Re: [PATCH, RFC] improved hacks to allow -rt to run kernbench onPOWER

From: Benjamin Herrenschmidt
Date: Sat Nov 10 2007 - 23:00:04 EST


> Removed this as well, also seemed to work. Please note, however, that
> this is just running kernbench. But this did seem to get rid of some
> of the warnings as well. ;-) Now only have the xics_startup() warning.
>
> > Overall, looks fine !
>
> I bet that there are more gotchas lurking in there somewhere, but in
> the meantime here is the updated patch.
>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> ---

Well, I suppose the patch could go in, maybe with some ifdef's around
the bits in _switch_to, there's little point in doing that on non-rt
kernels.

Ben.

> arch/powerpc/kernel/process.c | 16 ++++++++++++++++
> arch/powerpc/kernel/prom.c | 2 +-
> arch/powerpc/mm/tlb_64.c | 5 ++++-
> arch/powerpc/platforms/pseries/eeh.c | 2 +-
> drivers/of/base.c | 2 +-
> include/asm-powerpc/tlb.h | 5 ++++-
> include/asm-powerpc/tlbflush.h | 15 ++++++++++-----
> 7 files changed, 37 insertions(+), 10 deletions(-)
>
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/kernel/process.c linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/process.c
> --- linux-2.6.23.1-rt4/arch/powerpc/kernel/process.c 2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/process.c 2007-11-09 13:24:46.000000000 -0800
> @@ -245,6 +245,8 @@ struct task_struct *__switch_to(struct t
> struct thread_struct *new_thread, *old_thread;
> unsigned long flags;
> struct task_struct *last;
> + struct ppc64_tlb_batch *batch;
> + int hadbatch;
>
> #ifdef CONFIG_SMP
> /* avoid complexity of lazy save/restore of fpu
> @@ -325,6 +327,15 @@ struct task_struct *__switch_to(struct t
> }
> #endif
>
> + batch = &__get_cpu_var(ppc64_tlb_batch);
> + if (batch->active) {
> + hadbatch = 1;
> + if (batch->index) {
> + __flush_tlb_pending(batch);
> + }
> + batch->active = 0;
> + }
> +
> local_irq_save(flags);
>
> account_system_vtime(current);
> @@ -335,6 +346,11 @@ struct task_struct *__switch_to(struct t
>
> local_irq_restore(flags);
>
> + if (hadbatch) {
> + batch = &__get_cpu_var(ppc64_tlb_batch);
> + batch->active = 1;
> + }
> +
> return last;
> }
>
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/kernel/prom.c linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/prom.c
> --- linux-2.6.23.1-rt4/arch/powerpc/kernel/prom.c 2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/prom.c 2007-10-28 13:37:23.000000000 -0700
> @@ -80,7 +80,7 @@ struct boot_param_header *initial_boot_p
>
> extern struct device_node *allnodes; /* temporary while merging */
>
> -extern rwlock_t devtree_lock; /* temporary while merging */
> +extern raw_rwlock_t devtree_lock; /* temporary while merging */
>
> /* export that to outside world */
> struct device_node *of_chosen;
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/mm/tlb_64.c linux-2.6.23.1-rt4-fix/arch/powerpc/mm/tlb_64.c
> --- linux-2.6.23.1-rt4/arch/powerpc/mm/tlb_64.c 2007-10-27 22:20:57.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/mm/tlb_64.c 2007-11-08 16:49:04.000000000 -0800
> @@ -133,7 +133,7 @@ void pgtable_free_tlb(struct mmu_gather
> void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
> pte_t *ptep, unsigned long pte, int huge)
> {
> - struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
> + struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
> unsigned long vsid, vaddr;
> unsigned int psize;
> real_pte_t rpte;
> @@ -180,6 +180,7 @@ void hpte_need_flush(struct mm_struct *m
> */
> if (!batch->active) {
> flush_hash_page(vaddr, rpte, psize, 0);
> + put_cpu_var(ppc64_tlb_batch);
> return;
> }
>
> @@ -212,12 +213,14 @@ void hpte_need_flush(struct mm_struct *m
> */
> if (machine_is(celleb)) {
> __flush_tlb_pending(batch);
> + put_cpu_var(ppc64_tlb_batch);
> return;
> }
> #endif /* CONFIG_PREEMPT_RT */
>
> if (i >= PPC64_TLB_BATCH_NR)
> __flush_tlb_pending(batch);
> + put_cpu_var(ppc64_tlb_batch);
> }
>
> /*
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/platforms/pseries/eeh.c linux-2.6.23.1-rt4-fix/arch/powerpc/platforms/pseries/eeh.c
> --- linux-2.6.23.1-rt4/arch/powerpc/platforms/pseries/eeh.c 2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/arch/powerpc/platforms/pseries/eeh.c 2007-10-28 15:43:54.000000000 -0700
> @@ -97,7 +97,7 @@ int eeh_subsystem_enabled;
> EXPORT_SYMBOL(eeh_subsystem_enabled);
>
> /* Lock to avoid races due to multiple reports of an error */
> -static DEFINE_SPINLOCK(confirm_error_lock);
> +static DEFINE_RAW_SPINLOCK(confirm_error_lock);
>
> /* Buffer for reporting slot-error-detail rtas calls. Its here
> * in BSS, and not dynamically alloced, so that it ends up in
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/drivers/of/base.c linux-2.6.23.1-rt4-fix/drivers/of/base.c
> --- linux-2.6.23.1-rt4/drivers/of/base.c 2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/drivers/of/base.c 2007-10-28 13:38:36.000000000 -0700
> @@ -25,7 +25,7 @@ struct device_node *allnodes;
> /* use when traversing tree through the allnext, child, sibling,
> * or parent members of struct device_node.
> */
> -DEFINE_RWLOCK(devtree_lock);
> +DEFINE_RAW_RWLOCK(devtree_lock);
>
> int of_n_addr_cells(struct device_node *np)
> {
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/include/asm-powerpc/tlbflush.h linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlbflush.h
> --- linux-2.6.23.1-rt4/include/asm-powerpc/tlbflush.h 2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlbflush.h 2007-11-08 17:11:18.000000000 -0800
> @@ -109,18 +109,23 @@ extern void hpte_need_flush(struct mm_st
>
> static inline void arch_enter_lazy_mmu_mode(void)
> {
> - struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
> + struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
>
> batch->active = 1;
> + put_cpu_var(ppc64_tlb_batch);
> }
>
> static inline void arch_leave_lazy_mmu_mode(void)
> {
> - struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
> + struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
>
> - if (batch->index)
> - __flush_tlb_pending(batch);
> - batch->active = 0;
> + if (batch->active) {
> + if (batch->index) {
> + __flush_tlb_pending(batch);
> + }
> + batch->active = 0;
> + }
> + put_cpu_var(ppc64_tlb_batch);
> }
>
> #define arch_flush_lazy_mmu_mode() do {} while (0)
> diff -urpNa -X dontdiff linux-2.6.23.1-rt4/include/asm-powerpc/tlb.h linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlb.h
> --- linux-2.6.23.1-rt4/include/asm-powerpc/tlb.h 2007-10-12 09:43:44.000000000 -0700
> +++ linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlb.h 2007-10-28 11:36:05.000000000 -0700
> @@ -44,8 +44,11 @@ static inline void tlb_flush(struct mmu_
> * pages are going to be freed and we really don't want to have a CPU
> * access a freed page because it has a stale TLB
> */
> - if (tlbbatch->index)
> + if (tlbbatch->index) {
> + preempt_disable();
> __flush_tlb_pending(tlbbatch);
> + preempt_enable();
> + }
>
> pte_free_finish();
> }

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