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Distribute queries among threads even on platforms without lb sockets

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On platforms without load-balancing socket all the queries would be
handle by a single thread.  Currently, the support for load-balanced
sockets is present in Linux with SO_REUSEPORT and FreeBSD 12 with
SO_REUSEPORT_LB.

This commit adds workaround for such platforms that:

1. setups single shared listening socket for all listening nmthreads for
   UDP, TCP and TCPDNS netmgr transports

2. Calls uv_udp_bind/uv_tcp_bind on the underlying socket just once and
   for rest of the nmthreads only copy the internal libuv flags (should
   be just UV_HANDLE_BOUND and optionally UV_HANDLE_IPV6).

3. start reading on UDP socket or listening on TCP socket

The load distribution among the nmthreads is uneven, but it's still
better than utilizing just one thread for processing all the incoming
queries
This commit is contained in:
Ondřej Surý
2020-12-02 15:37:18 +01:00
parent d0f5407825
commit 1d066e4bc5
6 changed files with 182 additions and 125 deletions
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24
lib/isc/netmgr/netmgr.c
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@@ -169,22 +169,6 @@ isc__nm_in_netthread(void) {
return (isc__nm_tid_v >= 0);
}
static bool
isc__nm_test_lb_socket(sa_family_t sa_family, int protocol) {
isc_result_t result;
uv_os_sock_t fd = -1;
result = isc__nm_socket(sa_family, protocol, 0, &fd);
REQUIRE(result == ISC_R_SUCCESS);
result = isc__nm_socket_reuse_lb(fd);
REQUIRE(result == ISC_R_SUCCESS || result == ISC_R_NOTIMPLEMENTED);
isc__nm_closesocket(fd);
return (result == ISC_R_SUCCESS);
}
#ifdef WIN32
static void
isc__nm_winsock_initialize(void) {
@@ -231,14 +215,6 @@ isc_nm_start(isc_mem_t *mctx, uint32_t workers) {
isc__nm_tls_initialize();
if (!isc__nm_test_lb_socket(AF_INET, SOCK_DGRAM) ||
!isc__nm_test_lb_socket(AF_INET, SOCK_STREAM) ||
!isc__nm_test_lb_socket(AF_INET6, SOCK_DGRAM) ||
!isc__nm_test_lb_socket(AF_INET6, SOCK_STREAM))
{
workers = 1;
}
mgr = isc_mem_get(mctx, sizeof(*mgr));
*mgr = (isc_nm_t){ .nworkers = workers };