From 76335b811b67146bc633e3aa176aad426c30e03a Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 21 Oct 2024 19:12:22 +0300 Subject: [PATCH] build: disable Seastar exception hack In [1], Seastar started to bypass a lock in libgcc's exception throwing mechanism to allow scalability on large machines. The problem is documented in [2] and reported as fixed. In [3], testing results on a 2s96c192t machine are reported. The problem appears indeed fixed with gcc 14's runtime (which we use, even though we build with clang). Given the new results, we can safely drop the exception scalability hack. As [1] states that the hack causes the loss of a translation cache, we may gain some performance this way. With that, we disable the cache by defining some random macro. [1] https://github.com/scylladb/seastar/464f5e3ae43b366b05573018fc46321863bf2fae [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71744 [3] https://github.com/scylladb/seastar/issues/2479#issuecomment-2427098413 --- configure.py | 3 +++ 1 file changed, 3 insertions(+) diff --git a/configure.py b/configure.py index 0a4393261af6..5d0f8e672400 100755 --- a/configure.py +++ b/configure.py @@ -1662,6 +1662,9 @@ def dynamic_linker_option(): curdir = os.getcwd() user_cflags = args.user_cflags + f" -ffile-prefix-map={curdir}=." +# Since gcc 13, libgcc doesn't need the exception workaround +user_cflags += ' -DSEASTAR_NO_EXCEPTION_HACK' + if args.target != '': user_cflags += ' -march=' + args.target