× The internal search function is temporarily non-functional. The current search engine is no longer viable and we are researching alternatives.
As a stop gap measure, we are using Google's custom search engine service.
If you know of an easy to use, open source, search engine ... please contact support@midrange.com.



Might I ask, why do you "care" how the mmap() API works?  Is it not enough
to know the purpose of the API, the parameters (the interface), and the results
that it provides, in order to make good use of this facility?
 
If you really want to know how a particular mmap works, you can always look
at the source code for any Linux kernel to see how it is implemented.  In effect,
they manipulate the page tables to "map" the contents of the file into the virtual
address space of the running process.
 
Since OS/400 is vastly different, primarily because there are no separate
address spaces "per process", but instead, there is a single large address space,
the so-called "single level store", we can speculate that, somehow, OS/400 would
implement mmap() as follows: it would first create a teraspace into which to
"map" the contents of the file, and then, somehow, set up the corresponding
page table entries to map the relevant data. Now, again, not knowing exactly
how this is implemented "under the covers", this could mean that OS/400 must
also set up the page tables so that, upon "first reference" to each page of data,
the appropriate data from the actual underlying file can be copied into the relevant
pages in virtual storage, etc.  Also, I do not know if this mmap() API can work
with the old "DB2" file system (aka. the QSYS file system files).  Since it is a
"Unix" API, it probably only works for IFS stream files.
 
I hope that helps...
 
Again, why do you "care" about "how it works" versus "what it does" for you?
 
Regards,
 
Mark S. Waterbury
----- Original Message -----
Sent: Tuesday, May 22, 2001 11:12 AM
Subject: Re: how does mmap() work?

 

 
Are teraspaces implemented the same way?
 
====> we are still waiting for Alexei to tell us how.
MY guess: we won't get any info.
 
I think he said he did not know.  I hope he or someone else can tell us who does know.
 
 

As an Amazon Associate we earn from qualifying purchases.

This thread ...

Follow-Ups:
Replies:

Follow On AppleNews
Return to Archive home page | Return to MIDRANGE.COM home page

This mailing list archive is Copyright 1997-2024 by midrange.com and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].

Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.