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Operating Systems AIX Check that memory page is filled by zeros when a process gets it in first time Post 302370619 by sokolovm on Friday 13th of November 2009 02:01:08 AM
Old 11-13-2009
Check that memory page is filled by zeros when a process gets it in first time

I have to check whether AIX fills physical memory pages by zeros when they are given for a new process (or may be when they are freed from an address space, but it's hardly probable).

In other words when a process gets a new memory page, this one must be cleaned.

I've solved this issue for Solaris using DTrace.
I found out that in Solaris memory pages are cleaned by pagezero routine.
So using entry and return probes of fbt provider in DTrace and getting input and output of the functions which are used in pagezero implementation I achieved my goal.

And now I have to solve the same task in AIX.
As I understand the source code of AIX is closed and that way which was used in Solaris isn't fit.

First of all could you tell me how can I translate the virtual address which was gotten from malloc to the physical address?

I thought it's possible to do using kdb and its tr command.
But when I type the next command in kdb:
(0)> tr 0x20001878
i get the next result:
WARNING: 0000000020001878 invalid sid
where 0x20001878 is the address which was gotten from malloc, and sid - segment identifier.
May be it's because the main purpose of kdb is debugging of kernel extension and my actions are wrong?

My system: AIX 6.1 powerpc

---------- Post updated 11-13-09 at 04:01 PM ---------- Previous update was 11-12-09 at 04:56 PM ----------

Ok. One more question.
How can I get dump of whole computer's main memory (physical memory)?
Does AIX include some utility like memdump?
 

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profile(7D)							      Devices							       profile(7D)

NAME
profile - DTrace profile interrupt provider DESCRIPTION
The profile driver is a DTrace dynamic tracing provider that adds time-based interrupt event sources that can be used as DTrace probes. Each profile event source is a time-based interrupt firing every fixed, specified time interval. You can use these probes to sample some aspect of system state every unit time and the samples can then be used to infer system behavior. If the sampling rate is high, or the sam- pling time is long, an accurate inference is possible. By using the DTrace facility to bind arbitrary actions to probes, you can use the profile provider to sample practically anything in the system. For example, you could sample the state of the current thread, the CPU state, or the current machine instruction each time a probe fires. The profile driver is not a public interface and you access the instrumentation offered by this provider through DTrace. Refer to the Solaris Dynamic Tracing Guide for a description of the public documented interfaces available for the DTrace facility and the probes offered by the profile provider. ATTRIBUTES
See attributes(5) for a description of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWdtrp | +-----------------------------+-----------------------------+ |Interface Stability |Private | +-----------------------------+-----------------------------+ SEE ALSO
dtrace(1M), attributes(5), dtrace(7D) Solaris Dynamic Tracing Guide SunOS 5.11 4 Sep 2003 profile(7D)
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