[PATCH] libcsupport: Have greedy allocations use consume extended memory
Chris Johns
chrisj at rtems.org
Mon Feb 8 21:00:04 UTC 2021
On 9/2/21 12:37 am, Joel Sherrill wrote:
> On Mon, Feb 8, 2021 at 12:44 AM Chris Johns <chrisj at rtems.org
> <mailto:chrisj at rtems.org>> wrote:
>
> On 8/2/21 5:38 pm, Sebastian Huber wrote:
> >
> > On 08/02/2021 07:30, chrisj at rtems.org <mailto:chrisj at rtems.org> wrote:
> >> diff --git a/cpukit/libcsupport/src/rtems_heap_greedy.c
> >> b/cpukit/libcsupport/src/rtems_heap_greedy.c
> >> index 4dda39873f..2361f17d2e 100644
> >> --- a/cpukit/libcsupport/src/rtems_heap_greedy.c
> >> +++ b/cpukit/libcsupport/src/rtems_heap_greedy.c
> >> @@ -30,8 +30,20 @@ void *rtems_heap_greedy_allocate(
> >> size_t block_count
> >> )
> >> {
> >> + Heap_Control *heap = RTEMS_Malloc_Heap;
> >> + size_t size = 128 * 1024 * 1024;
> >> void *opaque;
> >> + while (size > 0) {
> >> + opaque = (*rtems_malloc_extend_handler)( heap, size );
> >> + if (opaque == NULL) {
> >> + size >>= 1;
> >> + } else {
> >> + if ( rtems_malloc_dirty_helper != NULL )
> >> + (*rtems_malloc_dirty_helper)( opaque, size );
> >> + }
> >> + }
> > You need a couple of more ' ' after and before the braces. Each if should
> have a
> > { }. Apart from the formatting it looks good.
>
> Thanks, I will fix the formatting and push.
>
> And there is no performance issue on hardware so that must be a psim thing.
>
>
> What performance issue do you think there could have been?
I do not know. I have never looked at how psim is implemented. I believe the
slow down inside the simulator.
> This must just be a side-effect of the PowerPC BSPs which have more than 32MB
> RAM and want to support dynamically loading code. They must ensure that no
> branches or calls exceed 32MB from the current location. Thus it has to be loaded
> early in program life before the heap is extended.
This is inside the simulator?
> Are there other supported architectures where code must fit into a subset of the
> address space where it could negatively impact dynamic loading?
ARM.
> How does the DL code deal with PPC code that is built without the -mlongcall
> option?
libdl adds a trampoline ...
https://git.rtems.org/rtems/tree/cpukit/libdl/rtl-mdreloc-powerpc.c#n184
Chris
> EPICS discusses this here:
>
> https://epics.anl.gov/base/ppc.php <https://epics.anl.gov/base/ppc.php>
>
> --joel
>
>
> Chris
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