From: Juergen Gross <jgross@suse.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Tim Deegan <tim@xen.org>, Dario Faggioli <dfaggioli@suse.com>,
Julien Grall <julien.grall@arm.com>,
xen-devel@lists.xenproject.org,
Ian Jackson <ian.jackson@eu.citrix.com>
Subject: Re: [Xen-devel] [PATCH v2 31/48] xen/sched: add support for multiple vcpus per sched unit where missing
Date: Fri, 13 Sep 2019 17:01:56 +0200 [thread overview]
Message-ID: <e4d759d5-75a7-4428-8b12-7532275cf595@suse.com> (raw)
In-Reply-To: <f76aba47-e3c7-b8c6-03ac-b6862106d01c@suse.com>
On 11.09.19 12:43, Jan Beulich wrote:
> On 09.08.2019 16:58, Juergen Gross wrote:
>> V1:
>> - add special handling for idle unit in unit_runnable() and
>> unit_runnable_state()
>
> Why was this done? Isn't vcpu_runnable() going to always return
> true for idle vCPU-s?
The problem is the for_each_sched_unit_vcpu() loop handling.
The loop is ending as soon as vcpu->sched_unit != unit. But this
might be true for idle vcpus in case they are temporarily active
for a normal domain's unit.
>
>> --- a/xen/common/domain.c
>> +++ b/xen/common/domain.c
>> @@ -1255,7 +1255,10 @@ int vcpu_reset(struct vcpu *v)
>> v->async_exception_mask = 0;
>> memset(v->async_exception_state, 0, sizeof(v->async_exception_state));
>> #endif
>> - v->affinity_broken = 0;
>> + if ( v->affinity_broken & VCPU_AFFINITY_OVERRIDE )
>> + vcpu_temporary_affinity(v, NR_CPUS, VCPU_AFFINITY_OVERRIDE);
>> + if ( v->affinity_broken & VCPU_AFFINITY_WAIT )
>> + vcpu_temporary_affinity(v, NR_CPUS, VCPU_AFFINITY_WAIT);
>
> Shouldn't this live in an earlier patch? I guess the same question
> is applicable to almost everything here, as also already mentioned
> e.g. in the previous patch.
Hmm, this _is_ a missing part for multiple vcpus per unit.
I wouldn't know which other patch would be more suitable.
>
>> static inline void sched_set_res(struct sched_unit *unit,
>> struct sched_resource *res)
>> {
>> - unit->vcpu_list->processor = res->processor;
>> + int cpu = cpumask_first(res->cpus);
>
> unsigned int
Yes.
>
>> static inline void sched_set_pause_flags_atomic(struct sched_unit *unit,
>> unsigned int bit)
>> {
>> - set_bit(bit, &unit->vcpu_list->pause_flags);
>> + struct vcpu *v;
>> +
>> + for_each_sched_unit_vcpu ( unit, v )
>> + set_bit(bit, &v->pause_flags);
>> }
>>
>> static inline void sched_clear_pause_flags_atomic(struct sched_unit *unit,
>> unsigned int bit)
>> {
>> - clear_bit(bit, &unit->vcpu_list->pause_flags);
>> + struct vcpu *v;
>> +
>> + for_each_sched_unit_vcpu ( unit, v )
>> + clear_bit(bit, &v->pause_flags);
>> }
>
> The atomicity is (necessarily) limited here - it's atomic for an
> individual vCPU, but not atomic for a unit as a whole. If this
> is indeed a useful hybrid, then I think it would be nice if there
> was a comment next to these functions clarifying under what
> conditions use of them is correct without it also being correct
> to use their non-atomic counterparts (e.g. due to use of an
> external lock).
Okay, I'll add that.
Juergen
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next prev parent reply other threads:[~2019-09-13 15:02 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 14:57 [Xen-devel] [PATCH v2 00/48] xen: add core scheduling support Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 01/48] xen/sched: use new sched_unit instead of vcpu in scheduler interfaces Juergen Gross
2019-09-02 9:07 ` Jan Beulich
2019-09-09 5:26 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 02/48] xen/sched: move per-vcpu scheduler private data pointer to sched_unit Juergen Gross
2019-08-23 10:47 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 03/48] xen/sched: build a linked list of struct sched_unit Juergen Gross
2019-08-23 10:52 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 04/48] xen/sched: introduce struct sched_resource Juergen Gross
2019-08-23 10:54 ` Dario Faggioli
2019-09-04 13:10 ` Jan Beulich
2019-09-09 5:31 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 05/48] xen/sched: let pick_cpu return a scheduler resource Juergen Gross
2019-09-04 13:34 ` Jan Beulich
2019-09-09 5:43 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 06/48] xen/sched: switch schedule_data.curr to point at sched_unit Juergen Gross
2019-09-04 13:36 ` Jan Beulich
2019-09-09 5:46 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 07/48] xen/sched: move per cpu scheduler private data into struct sched_resource Juergen Gross
2019-09-04 13:48 ` Jan Beulich
2019-09-05 7:13 ` Juergen Gross
2019-09-05 7:38 ` Jan Beulich
2019-09-09 13:03 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 08/48] xen/sched: switch vcpu_schedule_lock to unit_schedule_lock Juergen Gross
2019-09-04 14:02 ` Jan Beulich
2019-09-04 14:41 ` Juergen Gross
2019-09-04 14:54 ` Jan Beulich
2019-09-04 15:02 ` Juergen Gross
2019-09-11 16:02 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 09/48] xen/sched: move some per-vcpu items to struct sched_unit Juergen Gross
2019-09-04 14:16 ` Jan Beulich
2019-09-09 6:39 ` Juergen Gross
2019-09-09 6:55 ` Jan Beulich
2019-09-09 7:05 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 10/48] xen/sched: add scheduler helpers hiding vcpu Juergen Gross
2019-09-04 14:49 ` Jan Beulich
2019-09-11 13:22 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 11/48] xen/sched: rename scheduler related perf counters Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 12/48] xen/sched: switch struct task_slice from vcpu to sched_unit Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 13/48] xen/sched: add is_running indicator to struct sched_unit Juergen Gross
2019-09-04 15:06 ` Jan Beulich
2019-09-11 13:44 ` Juergen Gross
2019-09-11 15:06 ` Jan Beulich
2019-09-11 15:32 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 14/48] xen/sched: make null scheduler vcpu agnostic Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 15/48] xen/sched: make rt " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 16/48] xen/sched: make credit " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 17/48] xen/sched: make credit2 " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 18/48] xen/sched: make arinc653 " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 19/48] xen: add sched_unit_pause_nosync() and sched_unit_unpause() Juergen Gross
2019-09-09 13:34 ` Jan Beulich
2019-09-11 14:15 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 20/48] xen: let vcpu_create() select processor Juergen Gross
2019-08-23 16:42 ` Julien Grall
2019-09-09 13:38 ` Jan Beulich
2019-09-11 14:22 ` Juergen Gross
2019-09-11 17:20 ` Dario Faggioli
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 21/48] xen/sched: use sched_resource cpu instead smp_processor_id in schedulers Juergen Gross
2019-09-09 14:17 ` Jan Beulich
2019-09-12 9:34 ` Juergen Gross
2019-09-12 10:04 ` Jan Beulich
2019-09-12 11:03 ` Juergen Gross
2019-09-12 11:17 ` Juergen Gross
2019-09-12 11:46 ` Jan Beulich
2019-09-12 11:53 ` Juergen Gross
2019-09-12 12:08 ` Jan Beulich
2019-09-12 12:13 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 22/48] xen/sched: switch schedule() from vcpus to sched_units Juergen Gross
2019-09-09 14:35 ` Jan Beulich
2019-09-12 13:44 ` Juergen Gross
2019-09-12 14:34 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 23/48] xen/sched: switch sched_move_irqs() to take sched_unit as parameter Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 24/48] xen: switch from for_each_vcpu() to for_each_sched_unit() Juergen Gross
2019-09-09 15:14 ` Jan Beulich
2019-09-12 14:02 ` Juergen Gross
2019-09-12 14:40 ` Jan Beulich
2019-09-12 14:47 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 25/48] xen/sched: add runstate counters to struct sched_unit Juergen Gross
2019-09-09 14:30 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 26/48] xen/sched: rework and rename vcpu_force_reschedule() Juergen Gross
2019-09-10 14:06 ` Jan Beulich
2019-09-13 9:33 ` Juergen Gross
2019-09-13 9:40 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 27/48] xen/sched: Change vcpu_migrate_*() to operate on schedule unit Juergen Gross
2019-09-10 15:11 ` Jan Beulich
2019-09-13 12:33 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 28/48] xen/sched: move struct task_slice into struct sched_unit Juergen Gross
2019-09-10 15:18 ` Jan Beulich
2019-09-13 12:56 ` Juergen Gross
2019-09-12 8:13 ` Dario Faggioli
2019-09-12 8:21 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 29/48] xen/sched: add code to sync scheduling of all vcpus of a sched unit Juergen Gross
2019-09-10 15:36 ` Jan Beulich
2019-09-13 13:12 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 30/48] xen/sched: introduce unit_runnable_state() Juergen Gross
2019-09-11 10:30 ` Jan Beulich
2019-09-12 10:22 ` Dario Faggioli
2019-09-13 14:07 ` Juergen Gross
2019-09-13 14:44 ` Jan Beulich
2019-09-13 15:23 ` Juergen Gross
2019-09-12 10:24 ` Dario Faggioli
2019-09-13 14:14 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 31/48] xen/sched: add support for multiple vcpus per sched unit where missing Juergen Gross
2019-09-11 10:43 ` Jan Beulich
2019-09-13 15:01 ` Juergen Gross [this message]
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 32/48] xen/sched: modify cpupool_domain_cpumask() to be an unit mask Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 33/48] xen/sched: support allocating multiple vcpus into one sched unit Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 34/48] xen/sched: add a percpu resource index Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 35/48] xen/sched: add fall back to idle vcpu when scheduling unit Juergen Gross
2019-09-11 11:33 ` Julien Grall
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 36/48] xen/sched: make vcpu_wake() and vcpu_sleep() core scheduling aware Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 37/48] xen/sched: carve out freeing sched_unit memory into dedicated function Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 38/48] xen/sched: move per-cpu variable scheduler to struct sched_resource Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 39/48] xen/sched: move per-cpu variable cpupool " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 40/48] xen/sched: reject switching smt on/off with core scheduling active Juergen Gross
2019-09-10 15:47 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 41/48] xen/sched: prepare per-cpupool scheduling granularity Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 42/48] xen/sched: split schedule_cpu_switch() Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 43/48] xen/sched: protect scheduling resource via rcu Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 44/48] xen/sched: support multiple cpus per scheduling resource Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 45/48] xen/sched: support differing granularity in schedule_cpu_[add/rm]() Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 46/48] xen/sched: support core scheduling for moving cpus to/from cpupools Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 47/48] xen/sched: disable scheduling when entering ACPI deep sleep states Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 48/48] xen/sched: add scheduling granularity enum Juergen Gross
2019-08-15 10:17 ` [Xen-devel] [PATCH v2 00/48] xen: add core scheduling support Sergey Dyasli
2019-09-05 6:22 ` Juergen Gross
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