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Re: where is my memory?
On Wed, Sep 22, 2010 at 10:57 AM, matthew sporleder
> On Wed, Sep 22, 2010 at 9:18 AM, Johnny Billquist <bqt%softjar.se@localhost>
>> der Mouse wrote:
>>>>>> total memory = 2047 MB
>>>>>> avail memory = 1999 MB
>>>>> total memory = 256 MB
>>>>> avail memory = 239 MB
>>>> Some graphics chips, especially on lower-end machines, use main
>>>> memory, thus making it unavailable to the CPU.
>>> It's not that simple. I've seen this for a very long time, including
>>> on machines with no graphics chips at all, such as 4.3 on a VAX 750.
>>> Here's a live example; this is quoted from /var/run/dmesg.boot on a
>>> SPARCstation LX that's my desktop at one of my workplaces:
>>> total memory = 48688 KB
>>> avail memory = 41676 KB
>>> That's with a cg6 with its own private framebuffer RAM.
>> Well, for VAXen, the difference between total memory, and available
>> memory is:
>> format_bytes(pbuf, sizeof(pbuf), avail_end);
>> printf("total memory = %s\n", pbuf);
>> panicstr = NULL;
>> mtpr(AST_NO, PR_ASTLVL);
>> #if VAX46 || VAX48 || VAX49 || VAX53 || VAXANY
>> minaddr = 0;
>> * Allocate a submap for physio. This map effectively limits the
>> * number of processes doing physio at any one time.
>> phys_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr,
>> VM_PHYS_SIZE, 0, false, NULL);
>> format_bytes(pbuf, sizeof(pbuf), ptoa(uvmexp.free));
>> printf("avail memory = %s\n", pbuf);
>> So, obviously a malloc for physio... :-)
>> Don't know about any other ports, but the code is there for the
> So in x86 land this is the *_init() functions from
> src/sys/kern/init_main.c? Is it just the functions that come before
This is, at least, where some of the avail and total numbers come
from. I added a custom kernel to watch the memory during the boot and
total memory = 255MB
avail memory = 238 MB <- after consinit
avail memory = 237 MB <- after uvm_init
avail memory = 235 MB <- after a bunch of devices startup
avail memory = 234 MB <- final number
Does vmstat -m mention any of this stuff?
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