From: Witold Kręcicki <wpk@isc.org>
Date: Wed, 29 Jan 2020 08:29:19 +0000 (+0100)
Subject: Use the original threadid when sending a UDP packet to decrease probability of contex... 
X-Git-Tag: v9.17.1~90^2~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb874608c1929df6b2fa81ec31b64b3901e85c16;p=thirdparty%2Fbind9.git

Use the original threadid when sending a UDP packet to decrease probability of context switching
---

diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index 6e229e1eea6..84ac0d65278 100644
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -383,8 +383,16 @@ isc__nm_udp_send(isc_nmhandle_t *handle, isc_region_t *region, isc_nm_cb_t cb,
 		return (ISC_R_CANCELED);
 	}
 
+	/*
+	 * If we're in netthread - send it directly
+	 * If the original packet was received over a regular socket
+	 * - send it over the same thread (assuming cpu affinity)
+	 * Otherwise - use a random thread.
+	 */
 	if (isc__nm_in_netthread()) {
 		ntid = isc_nm_tid();
+	} else if (sock->type == isc_nm_udpsocket) {
+		ntid = sock->tid;
 	} else {
 		ntid = (int)isc_random_uniform(sock->nchildren);
 	}