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Changeset e5a015b in mainline for kernel/generic/src/mm/as.c


Ignore:
Timestamp:
2011-04-16T20:45:36Z (11 years ago)
Author:
Jakub Jermar <jakub@…>
Branches:
lfn, master
Children:
a7dbd49
Parents:
b2fb47f (diff), 9e953bda (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.
Message:

Merge the memory reservation feature (Phase 1) from
lp:~jakub/helenos/mm.

This merge makes the testcase from ticket #114 non-reproducible. The
testcase is now available as tester's malloc2 test. It also seems to me
that this merge makes it harder for the system to run out of memory
during kconsole 'test *' and 'tester *', even though I did see several
hangs already with this feature in place. See below for what is still
missing to make the hangs even less probable or even impossible.

In Phase 1, I am targeting just the low-hanging fruits. In particular,
only anonymous and ELF backend pages are reserved physical memory at
time of as_area_create() and as_area_resize(). Memory is unreserved on
as_area_destroy(). In all other cases, memory is reserved at the same
time as it is allocated, making those calls subject to infinite
blocking if FRAME_ATOMIC is not used.

Possible sources of memory overcommit not addressed in this merge:

  • As mentioned above, only backend pages are reserved; pages for supporting structures such as B+tree nodes, TTEs are not reserved or handled otherwise. Kernel heap allocator fragmentation is not included in the reservations either.
  • The initial amount of reservable memory is fed from zone_construct(). Zone merging is not taken into account, which can make the reservable memory tracking inaccurate.
File:
1 edited

Legend:

Unmodified
Added
Removed
  • kernel/generic/src/mm/as.c

    rb2fb47f re5a015b  
    8080#include <arch/interrupt.h>
    8181
    82 #ifdef CONFIG_VIRT_IDX_DCACHE
    83 #include <arch/mm/cache.h>
    84 #endif /* CONFIG_VIRT_IDX_DCACHE */
    85 
    8682/**
    8783 * Each architecture decides what functions will be used to carry out
     
    447443        else
    448444                memsetb(&area->backend_data, sizeof(area->backend_data), 0);
     445       
     446        if (area->backend && area->backend->create) {
     447                if (!area->backend->create(area)) {
     448                        free(area);
     449                        mutex_unlock(&as->lock);
     450                        return NULL;
     451                }
     452        }
    449453       
    450454        btree_create(&area->used_space);
     
    690694        }
    691695       
     696        if (area->backend && area->backend->resize) {
     697                if (!area->backend->resize(area, pages)) {
     698                        mutex_unlock(&area->lock);
     699                        mutex_unlock(&as->lock);
     700                        return ENOMEM;
     701                }
     702        }
     703       
    692704        area->pages = pages;
    693705       
     
    756768                return ENOENT;
    757769        }
     770
     771        if (area->backend && area->backend->destroy)
     772                area->backend->destroy(area);
    758773       
    759774        uintptr_t base = area->base;
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