diff options
| author | Darius Davis <darius@vmware.com> | 2021-02-21 20:54:40 +1000 |
|---|---|---|
| committer | Darius Davis <darius@vmware.com> | 2021-02-22 17:00:54 +1000 |
| commit | f895014f6869f201b013c35a0e234cdd0137d170 (patch) | |
| tree | 7c2250e5b16c5992d745adcb02cad842e6cf3340 | |
| parent | 297246093b1639fe989b1060e847df878050bc9e (diff) | |
reassemble: Improve perf of free_all_reassembled_fragments.
When we're walking the list of fragments to free, if we encounter
FD_VISITED_FREE, we can conclude traversal of this fragment list immediately
(and go to the next hash bucket), since everything subsequent to this point in
the list has already been processed by free_all_reassembled_fragments. This
trims an O(n^2) hash table iteration down to O(n).
Before this change, a very ugly 1.1 GByte TFTP capture (with lots of
out-of-order and retransmitted blocks) takes 4 hours to process with
tftp.defragment=TRUE -- output completes after 1.25 hours, and then about
2.75 hours of time is spent doing repeated list traversals within
free_all_reassembled_fragments...(!) With this change, the same test completes
in 1.25 hours, with the cleanup taking just 71 msec.
Tested also with reassemble_test under Valgrind; No issues/leaks were reported.
| -rw-r--r-- | epan/reassemble.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/epan/reassemble.c b/epan/reassemble.c index 09d37c4aba..0994f22954 100644 --- a/epan/reassemble.c +++ b/epan/reassemble.c @@ -376,12 +376,12 @@ free_all_reassembled_fragments(gpointer key_arg _U_, gpointer value, * fragments to array and later free them in * free_fragments() */ - if (fd_head->flags != FD_VISITED_FREE) { - if (fd_head->flags & FD_SUBSET_TVB) - fd_head->tvb_data = NULL; - g_ptr_array_add(allocated_fragments, fd_head); - fd_head->flags = FD_VISITED_FREE; - } + if (fd_head->flags == FD_VISITED_FREE) + break; + if (fd_head->flags & FD_SUBSET_TVB) + fd_head->tvb_data = NULL; + g_ptr_array_add(allocated_fragments, fd_head); + fd_head->flags = FD_VISITED_FREE; } return TRUE; |