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core: prefer RAM allocation in high memory

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We preserve lower RAM for device drivers with physical memory
constraints. If no physical RAM constraint exists, the allocations above
3G (32-bit) or 4G (64-bit) are preferred.
This commit is contained in:
Alexander Boettcher 2016-11-10 15:08:08 +01:00 committed by Christian Helmuth
parent 57949c2bbb
commit 81f0cacf66
1 changed files with 29 additions and 6 deletions
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35
repos/base/src/core/ram_session_component.cc
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@ -142,11 +142,32 @@ Ram_dataspace_capability Ram_session_component::alloc(size_t ds_size, Cache_attr
*/
void *ds_addr = 0;
bool alloc_succeeded = false;
for (size_t align_log2 = log2(ds_size); align_log2 >= 12; align_log2--) {
if (_ram_alloc->alloc_aligned(ds_size, &ds_addr, align_log2,
_phys_start, _phys_end).ok()) {
alloc_succeeded = true;
break;
/*
* If no physical constraint exists, try to allocate physical memory at
* high locations (3G for 32-bit / 4G for 64-bit platforms) in order to
* preserve lower physical regions for device drivers, which may have DMA
* constraints.
*/
if (_phys_start == 0 && _phys_end == ~0UL) {
addr_t const high_start = (sizeof(void *) == 4 ? 3UL : 4UL) << 30;
for (size_t align_log2 = log2(ds_size); align_log2 >= 12; align_log2--) {
if (_ram_alloc->alloc_aligned(ds_size, &ds_addr, align_log2,
high_start, _phys_end).ok()) {
alloc_succeeded = true;
break;
}
}
}
/* apply constraints or re-try because higher memory allocation failed */
if (!alloc_succeeded) {
for (size_t align_log2 = log2(ds_size); align_log2 >= 12; align_log2--) {
if (_ram_alloc->alloc_aligned(ds_size, &ds_addr, align_log2,
_phys_start, _phys_end).ok()) {
alloc_succeeded = true;
break;
}
}
}
@ -157,7 +178,9 @@ Ram_dataspace_capability Ram_session_component::alloc(size_t ds_size, Cache_attr
* fragmentation could cause a failing allocation.
*/
if (!alloc_succeeded) {
error("out of physical memory while allocating ", ds_size, " bytes");
error("out of physical memory while allocating ", ds_size, " bytes ",
"in range [", Hex(_phys_start), "-", Hex(_phys_end), "] - label ",
Cstring(_label));
throw Quota_exceeded();
}