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Currently there is no easy way to specify net.isr.maxthreads = all cpus. We need

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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.

In collaboration with:	davide
Reviewed by:	gnn
Differential Revision:	https://reviews.freebsd.org/D2318
MFC after:	2 weeks
Sponsored by:	Limelight Networks
This commit is contained in:
hiren 2015-04-25 16:12:06 +00:00
parent ed8c3c1f90
commit c60c12803e
1 changed files with 10 additions and 5 deletions
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15
sys/net/netisr.c
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@ -156,10 +156,13 @@ SYSCTL_PROC(_net_isr, OID_AUTO, dispatch, CTLTYPE_STRING | CTLFLAG_RWTUN,
/*
* 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. */
SYSCTL_INT(_net_isr, OID_AUTO, maxthreads, CTLFLAG_RDTUN,
&netisr_maxthreads, 0,
"Use at most this many CPUs for netisr processing");
@ -1120,8 +1123,10 @@ 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);