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https://git.code.sf.net/p/quake/quakeforge
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0ebb0717b0
The tests fail as they exercise how the cache *SHOULD* work rather than
how it does now.
The tests do currently pass for the pending work I've done on the cache
system, but while working on it, I remembered why I reworked cache
allocation...
The essential problem is that sounds are loaded into the cache, which is
fine for synchronous output targets, but has proven to be a minefield
for asynchronous output targets (JACK, ALSA).
The reason for the minefield is the hunk takes priority over the cache,
and is free to move cache blocks around, and *even dispose of them
entirely* in order to satisfy memory allocations from either end of the
hunk. Doing this in an entirely single-threaded process (as DOS Quake
was) is perfectly safe, as the users of the cache just reload the
pointer each time, and bail if it's null (meaning the block has been
freed), or even cause the data to be reloaded if possible (I'm a little
fuzzy on the details for that as I didn't write that code). However, in
multi-threaded code, especially real-time (JACK, possibly ALSA), it's a
recipe for disaster. The 4cab5b90e6
commit was a (mostly) successful
attempt to mitigate the problem by allocating the cache blocks from the
high-hunk (thus minimizing any movement caused by low-hunk allocations),
it resulted in cache allocates and regular high-hunk allocations somehow
getting intertwined: while investigating just how much memory ad_tears
needs (somewhere between 192MB and 256MB), I got "trashed sentinel"
errors and upon investigation, I found what looks very suspiciously like
audio data written across a hunk control block.
I've decided that the cache allocation *algorithm* should be reverted to
how it was originally designed by Id (details will remain "modern"), but
while working on the tests, I remembered why I had done the changes in
the first place (above story). Thus the work on reverting the cache
allocation can't go in until I get sound memory management independent
of the cache. The tests are going in now so I have a constant reminder :)
217 lines
6 KiB
C
217 lines
6 KiB
C
#define PARANOID
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#include "../zone.c"
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static int
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check_hunk_block (const memhunk_t *hunk, const void *mem, size_t size)
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{
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const hunkblk_t *h = (const hunkblk_t *) mem - 1;
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if (h->sentinal1 != HUNK_SENTINAL || h->sentinal2 != HUNK_SENTINAL) {
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printf ("invalid sentinals: %u %u\n", h->sentinal1, h->sentinal2);
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return 1;
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}
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if (h->size % HUNK_ALIGN) {
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printf ("block size misaligned: %zd %zd\n",
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h->size, h->size % HUNK_ALIGN);
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return 1;
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}
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if (h->size - sizeof (hunkblk_t) < size) {
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printf ("block size too small: %zd %zd\n",
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h->size - sizeof (hunkblk_t), size);
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return 1;
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}
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if (h->size - sizeof (hunkblk_t) - size >= HUNK_ALIGN) {
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printf ("block size too small: %zd %d\n",
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h->size - sizeof (hunkblk_t) - size, HUNK_ALIGN);
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return 1;
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}
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if ((byte *) h < hunk->base
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|| (byte *) h + h->size > hunk->base + hunk->size) {
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printf ("block outside of hunk: %p %p, %p %p\n",
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h, hunk->base, (byte *) h + h->size, hunk->base + hunk->size);
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return 1;
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}
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size_t offset = (byte *) h - hunk->base;
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if (offset < hunk->size - hunk->high_used
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&& offset + h->size > hunk->low_used) {
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printf ("block in unallocated region: %zd %zd, %zd %zd\n",
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offset, offset + h->size,
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hunk->low_used, hunk->size - hunk->high_used);
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return 1;
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}
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return 0;
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}
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static int
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check_cache_block (const memhunk_t *hunk, const void *c, size_t size)
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{
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if (!c) {
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printf ("cache block is null\n");
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return 1;
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}
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const cache_system_t *cs = (cache_system_t *) c - 1;
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size_t hunk_high = hunk->size - hunk->high_used;
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size_t offset = (byte *) cs - hunk->base;
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if (offset < hunk->low_used || offset + cs->size > hunk_high) {
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printf ("cache block in hunk stack: %zd %zd, %zd, %zd\n",
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offset, offset + cs->size, hunk->low_used, hunk_high);
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return 1;
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}
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return 0;
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}
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static int
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check_cache_order (memhunk_t *hunk)
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{
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uint32_t ci;
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cache_system_t *c;
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int ret = 0;
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cache_system_t *first = cs_ptr (hunk, hunk->cache_head[0].next);
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cache_system_t *last = cs_ptr (hunk, hunk->cache_head[0].prev);
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if (first->prev) {
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printf ("first cache block does not point back to head: %u\n",
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first->prev);
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}
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if (last->next) {
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printf ("last cache block does not point forward to head: %u\n",
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last->next);
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}
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if (first->prev || last->next) {
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exit (1); // unsafe to continue
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}
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uint32_t prev = 0;
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for (ci = hunk->cache_head[0].next; ci; prev = ci, ci = c->next) {
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c = cs_ptr (hunk, ci);
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if ((byte *) c + c->size > hunk->base + hunk->size) {
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printf ("cache block outside of hunk (from %u)\n", prev);
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exit (1);
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}
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if (c->readlock) {
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printf ("look in cache detected at %u\n", ci);
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exit (1);
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}
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c->readlock = 1;
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if (c->next && c->next < ci) {
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printf ("cache block sequence incorrect %u -> %u\n", prev, ci);
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ret |= 1;
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}
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}
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return ret;
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}
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int
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main (int argc, const char **argv)
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{
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int ret = 0;
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if (sizeof (memhunk_t) != 128) {
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ret = 1;
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printf ("memhunk_t not 128 bytes: %zd\n", sizeof (memhunk_t));
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}
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if (sizeof (hunkblk_t) != 64) {
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ret = 1;
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printf ("hunkblk_t not 64 bytes: %zd\n", sizeof (memhunk_t));
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}
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size_t memsize = 64 * 1024;
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void *hunk_mem = Sys_Alloc (memsize);
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if ((intptr_t) hunk_mem & 63) {
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// (not really part of test, but relied upon) should be 4k
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// aligned, but doesn't matter for the tests
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printf ("Sys_Alloc returned unaligned memory");
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ret = 1;
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}
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memhunk_t *hunk = Hunk_Init (hunk_mem, memsize);
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if ((void *) hunk != hunk_mem) {
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ret = 1;
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printf ("hunk moved\n");
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}
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if ((void *) hunk->base != (void *)&hunk[1]) {
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ret = 1;
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printf ("hunk->base does not point to beginning of hunk space\n");
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}
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if (hunk->size != memsize - sizeof (memhunk_t)) {
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ret = 1;
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printf ("hunk size not memsize - sizeof (memhunk_t) (%zd - %zd): %zd\n",
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memsize, sizeof (memhunk_t), hunk->size);
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}
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if (hunk->low_used || hunk->high_used) {
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ret = 1;
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printf ("hunk low and high used not 0: %zd %zd\n",
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hunk->low_used, hunk->high_used);
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}
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if (hunk->tempmark || hunk->tempactive) {
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ret = 1;
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printf ("hunk tempmark tempactive not 0: %zd %d\n",
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hunk->tempmark, hunk->tempactive);
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}
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if (ret) {
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// no point continuing
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return 1;
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}
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size_t low_mark = Hunk_LowMark (hunk);
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if (low_mark != 0) {
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ret = 1;
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printf ("initial hunk low mark not 0: %zd\n", low_mark);
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}
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size_t size = 1024;
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void *low = Hunk_AllocName (hunk, size, "low test");
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ret |= check_hunk_block (hunk, low, size);
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if (low > (void *) (hunk->base + sizeof (hunkblk_t))) {
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ret = 1;
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printf ("low memory not at beginning of hunk: %p %p\n",
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low, hunk->base + sizeof (hunkblk_t));
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}
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size_t high_mark = Hunk_HighMark (hunk);
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if (high_mark != 0) {
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ret = 1;
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printf ("initial hunk high mark not 0: %zd\n", high_mark);
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}
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void *high = Hunk_HighAlloc (hunk, size);//FIXME, "high test");
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ret |= check_hunk_block (hunk, high, size);
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if (high + size < (void *) (hunk->base + hunk->size)) {
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ret = 1;
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printf ("high memory not at end of hunk: %p %p\n",
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high + size, hunk->base + hunk->size);
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}
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global_hunk = hunk;//FIXME put hunk in cache_user_t ?
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cache_user_t cu = {};
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void *cm = Cache_Alloc (&cu, 512, "cache test");
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ret |= check_cache_block (hunk, cm, 512);
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size_t mark = Hunk_LowMark (hunk);
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void *low2 = Hunk_AllocName (hunk, 61 * 1024, "low test 2");
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ret |= check_hunk_block (hunk, low2, 61 * 1024);
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if (cm == Cache_Check (&cu)) {
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ret = 1;
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printf ("cache block was not moved\n");
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}
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cm = Cache_Check (&cu);
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ret |= check_cache_block (hunk, cm, 512);
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Hunk_FreeToLowMark (hunk, mark);
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if (cm != Cache_Check (&cu)) {
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ret = 1;
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printf ("cache block was moved\n");
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}
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void *high2 = Hunk_HighAlloc (hunk, 2 * 1024);
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ret |= check_hunk_block (hunk, high2, 2 * 1024);
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if (cm == Cache_Check (&cu)) {
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ret = 1;
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printf ("cache block was not moved\n");
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}
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cm = Cache_Check (&cu);
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ret |= check_cache_block (hunk, cm, 512);
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printf ("%zd %zd %zd\n", hunk->low_used, hunk->size - hunk->high_used,
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(byte *) cm - hunk->base);
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check_cache_order (hunk);
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Hunk_Print(hunk, 1);
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Cache_Print ();
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return ret;
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}
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