Date: Thu, 13 May 2004 14:02:21 -0700 (PDT) From: Stefan Bethke <stb@lassitu.de> To: freebsd-gnats-submit@FreeBSD.org Subject: docs/66621: Document fix for "kmem_map too small panics" Message-ID: <200405132102.i4DL2LVj006272@www.freebsd.org> Resent-Message-ID: <200405132110.i4DLALFr069104@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
>Number: 66621
>Category: docs
>Synopsis: Document fix for "kmem_map too small panics"
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-doc
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: update
>Submitter-Id: current-users
>Arrival-Date: Thu May 13 14:10:21 PDT 2004
>Closed-Date:
>Last-Modified:
>Originator: Stefan Bethke
>Release: 5-current
>Organization:
>Environment:
FreeBSD majestix.tallence.de 5.2-CURRENT FreeBSD 5.2-CURRENT #5: Wed May 12 12:47:06 GMT 2004 root@majestix.tallence.de:/usr/obj/usr/src/sys/MAJESTIX i386
>Description:
solution to "kmem_map too small" panics have been requested at least 5 times on -current in the past two months; fix is simple to implement, but hard to find :-)
Kris Kennaway graciously provided advice to limit VM_KMEM_SIZE_MAX to 400 MB; that seems to be working for everybody who enquired.
>How-To-Repeat:
>Fix:
Index: book.sgml
===================================================================
RCS file: /home/ncvs/doc/en_US.ISO8859-1/books/faq/book.sgml,v
retrieving revision 1.618
diff -u -C10 -r1.618 book.sgml
cvs diff: conflicting specifications of output style
*** book.sgml 11 May 2004 13:29:47 -0000 1.618
--- book.sgml 13 May 2004 20:55:09 -0000
***************
*** 3082,3101 ****
--- 3082,3125 ----
<question id="asusk7v-boot-failure">
<para>The boot floppy hangs on a system with an ASUS K7V
motherboard. How do I fix this?</para>
</question>
<answer>
<para>Go into the BIOS setup and disable the <quote>boot virus
protection</quote>.</para>
</answer>
</qandaentry>
+
+ <qandaentry>
+ <question id="kmem-map-too-small">
+ <para>My system has more than 1 GB of RAM, and I'm getting panics
+ with <quote>kmem_map too small</quote> messages. What is
+ wrong?</para>
+ </question>
+
+ <answer>
+ <para>Normally, FreeBSD determines a number of kernel parameters,
+ such as the maximum number of open files that can be opened
+ concurrently, from the amount of memory installed in the
+ system. On systems with one gigabyte of RAM or more, this
+ <quote>auto-sizing</quote> mechanism may choose values that are
+ too large, leading to poor performance, or even to
+ panics.</para>
+ <para>In this particular case, the kernel memory allocation map
+ is too small for the amount of memory the kernel believes it
+ should be able to allocate, hence the panic. Compile your own
+ kernel, and add the <option>VM_KMEM_SIZE_MAX</option> to your
+ kernel configuration file. Limiting the maximum size to 400 MB
+ (<option>VM_KMEM_SIZE_MAX 419430400</option>). </para>
+ </answer>
+ </qandaentry>
</qandaset>
</chapter>
<chapter id="troubleshoot">
<title>Troubleshooting</title>
<qandaset>
<qandaentry>
<question id="awre">
<para>What do I do when I have bad blocks on my hard drive?</para>
>Release-Note:
>Audit-Trail:
>Unformatted:
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200405132102.i4DL2LVj006272>