem_alloc (map=0xc033322c, size=8192)
   at ../../vm/vm_kern.c:213
#7  0xc024a46f in _zget (z=0xdb5c6e80) at ../../vm/vm_zone.c:425
#8  0xc024a269 in zalloc (z=0xdb5c6e80) at ../../vm/vm_zone.c:60
#9  0xc0196106 in namei (ndp=0xfa489ef4) at ../../kern/vfs_lookup.c:104
#10 0xc01614ca in execve (p=0xfa482e00, uap=0xfa489f90)
   at ../../kern/kern_exec.c:165
#11 0xc01590a1 in start_init (dummy=0x0) at ../../kern/init_main.c:543
(kgdb) p nmbclusters
$1 = 131072
(kgdb)

Goran Spirovski - MorEl On.net wrote:

AFAIK the number of mbufs (and consequently nmbclusters) has to be apower

of 2, so you should set it to 131072

MorEl

----- Original Message ----- From: "Karim Fodil-Lemelin" <[EMAIL PROTECTED]>
To: <freebsd-net@freebsd.org>
Sent: Wednesday, June 15, 2005 6:08 PM
Subject: (panic) Lots of network memory needed

Hello,

From kernel tuning page

(http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-kern

el-limits.html)

Some sentence about nmbclusters says:

"Under no circumstances should you specify an arbitrarily high value for


this parameter as it could lead to a boot time crash."

Now I want to push the limits where I need 4KB buffer for each of the


32000 connections I want this server to handle. If I do the math:

(32000 (conns) * 4 (KB/buffer) * 2 (buffer/conn)) / 2048 (KB/cluster)

= 128000 clusters

So I set this arbitrary high value in loader.conf under

(kern.ipc.nmbclusters) and no surprises I get panic: pmap_enterinvalid page

directory pdir=0x3cb063, va=0xfff800

(va has a weird address here)

I know I am pushing the limits here but I have plenty of memory (2GB) on


this system (after all its just 250MB for network memory ;) and this is
mainly just experimentation.

I would like some pointers toward fixing this. Is there another variable

tied into this (I guess so)? Could anybody points me to a technicaldocument

that would explain the relationship with that (those) other(s) presumed
variable(s)?

Thank you,


Karim


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--
Dave Baukus
[EMAIL PROTECTED]                       
        Chiaro Networks Ltd.
        Richardson, Texas
        USA

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