Re: Warning: Pentium 4 CPU: PSE disabled

PSE allows you to map 4MB of memory into a single page table entry 
instead of just 4KB.  This is good when you have a lot of data that
operates in the same address space and doesn't need to be swapped out
to disk.  It's also more efficient for the CPU since only one TLB cache
entry is needed for the 4MB chunk instead of 1024 4KB entries.  Where
this comes in really handy is with mapping the kernel onto a single
4MB PSE page, since you know that it will never be swapped out and you
don't want to pollute the 4KB TLB cache with kernel page entries.  So,
consider it an optimization, but not a requirement for operation.

Scott

Wilkinson, Alex wrote:
> John, what is the benefit of Page Size Extensions ?
> 
>  - aW
> 
> 	0n Mon, Nov 15, 2004 at 04:14:21PM -0500, John Baldwin wrote: 
> 
> 	On Monday 15 November 2004 11:17 am, Kaspars wrote:
> 	> Hi all,
> 	>
> 	>  I just installed new pc with FreeBSD 4.10 and updated to FreeBSD
> 	> 4.10-RELEASE-p3 and found in dmesg:
> 	> CPU: Intel(R) Pentium(R) 4 CPU 2.40GHz (2411.60-MHz 686-class CPU)
> 	>   Origin = "GenuineIntel"  Id = 0xf29  Stepping = 9
> 	> Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MC
> 	>A,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
> 	> Hyperthreading: 2 logical CPUs
> 	> real memory  = 520028160 (507840K bytes)
> 	> avail memory = 502751232 (490968K bytes)
> 	> Preloaded elf kernel "kernel" at 0xc0329000.
> 	> Warning: Pentium 4 CPU: PSE disabled
> 	> Pentium Pro MTRR support enabled
> 	> md0: Malloc disk
> 	>
> 	> Tryed to google, tryed in ircnet #freebsd but nobody can`t say what
> 	> realy wrong :)
> 	
> 	There is a bug in how some of the Pentium4 chips handle PSE that 5.x works 
> 	around already.  However, the fix was too large to backport to 4.x, so 
> 	instead the PSE feature is turned off in 4.x.  I wouldn't worry about it, 
> 	your machine will still work fine without PSE.
> 	
> 	-- 
> 	John Baldwin <jhb_at_FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
> 	"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org
> 	_______________________________________________
> 	freebsd-current_at_freebsd.org mailing list
> 	http://lists.freebsd.org/mailman/listinfo/freebsd-current
> 	To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org"
> 	
> _______________________________________________
> freebsd-current_at_freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-current
> To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org"