On Wed, 5 Dec 2001, Terry Lambert wrote: > > Alexander, > > I had experienced this problem before. It is most likely that you are running > > out of page table pages. Try changing NKPT in /sys/i386/include/pmap.h to 64. > > That worked for me. > > > > tim > > > > On Wed, Dec 05, 2001 at 03:57:22PM +0300, Varshavchick Alexander wrote: > Date: Wed, 05 Dec 2001 22:02:19 -0800 > From: Terry Lambert <[EMAIL PROTECTED]> > To: Tim Wiess <[EMAIL PROTECTED]> > Cc: Varshavchick Alexander <[EMAIL PROTECTED]>, [EMAIL PROTECTED] > Subject: Re: 4G phisical memory kernel trap > > Tim Wiess wrote: > > > > > Hi, > > > > > > I have a PIII box with 4G phisical memory and FreeBSD 4.2 and it traps > > > while booting - "fatal trap 12 page fault". With less than 4G memory the > > > server is working good. > > He will still se problems under load, if he does this. In particular, > it will lead to panics under load. > > > The primary problem with using 4G is that the KVA space is too > small to use that much memory reasonably, because of the swap maps > that get created in /sys/i386/i386/machdep.c, which are scaled to > 3 times the KVA space. > > In general, the FreeBSD design was to support sparse memory maps, > where the amount of physical RAM did not approach the limits of > the address space. > > I worked around this once by changing the calculation significantly, > so that there was not an overallocation of the mapping tables. > > To be able to put this extra memory to profitable use, you will > need to be able to allocate kernel structures, such as sockets, > mbufs, and open file table entries, tcpcb's and inpcb's in it. > > For this to work, you really MUST address the machdep.c problems.
So how can it be done, are there any patches for machdep.c, or is it solved in 4.4-stable kernel? > > I also suggest increasing the KVA space from 3G to 4G. > You mean setting KVA_SPACE option in kernel config? > Another sugestion is that you should use 4M pages for most of > this memory, if you can figure out how to do it (it's not hard, > but there is some minor intelligence required, since you will > end up getting more trap 12 faults if you aren't careful). The > mere acto of going to 4M pages will save you 4K per 4M of pages > times how many pages you have, or ~4M. You will also get a 4-6% > performance increase, overall, depending on usage patterns. > I'm afraid I can have problems figuring this thing out, can you please give guidelines here? > I really should write an article for Daemon New on the FreeBSD > startup process at boot time, to fill in the gaps behind Matt > Dillon's articles on FreeBSD VM after it has been started up. > I will start work on one. > It will be great! Alexander Varshavchick, Metrocom Joint Stock Company Phone: (812)118-3322, 118-3115(fax) To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
