[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen: schedule: allow dom0 vCPUs to be re-pinned when dom0_vcpus_pin is set
On 05/12/12 06:02, Matt Wilson wrote: > An administrator may want Xen to pin dom0 vCPUs to pCPUs 1:1 at boot, > but still have the flexibility to change the configuration later. > There's no logic that keys off of domain->is_pinned outside of > sched_init_vcpu() and vcpu_set_affinity(). By adjusting the > is_pinned_vcpu() macro to only check for a single CPU set in the > cpu_affinity mask, dom0 vCPUs can safely be re-pinned after the system > boots. Sadly this patch will break things. There are certain callers of is_pinned_vcpu() which rely on the value to allow access to certain power related MSRs, which is where the requirement for never permitting an update of the affinity mask comes from. When I encountered this problem before, I considered implementing dom0_vcpu_pin=dynamic (or name to suit) which sets up an identity pin at create time, but leaves is_pinned as false. ~Andrew > > Signed-off-by: Matt Wilson <msw@xxxxxxxxxx> > > diff -r 29247e44df47 -r 2614dd8be3a0 docs/misc/xen-command-line.markdown > --- a/docs/misc/xen-command-line.markdown Fri Nov 30 21:51:17 2012 +0000 > +++ b/docs/misc/xen-command-line.markdown Wed Dec 05 05:48:23 2012 +0000 > @@ -453,7 +453,7 @@ Practices](http://wiki.xen.org/wiki/Xen_ > > > Default: `false` > > -Pin dom0 vcpus to their respective pcpus > +Initially pin dom0 vcpus to their respective pcpus > > ### e820-mtrr-clip > > `= <boolean>` > diff -r 29247e44df47 -r 2614dd8be3a0 xen/common/domain.c > --- a/xen/common/domain.c Fri Nov 30 21:51:17 2012 +0000 > +++ b/xen/common/domain.c Wed Dec 05 05:48:23 2012 +0000 > @@ -45,10 +45,6 @@ > /* xen_processor_pmbits: xen control Cx, Px, ... */ > unsigned int xen_processor_pmbits = XEN_PROCESSOR_PM_PX; > > -/* opt_dom0_vcpus_pin: If true, dom0 VCPUs are pinned. */ > -bool_t opt_dom0_vcpus_pin; > -boolean_param("dom0_vcpus_pin", opt_dom0_vcpus_pin); > - > /* Protect updates/reads (resp.) of domain_list and domain_hash. */ > DEFINE_SPINLOCK(domlist_update_lock); > DEFINE_RCU_READ_LOCK(domlist_read_lock); > @@ -235,7 +231,6 @@ struct domain *domain_create( > > if ( domid == 0 ) > { > - d->is_pinned = opt_dom0_vcpus_pin; > d->disable_migrate = 1; > } > > diff -r 29247e44df47 -r 2614dd8be3a0 xen/common/schedule.c > --- a/xen/common/schedule.c Fri Nov 30 21:51:17 2012 +0000 > +++ b/xen/common/schedule.c Wed Dec 05 05:48:23 2012 +0000 > @@ -52,6 +52,11 @@ boolean_param("sched_smt_power_savings", > * */ > int sched_ratelimit_us = SCHED_DEFAULT_RATELIMIT_US; > integer_param("sched_ratelimit_us", sched_ratelimit_us); > + > +/* opt_dom0_vcpus_pin: If true, dom0 VCPUs are pinned at boot. */ > +bool_t opt_dom0_vcpus_pin; > +boolean_param("dom0_vcpus_pin", opt_dom0_vcpus_pin); > + > /* Various timer handlers. */ > static void s_timer_fn(void *unused); > static void vcpu_periodic_timer_fn(void *data); > @@ -194,7 +199,8 @@ int sched_init_vcpu(struct vcpu *v, unsi > * domain-0 VCPUs, are pinned onto their respective physical CPUs. > */ > v->processor = processor; > - if ( is_idle_domain(d) || d->is_pinned ) > + > + if ( is_idle_domain(d) || (d->domain_id == 0 && opt_dom0_vcpus_pin) ) > cpumask_copy(v->cpu_affinity, cpumask_of(processor)); > else > cpumask_setall(v->cpu_affinity); > @@ -595,8 +601,6 @@ int vcpu_set_affinity(struct vcpu *v, co > cpumask_t online_affinity; > cpumask_t *online; > > - if ( v->domain->is_pinned ) > - return -EINVAL; > online = VCPU2ONLINE(v); > cpumask_and(&online_affinity, affinity, online); > if ( cpumask_empty(&online_affinity) ) > diff -r 29247e44df47 -r 2614dd8be3a0 xen/include/xen/sched.h > --- a/xen/include/xen/sched.h Fri Nov 30 21:51:17 2012 +0000 > +++ b/xen/include/xen/sched.h Wed Dec 05 05:48:23 2012 +0000 > @@ -292,8 +292,6 @@ struct domain > enum { DOMDYING_alive, DOMDYING_dying, DOMDYING_dead } is_dying; > /* Domain is paused by controller software? */ > bool_t is_paused_by_controller; > - /* Domain's VCPUs are pinned 1:1 to physical CPUs? */ > - bool_t is_pinned; > > /* Are any VCPUs polling event channels (SCHEDOP_poll)? */ > #if MAX_VIRT_CPUS <= BITS_PER_LONG > @@ -713,8 +711,7 @@ void watchdog_domain_destroy(struct doma > > #define is_hvm_domain(d) ((d)->is_hvm) > #define is_hvm_vcpu(v) (is_hvm_domain(v->domain)) > -#define is_pinned_vcpu(v) ((v)->domain->is_pinned || \ > - cpumask_weight((v)->cpu_affinity) == 1) > +#define is_pinned_vcpu(v) (cpumask_weight((v)->cpu_affinity) == 1) > #ifdef HAS_PASSTHROUGH > #define need_iommu(d) ((d)->need_iommu) > #else > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel -- Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer T: +44 (0)1223 225 900, http://www.citrix.com _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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