Wireshark-dev: [Wireshark-dev] SLAB allocator replaced with EP_ALLOC()
From: "ronnie sahlberg" <[email protected]>
Date: Thu, 21 Dec 2006 09:57:17 +0000
List,

I have successfully converted 3 of the slab allocated structures into
ep-allocated() structures and it works for me.

The structures i converted were the temporary slab storage for
fvalue_t, field_info and item_label_t.

While this might give a minor performance boost IFF we by default
compile the distributable binaries without the debugging support for
emem,   this was not the point of the conversion  but rather what
consequences it would have.

I think, but have not measured, that if we replace the current
allocator with ep memory that we would have a significant performance
regression in mainline distribution of binaries unless we start
compiling our distribution without emem debugging/guardpages etc.


Comments please.
emem debugging/guardpages do not trigger any issues any more so they
have little value left in binary distribution of wireshark. (we do
compile win32 binary with both guardpages and debugging?)


purpose of this change from slab to ep/emem is not performance. i
think if will have neglible performance boost when all debugging/guard
pages are disabled   but rather to remove one small obstacle towards
making it easier in the future to multithread the dissection of
wireshark.
(using ep/emem memory makes it easier in the future if/when we want to
shoot for multithreaded/multicore dissection.  we would need ep_
signatures that allocate from a thread-specific heap though but that
is trivial.)



since this change, which seems to work for me in my tests would have
"sideeffects" in that it would not really be possible anymore if we
want to do debugging/guardpages for the binary w32 distro,   please
comment.


ill check it in tomorrow unless i get "over my dead body" responses.
(with svn it could always be reversed anyway)


((the changes to the code for the patch is primarily removal of code
no longer needed when using ep/emem))