Commit 154cc9ea authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Paolo Bonzini
Browse files

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: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20180105170138.23357-2-dgilbert@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent aa777e29

exec.c

+22 −7
Original line number Diff line number Diff line
@@ -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;

}

trace-events

+4 −0
Original line number Diff line number Diff line
@@ -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"