On 16.04.20 18:43, Dario Faggioli wrote:
On Thu, 2020-04-16 at 09:33 +0100, Sergey Dyasli wrote:
Currently it might be not obvious which scheduling mode is being used
by the scheduler. Alleviate this by printing additional information
about the selected granularity.
I like the idea. However, I don't like how verbose and long that line
becomes.
Messages now look like these:
1. boot
(XEN) [00089808f0ea7496] Using scheduler: SMP Credit Scheduler
(credit) in core-scheduling mode
2. xl debug-keys r
(XEN) [ 45.914314] Scheduler: SMP Credit Scheduler (credit) in 2-
way core-scheduling mode
What about adding an entry, just below these ones. Something looking
like, for instance (both at boot and in the debug-key dump):
"Scheduling granularity: cpu"
(or "core", or "socket")
Also
--- a/xen/common/sched/cpupool.c
+++ b/xen/common/sched/cpupool.c
@@ -38,7 +38,35 @@ static cpumask_t cpupool_locked_cpus;
static DEFINE_SPINLOCK(cpupool_lock);
static enum sched_gran __read_mostly opt_sched_granularity =
SCHED_GRAN_cpu;
-static unsigned int __read_mostly sched_granularity = 1;
+static unsigned int __read_mostly sched_granularity;
+
+char *sched_gran_str(char *str, size_t size)
+{
+ char *mode = "";
+
+ switch ( opt_sched_granularity )
+ {
+ case SCHED_GRAN_cpu:
+ mode = "cpu";
+ break;
+ case SCHED_GRAN_core:
+ mode = "core";
+ break;
+ case SCHED_GRAN_socket:
+ mode = "socket";
+ break;
+ default:
+ ASSERT_UNREACHABLE();
+ break;
+ }
+
+ if ( sched_granularity )
+ snprintf(str, size, "%u-way %s", sched_granularity, mode);
I'm not sure about using the value of the enum like this.
enum? sched_granularity holds the number of cpus per scheduling
resource. opt_sched_granularity is the enum.
E.g., in a system with 4 threads per core, enabling core scheduling
granularity would mean having 4 vCPUs in the scheduling units. But this
will still print "2-way core-scheduling", which I think would sound
confusing.
It would print "4-way", of course.
So I'd just go with "cpu", "core" and "socket" strings.
No, this is not a good idea. With e.g. smt=0 you'll be able to have
"1-way core" which is much more informative than "core".
Juergen
