Date: Thu, 1 Dec 2011 15:16:18 -0000 From: "Steven Hartland" <killing@multiplay.co.uk> To: "RW" <rwmaillists@googlemail.com>, <freebsd-hackers@freebsd.org> Subject: Re: Invalid memory stats from vmstat and sysctl vm.vmtotal? Message-ID: <8F2B03B67CBD4E83BB84761D8EF331B6@multiplay.co.uk> References: <547298A3C38F407887E1AAAAC487DF6D@multiplay.co.uk> <20111201135818.641625c5@gumby.homeunix.com>
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----- Original Message -----
From: "RW" <rwmaillists@googlemail.com>
To: <freebsd-hackers@freebsd.org>
Sent: Thursday, December 01, 2011 1:58 PM
Subject: Re: Invalid memory stats from vmstat and sysctl vm.vmtotal?
> On Wed, 30 Nov 2011 12:39:10 -0000
> Steven Hartland wrote:
>
>> We're seeing some impossible memory usage stats reported on machines
>> here from vmstat and sysctl vm.vmtotal.
>>
>> We have machines reporting to be using 31GB total when they only have
>> 8GB physical and are not using any swap.
>>
>> Here's an output from one of our machines:-
>> vmstat -c 2 -w 1 -n 0
>> procs memory page faults cpu
>> r b w avm fre flt re pi po fr sr in sy cs us
>> sy id 0 0 0 31768M 2112M 586 0 0 0 421 0 106 270
>> 569 0 6 94 0 0 0 31768M 2112M 2 0 0 0 0 0 370
>> 8139 3996 0 1 99
>>
>> ...
>> It looks like it may be out by a factor of 4, possibly due to the fact
>> the its a 4k page size not 1k as indicated by the vmstat man page:-
>>
>
> I don't think so, I have 16GB and tops shows:
>
> Mem: 817M Active, 396M Inact, 1364M Wired, 82M Cache, 1282M Buf, 13G
> Free
>
> but
>
> vmstat -c 2 -w 1 -n 0
> procs memory page faults cpu
> r b w avm fre flt re pi po fr sr in sy cs us sy
> id 0 0 0 9750M 13G 450 5 3 1 560 0 234 50201 5206 2
> 2 96 1 0 0 9742M 13G 79 4 0 0 573 0 239 51886 4700
> 0 1 99
Hmm, yes on another machine same OS with 16GB memory we see:-
dmesg | grep memory
real memory = 17179869184 (16384 MB)
avail memory = 16536604672 (15770 MB)
vmstat -c 2 -w 1 -n 0
procs memory page faults cpu
r b w avm fre flt re pi po fr sr in sy cs us sy id
0 0 0 1948M 666M 395 14 0 0 398 1966 3237 5980 14085 2 4 93
1 0 0 1948M 636M 4 0 0 0 16 0 8215 18660 35322 2 7 92
sysctl vm.vmtotal
vm.vmtotal:
System wide totals computed every five seconds: (values in kilobytes)
===============================================
Processes: (RUNQ: 1 Disk Wait: 0 Page Wait: 0 Sleep: 194)
Virtual Memory: (Total: 1075975332K Active: 1979056K)
Real Memory: (Total: 309048K Active: 160804K)
Shared Virtual Memory: (Total: 75112K Active: 18860K)
Shared Real Memory: (Total: 15656K Active: 10572K)
Free Memory Pages: 731960K
but with top:-
last pid: 38187; load averages: 0.15, 0.16, 0.16 up 2+23:33:55 15:13:02
195 processes: 1 running, 194 sleeping
CPU: 0.0% user, 0.0% nice, 4.1% system, 0.0% interrupt, 95.9% idle
Mem: 886M Active, 12G Inact, 2194M Wired, 599M Cache, 1630M Buf, 138M Free
Swap: 8192M Total, 1512K Used, 8190M Free
So I've no idea whats going on?
Regards
Steve
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