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find_ram_offset: Add comments and tracing 

Add some comments so I can understand the various nested loops.
Add some tracing so I can see what they're doing.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20180105170138.23357-2-dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2018-01-05 17:01:37 +00:00 committed by Paolo Bonzini
parent aa777e297c
commit 154cc9ea3b
2 changed files with 26 additions and 7 deletions
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29
exec.c
View File

@ -1660,7 +1660,10 @@ static void *file_ram_alloc(RAMBlock *block,
}
#endif
/* Called with the ramlist lock held. */
/* Allocate space within the ram_addr_t space that governs the
* dirty bitmaps.
* Called with the ramlist lock held.
*/
static ram_addr_t find_ram_offset(ram_addr_t size)
{
RAMBlock *block, *next_block;
@ -1673,19 +1676,29 @@ static ram_addr_t find_ram_offset(ram_addr_t size)
}
RAMBLOCK_FOREACH(block) {
ram_addr_t end, next = RAM_ADDR_MAX;
ram_addr_t candidate, next = RAM_ADDR_MAX;
end = block->offset + block->max_length;
candidate = block->offset + block->max_length;
/* Search for the closest following block
* and find the gap.
*/
RAMBLOCK_FOREACH(next_block) {
if (next_block->offset >= end) {
if (next_block->offset >= candidate) {
next = MIN(next, next_block->offset);
}
}
if (next - end >= size && next - end < mingap) {
offset = end;
mingap = next - end;
/* If it fits remember our place and remember the size
* of gap, but keep going so that we might find a smaller
* gap to fill so avoiding fragmentation.
*/
if (next - candidate >= size && next - candidate < mingap) {
offset = candidate;
mingap = next - candidate;
}
trace_find_ram_offset_loop(size, candidate, offset, next, mingap);
}
if (offset == RAM_ADDR_MAX) {
@ -1694,6 +1707,8 @@ static ram_addr_t find_ram_offset(ram_addr_t size)
abort();
}
trace_find_ram_offset(size, offset);
return offset;
}

4
trace-events
View File

@ -55,6 +55,10 @@ dma_complete(void *dbs, int ret, void *cb) "dbs=%p ret=%d cb=%p"
dma_blk_cb(void *dbs, int ret) "dbs=%p ret=%d"
dma_map_wait(void *dbs) "dbs=%p"
# # exec.c
find_ram_offset(uint64_t size, uint64_t offset) "size: 0x%" PRIx64 " @ 0x%" PRIx64
find_ram_offset_loop(uint64_t size, uint64_t candidate, uint64_t offset, uint64_t next, uint64_t mingap) "trying size: 0x%" PRIx64 " @ 0x%" PRIx64 ", offset: 0x%" PRIx64" next: 0x%" PRIx64 " mingap: 0x%" PRIx64
# memory.c
memory_region_ops_read(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"
memory_region_ops_write(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"