Memory Map Files

Steve Grimm sgrimm at facebook.com
Thu Jul 5 03:00:48 UTC 2007


Yes, thanks, I think we all know what memory-mapped files are! Do you hope
to gain:

* Bigger cache sizes by mapping a file bigger than physical memory?
* Caches that persist across restarts?
* Caches that you can share among concurrently running memcached processes
by pointing them at the same file?
* Caches that can be directly accessed by client applications by pointing
them at the file maintained by memcached?
* Caches that can be accessed remotely using a network filesystem?
* Administrative benefits (e.g., setting the cache size by changing the file
size)? 
* Performance benefits?

Hopefully that list makes it clear that ³What do you hope to gain?² is not
an idiotic question. You could be looking for any or all of those things.
What feature(s), specifically, do you want to have that memcached as it
currently exists doesn¹t provide? Are you looking specifically for one of
the above benefits, some combination of them, or something else entirely?

-Steve


On 7/4/07 7:43 PM, "Joel Poloney" <jpoloney at gmail.com> wrote:

> ... do I really need to explain this one? I thought memory mapped files were
> pretty self explanatory. See wikipedia:
> http://en.wikipedia.org/wiki/Memory-mapped_file
> <http://en.wikipedia.org/wiki/Memory-mapped_file> .
> 
> Yes, I know there are drawbacks, but if implemented correctly, the benefits
> far outweigh them.
> 
> -- Joel
> 
> On 7/5/07, Steve Grimm < sgrimm at facebook.com <mailto:sgrimm at facebook.com> >
> wrote:
>> What do you hope to gain by doing that?
>> 
>> -Steve
>> 
>> 
>> 
>> On 7/4/07 5:26 AM, "Joel Poloney" <jpoloney at gmail.com> wrote:
>> 
>>> Hello list,
>>> 
>>> I was curious if it was possible to extend memcached to memory map files as
>>> well. I know there are other memory management systems out there that do
>>> this, but I would like to use only 1 memory management system if possible.
>>> Memcached already deals with memory... so technically this should be
>>> possible... but is it easy to do, I'm not sure.
>>> 
>>> Thanks!
>>> 
>>> -- Joel
>>> 
>> 
> 
> 


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