From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> 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 <dgilb...@redhat.com> --- exec.c | 17 ++++++++++++++++- trace-events | 3 +++ 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/exec.c b/exec.c index 5973c666c8..7966570231 100644 --- a/exec.c +++ b/exec.c @@ -1665,7 +1665,10 @@ 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; @@ -1682,15 +1685,25 @@ static ram_addr_t find_ram_offset(ram_addr_t size) end = block->offset + block->max_length; + /* Search for the closest following block + * and find the gap. + */ RAMBLOCK_FOREACH(next_block) { if (next_block->offset >= end) { next = MIN(next, next_block->offset); } } + + /* 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 - end >= size && next - end < mingap) { offset = end; mingap = next - end; } + + trace_find_ram_offset_loop(size, offset, end, next, mingap); } if (offset == RAM_ADDR_MAX) { @@ -1699,6 +1712,8 @@ static ram_addr_t find_ram_offset(ram_addr_t size) abort(); } + trace_find_ram_offset(size, offset); + return offset; } diff --git a/trace-events b/trace-events index a8861bd800..23bc036aa1 100644 --- a/trace-events +++ b/trace-events @@ -56,6 +56,9 @@ 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 offset, uint64_t end, uint64_t next, uint64_t mingap) "size: 0x%"PRIx64 " @ 0x%"PRIx64 " end: 0x%"PRIx64" next: 0x%"PRIx64 " mingap: 0x%"PRIx64 + ram_block_discard_range(const char *rbname, void *hva, bool need_madvise, bool need_fallocate, int ret) "%s@%p: madvise: %d fallocate: %d ret: %d" # memory.c -- 2.14.3