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sel4: improve allocation in initial_untyped_pool 

Required to boot on hardware. The fragmentation is such unfortunate with the
old allocator that alloc() will throw an exception during very early core boot
phase.

Issue #2044
This commit is contained in:
Alexander Boettcher 2016-07-22 15:50:03 +02:00 committed by Christian Helmuth
parent 356e6498b6
commit b57c33159f
1 changed files with 51 additions and 22 deletions
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73
repos/base-sel4/src/core/include/initial_untyped_pool.h
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@ -65,6 +65,26 @@ class Genode::Initial_untyped_pool
{ }
};
private:
/**
* Calculate free index after allocation
*/
addr_t _align_offset(Range &range, size_t size_log2)
{
/*
* The seL4 kernel naturally aligns allocations within untuped
* memory ranges. So we have to apply the same policy to our
* shadow version of the kernel's 'FreeIndex'.
*/
addr_t const aligned_free_offset = align_addr(range.free_offset,
size_log2);
return aligned_free_offset + (1 << size_log2);
}
public:
/**
* Apply functor to each untyped memory range
*
@ -105,38 +125,47 @@ class Genode::Initial_untyped_pool
*/
for_each_range([&] (Range &range) {
if (sel != UNKNOWN)
return;
/*
* The seL4 kernel naturally aligns allocations within untuped
* memory ranges. So we have to apply the same policy to our
* shadow version of the kernel's 'FreeIndex'.
*/
addr_t const aligned_free_offset = align_addr(range.free_offset, size_log2);
/* calculate free index after allocation */
addr_t const new_free_offset = aligned_free_offset + (1 << size_log2);
addr_t const new_free_offset = _align_offset(range, size_log2);
/* check if allocation fits within current untyped memory range */
if (new_free_offset <= range.size) {
if (new_free_offset > range.size)
return;
/*
* We found a matching range, consume 'size' and report the
* selector. The returned selector is used by the caller
* of 'alloc' to perform the actual kernel-object creation.
*/
range.free_offset = new_free_offset;
/* return selector is matching range */
if (sel == UNKNOWN) {
sel = range.sel;
return;
}
/* check which range is smaller - take that */
addr_t const rest = range.size - new_free_offset;
Range best_fit(*this, sel);
addr_t const new_free_offset_best = _align_offset(best_fit, size_log2);
addr_t const rest_best = best_fit.size - new_free_offset_best;
if (rest_best >= rest)
/* current range fits better then best range */
sel = range.sel;
});
if (sel == UNKNOWN)
if (sel == UNKNOWN) {
warning("Initial_untyped_pool exhausted");
throw Initial_untyped_pool_exhausted();
}
return sel;
Range best_fit(*this, sel);
addr_t const new_free_offset = _align_offset(best_fit, size_log2);
ASSERT(new_free_offset <= best_fit.size);
/*
* We found a matching range, consume 'size' and report the
* selector. The returned selector is used by the caller
* of 'alloc' to perform the actual kernel-object creation.
*/
best_fit.free_offset = new_free_offset;
return best_fit.sel;
}
/**