Need Help in porting Jemalloc.

[RajaKishore Sahu]

Hi Luke,

Thanks for your reply.

I am trying to port Jemalloc to a embedded environment where we have only
40 MB of memory for a subsystem.

While porting I found that in start up it is consuming almost 38 MB of
memory with arena size of 1MB. We spawn around 70 threads in the start up.
So we are only 2 MB left for that subsystem. While the system is in run
definitely it will ask for more memory, in that case how we are going to
satisfy the memory needed by Jemalloc?

Current allocator consumes around 20 - 22 MB of memory and remaining is
used for the system to run.

Or Jemalloc is not suited for embedded environment?

Thanks
Rajakishore


On Tue, Jan 19, 2016 at 9:02 AM, D'Alessandro, Luke K <ldalessa at indiana.edu>
wrote:

>
> > On Jan 17, 2016, at 9:53 PM, RajaKishore Sahu <raju.sahu at gmail.com>
> wrote:
> >
> > Hi,
> >
> > I have a follow up question.
> >
> > We have only 40 MB of memory for our sub system.
> >
> > I start up Jemalloc is keep asking for new chunks and by the time the
> system becomes ready it almost consumes 38 MB of memory.
> >
> > How we can tell Jemalloc to uses already allocated memory chuck when we
> run out of our 40 MB of memory?
>
> I’m not sure this has anything to do with jemalloc. It just allocates
> chunks in response to application demand when it can’t satisfy new
> allocations given its existing chunks. That being said, I don’t know much
> about using jemalloc in constrained environments—we’re using it in 128GB
> settings.
>
> Are you suffering from terrible fragmentation? Is this consistent across
> different allocations? I supposed it’s easily possible that jemalloc needs
> a bunch of memory for its own infrastructure for trees and such.
>
> Luke
>
> >
> > Thanks
> > Rajakishore
> >
> > On Tue, Oct 13, 2015 at 8:21 AM, RajaKishore Sahu <raju.sahu at gmail.com>
> wrote:
> > Hi Luke,
> >
> > Thanks for sharing the details. I will go through the code and come back
> if I need some more help.
> >
> > Thanks
> > Rajakishore Sahu
> >
> > On Mon, Oct 12, 2015 at 5:09 PM, D'Alessandro, Luke K <
> ldalessa at indiana.edu> wrote:
> >
> > > On Oct 12, 2015, at 1:12 AM, RajaKishore Sahu <raju.sahu at gmail.com>
> wrote:
> > >
> > > Hi,
> > >
> > > I am trying to port Jemalloc. We are going to use it for our
> sub-system not for the whole system.
> > >
> > > Main system has its own memory manager. While initializing the
> sub-system (in boot up) we will allocate memory from main system (Ex:- 10
> MB) which will be contiguous memory then we want to give the start address
> and size to Jemalloc to manage it. Please let us know where to provide the
> start address to jemalloc?
> >
> > Hi. This dlmalloc-mspace-like interface isn’t really supported by
> jemalloc, which wants to be able to request “chunks” of memory from the
> system using a chunk allocator (typically mmap()).
> >
> > To do what you want you need to write a chunk provider based on [the
> chunk hooks class](
> http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html),
> and then install it for all of the threads in your code. Your chunk
> provider will have to give jemalloc chunks from your contiguous region.
> >
> > We do this in HPX-5 to manage a network-registered global heap. The
> callback chunks are [here](
> https://gitlab.crest.iu.edu/extreme/hpx/blob/develop/libhpx/gas/pgas/jemalloc_global.c)
> and the “heap” is implemented (here)[
> https://gitlab.crest.iu.edu/extreme/hpx/blob/develop/libhpx/gas/pgas/heap.c].
> This code is slightly complex but it’s basically just using a bitmap to
> allocate chunks from a large contiguous heap, and can serve as an example
> for you.
> >
> > > Main system will provide thread, Mutex/Semaphore and the memory for
> this will not be allocated from the sub-system. In this scenario how can we
> enable thread caching? We do have a rapper to create threads, which means
> we know which are the the threads created by sub-system. Will it help in
> enabling the thread caching?
> >
> > Thread caching will likely be on by default for the threads. In more
> complex code where you might want to manage more than one memory space, you
> may need to explicitly allocate new caches.
> >
> > Luke
> >
> > >
> > > Any help will greatly appreciated!
> > >
> > >
> > > --
> > > Thanx
> > > Rajakishore Sahu
> > > Mail:-raju.sahu at gmail.com
> > > _______________________________________________
> > > jemalloc-discuss mailing list
> > > jemalloc-discuss at canonware.com
> > > http://www.canonware.com/mailman/listinfo/jemalloc-discuss
> >
> >
> >
> >
> > --
> > Thanx
> > Rajakishore Sahu
> > Mail:-raju.sahu at gmail.com
> > Mobile:-+91 9886719841
> >
> >
> >
> > --
> > Thanx
> > Rajakishore Sahu
> > Mail:-raju.sahu at gmail.com
> > Mobile:-+91 9886719841
>
>


-- 
Thanx
Rajakishore Sahu
Mail:-raju.sahu at gmail.com
Mobile:-+91 9886719841
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