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[Qemu-devel] [PATCH 1/2] find_ram_offset: Add comments and tracing
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PATCH 1/2] find_ram_offset: Add comments and tracing |
Date: |
Fri, 5 Jan 2018 17:01:37 +0000 |
From: "Dr. David Alan Gilbert" <address@hidden>
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 <address@hidden>
---
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) "address@hidden: madvise: %d fallocate: %d ret: %d"
# memory.c
--
2.14.3