| Message ID | 20191108065739.21345-1-jgross@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen/sched: fix a potential issue with core scheduling | expand |
On Fri, 2019-11-08 at 07:57 +0100, Juergen Gross wrote: > cpupool_online_cpumask() is used by credit and rt scheduler. It > returns > all the cpus of a cpupool or all online cpus in case no cpupool is > specified. > > The "no cpupool" case can be dropped, as no scheduler other than the > init scheduler will ever work on cpus not associated with any > cpupool. > Yes, this is a cool thing about having the init cpupool/idle scheduler in place. It's even cooler in Credit2, where it will allow us to drop some of the cpumask_and() cpumask_or() operations. It's the reason why, even before core scheduling, I was considering doing an idle scheduler myself. I'll get to write that patch (the one for Credit2, I mean) at some point. :-) > As the individual schedulers should only ever work on scheduling > resources instead of individual cpus, their cpupool_online_cpumask() > use should be replaced by cpupool->res_valid. > > Note that only with core scheduling active this might result in > potential problems, as with cpu scheduling both masks are identical. > > Signed-off-by: Juergen Gross <jgross@suse.com> > Reviewed-by: Dario Faggioli <dfaggioli@suse.com> Regards
On 12.11.19 10:14, Dario Faggioli wrote: > On Fri, 2019-11-08 at 07:57 +0100, Juergen Gross wrote: >> cpupool_online_cpumask() is used by credit and rt scheduler. It >> returns >> all the cpus of a cpupool or all online cpus in case no cpupool is >> specified. >> >> The "no cpupool" case can be dropped, as no scheduler other than the >> init scheduler will ever work on cpus not associated with any >> cpupool. >> > Yes, this is a cool thing about having the init cpupool/idle scheduler > in place. It's even cooler in Credit2, where it will allow us to drop > some of the cpumask_and() cpumask_or() operations. > > It's the reason why, even before core scheduling, I was considering > doing an idle scheduler myself. > > I'll get to write that patch (the one for Credit2, I mean) at some > point. :-) > >> As the individual schedulers should only ever work on scheduling >> resources instead of individual cpus, their cpupool_online_cpumask() >> use should be replaced by cpupool->res_valid. >> >> Note that only with core scheduling active this might result in >> potential problems, as with cpu scheduling both masks are identical. >> >> Signed-off-by: Juergen Gross <jgross@suse.com> >> > Reviewed-by: Dario Faggioli <dfaggioli@suse.com> And with my release manager hat on: Release-acked-by: Juergen Gross <jgross@suse.com> Juergen
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c index fbffcf3996..645cdc5e9a 100644 --- a/xen/common/sched_credit.c +++ b/xen/common/sched_credit.c @@ -1684,12 +1684,11 @@ csched_load_balance(struct csched_private *prv, int cpu, struct cpupool *c = get_sched_res(cpu)->cpupool; struct csched_unit *speer; cpumask_t workers; - cpumask_t *online; + cpumask_t *online = c->res_valid; int peer_cpu, first_cpu, peer_node, bstep; int node = cpu_to_node(cpu); BUG_ON(get_sched_res(cpu) != snext->unit->res); - online = cpupool_online_cpumask(c); /* * If this CPU is going offline, or is not (yet) part of any cpupool diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c index 6e93e50acb..b2b29481f3 100644 --- a/xen/common/sched_rt.c +++ b/xen/common/sched_rt.c @@ -774,8 +774,8 @@ rt_deinit_pdata(const struct scheduler *ops, void *pcpu, int cpu) if ( prv->repl_timer.cpu == cpu ) { - struct cpupool *c = get_sched_res(cpu)->cpupool; - unsigned int new_cpu = cpumask_cycle(cpu, cpupool_online_cpumask(c)); + cpumask_t *online = get_sched_res(cpu)->cpupool->res_valid; + unsigned int new_cpu = cpumask_cycle(cpu, online); /* * Make sure the timer run on one of the cpus that are still available diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h index 29715652bc..b0ac54e63d 100644 --- a/xen/include/xen/sched-if.h +++ b/xen/include/xen/sched-if.h @@ -545,9 +545,6 @@ struct cpupool enum sched_gran gran; }; -#define cpupool_online_cpumask(_pool) \ - (((_pool) == NULL) ? &cpu_online_map : (_pool)->cpu_valid) - static inline cpumask_t *cpupool_domain_master_cpumask(const struct domain *d) { /*
cpupool_online_cpumask() is used by credit and rt scheduler. It returns all the cpus of a cpupool or all online cpus in case no cpupool is specified. The "no cpupool" case can be dropped, as no scheduler other than the init scheduler will ever work on cpus not associated with any cpupool. As the individual schedulers should only ever work on scheduling resources instead of individual cpus, their cpupool_online_cpumask() use should be replaced by cpupool->res_valid. Note that only with core scheduling active this might result in potential problems, as with cpu scheduling both masks are identical. Signed-off-by: Juergen Gross <jgross@suse.com> --- xen/common/sched_credit.c | 3 +-- xen/common/sched_rt.c | 4 ++-- xen/include/xen/sched-if.h | 3 --- 3 files changed, 3 insertions(+), 7 deletions(-)