Author: hiren
Date: Wed May 13 08:04:50 2015
New Revision: 282832
URL: https://svnweb.freebsd.org/changeset/base/282832
Log:
MFC r281984:
Currently there is no easy way to specify net.isr.maxthreads = all cpus. We
need
to specify exact number of cpus in loader.conf which get annoying when you
have
mix of machines which don't have equal number of total cpus. I propose "-1" as
that value. When loader.conf has net.isr.maxthreads = -1, netisr will use all
available cpus.
Sponsored by: Limelight Networks
Modified:
stable/10/sys/net/netisr.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/net/netisr.c
==============================================================================
--- stable/10/sys/net/netisr.c Wed May 13 07:39:16 2015 (r282831)
+++ stable/10/sys/net/netisr.c Wed May 13 08:04:50 2015 (r282832)
@@ -156,10 +156,13 @@ SYSCTL_PROC(_net_isr, OID_AUTO, dispatch
/*
* Allow the administrator to limit the number of threads (CPUs) to use for
* netisr. We don't check netisr_maxthreads before creating the thread for
- * CPU 0, so in practice we ignore values <= 1. This must be set at boot.
- * We will create at most one thread per CPU.
+ * CPU 0. This must be set at boot. We will create at most one thread per CPU.
+ * By default we initialize this to 1 which would assign just 1 cpu (cpu0) and
+ * therefore only 1 workstream. If set to -1, netisr would use all cpus
+ * (mp_ncpus) and therefore would have those many workstreams. One workstream
+ * per thread (CPU).
*/
-static int netisr_maxthreads = -1; /* Max number of threads. */
+static int netisr_maxthreads = 1; /* Max number of threads. */
TUNABLE_INT("net.isr.maxthreads", &netisr_maxthreads);
SYSCTL_INT(_net_isr, OID_AUTO, maxthreads, CTLFLAG_RDTUN,
&netisr_maxthreads, 0,
@@ -1128,8 +1131,10 @@ netisr_init(void *arg)
KASSERT(curcpu == 0, ("%s: not on CPU 0", __func__));
NETISR_LOCK_INIT();
- if (netisr_maxthreads < 1)
- netisr_maxthreads = 1;
+ if (netisr_maxthreads == 0 || netisr_maxthreads < -1 )
+ netisr_maxthreads = 1; /* default behavior */
+ else if (netisr_maxthreads == -1)
+ netisr_maxthreads = mp_ncpus; /* use max cpus */
if (netisr_maxthreads > mp_ncpus) {
printf("netisr_init: forcing maxthreads from %d to %d\n",
netisr_maxthreads, mp_ncpus);
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