Re: MAXPHYS and physical memory (Was: Re: siis/atacam/ata/gmirror 8.0-BETA3 disk performance)

Mel Flynn wrote:
On Wednesday 02 September 2009 16:51:35 Alexander Motin wrote:

For maximum linear I/O performance you may want to build kernel with
options MAXPHYS=(1024*1024)

I've found that just doubling the default MAXPHYS already panics-on-boot a 1.5GB i386 system. Is there any reasonable conversion table for MAXPHYS to physical memory, since various memory related kernel setups are derived from or calculated with MAXPHYS?

What especially your panic was about? It could be bug in ATA(4) or some other code, that does not handle MAXPHYS correctly. I don't think that you could reach memory limit during simple system boot because of that. I am successfully running my testing Pentium-75 with 64MB RAM with 1MB MAXPHYS.

Could you show your panic message?

--
Alexander Motin
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