Messages in this thread | | | Date | Fri, 7 Jul 2017 20:34:16 +0530 | From | Gautham R Shenoy <> | Subject | Re: [PATCH 4/5] powernv:idle: Move initialization of sibling pacas to pnv_alloc_idle_core_states |
| |
On Fri, Jul 07, 2017 at 01:16:09AM +1000, Nicholas Piggin wrote: > On Wed, 5 Jul 2017 22:08:15 +0530 > "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> wrote: > > > From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> > > > > On POWER9 DD1, in order to get around a hardware issue, we store in > > every CPU thread's paca the paca pointers of all its siblings. > > > > Move this code into pnv_alloc_idle_core_states() soon after the space > > for saving the sibling pacas is allocated. > > > > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> > > > - if (cpu_has_feature(CPU_FTR_POWER9_DD1)) { > > - int cpu; > > - > > - pr_info("powernv: idle: Saving PACA pointers of all CPUs in their thread sibling PACA\n"); > > - for_each_possible_cpu(cpu) { > > - int base_cpu = cpu_first_thread_sibling(cpu); > > - int idx = cpu_thread_in_core(cpu); > > - int i; > > - > > You could move the thread_sibling_pacas allocation to here? > > Speaking of which... core_idle_state and thread_sibling_pacas are > allocated with kmalloc_node... What happens if we take an SLB miss > in the idle wakeup code on these guys? Nothing good I think. Perhaps > we should put them into the pacas or somewhere in bolted memory.
Yes, though the SLB miss hasn't yet been encountered in practise so far!
While one can define thread_sibling_pacas in PACA, it doesn't make sense to allocate space for core_idle_state in PACA since the allocated value of the secondary threads will never be used.
What is the right way to ensure that these allocations fall in the bolted range ?
> > Good cleanup though. > > Reviewed-by: Nicholas Piggin <npiggin@gmail.com> >
| |