On 30.09.19 12:39, Jan Beulich wrote:
On 30.09.2019 12:38, Andrew Cooper wrote:
On 30/09/2019 11:36, Jan Beulich wrote:
On 30.09.2019 07:21, Juergen Gross wrote:
When switching sched units synchronize all vcpus of the new unit to be
scheduled at the same time.
A variable sched_granularity is added which holds the number of vcpus
per schedule unit.
As tasklets require to schedule the idle unit it is required to set the
tasklet_work_scheduled parameter of do_schedule() to true if any cpu
covered by the current schedule() call has any pending tasklet work.
For joining other vcpus of the schedule unit we need to add a new
softirq SCHED_SLAVE_SOFTIRQ in order to have a way to initiate a
context switch without calling the generic schedule() function
selecting the vcpu to switch to, as we already know which vcpu we
want to run. This has the other advantage not to loose any other
concurrent SCHEDULE_SOFTIRQ events.
Signed-off-by: Juergen Gross <[email protected]>
Reviewed-by: Dario Faggioli <[email protected]>
x86 and applicable common code parts
Acked-by: Jan Beulich <[email protected]>
However, ...
+static void sched_context_switch(struct vcpu *vprev, struct vcpu *vnext,
+ s_time_t now)
+{
+ if ( unlikely(vprev == vnext) )
{
- pcpu_schedule_unlock_irq(lock, cpu);
TRACE_4D(TRC_SCHED_SWITCH_INFCONT,
- next->domain->domain_id, next->unit_id,
- now - prev->state_entry_time,
- prev->next_time);
- trace_continue_running(next->vcpu_list);
- return continue_running(prev->vcpu_list);
+ vnext->domain->domain_id, vnext->sched_unit->unit_id,
+ now - vprev->runstate.state_entry_time,
+ vprev->sched_unit->next_time);
+ sched_context_switched(vprev, vnext);
+ trace_continue_running(vnext);
+ return continue_running(vprev);
}
... I don't recall if there weren't compiler (clang?) versions not
allowing (or at least warning about) use of this extension.
Which extension?
"return" with an expression of "void" type.
It was there in the original code, too:
http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/common/schedule.c;h=fd587622f4c3ee13d57334f90b1eab4b17031c0b;hb=refs/heads/staging-4.12#l1536
Juergen
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