On 02/04/2022, 18:35:15, Christophe Leroy wrote:
>
>
> Le 05/08/2020 à 15:35, Laurent Dufour a écrit :
>> All the LMB from the same set of ibm,dynamic-memory-v2 property are
>> sharing the same NUMA node. Don't compute that node for each one.
>>
>> Tested on a system with 1022 LMBs spread on 4 NUMA nodes, only 4 calls to
>> lmb_set_nid() have been made instead of 1022.
>>
>> This should prevent some soft lockups when starting large guests
>>
>> Code has meaning only if CONFIG_MEMORY_HOTPLUG is set, otherwise the nid
>> field is not present in the drmem_lmb structure.
>>
>> Signed-off-by: Laurent Dufour <lduf...@linux.ibm.com>
>
> It looks like this patch was superseded by e5e179aa3a39 ("pseries/drmem:
> don't cache node id in drmem_lmb struct").
That patch has been superseded and can be dropped.
Thanks,
Laurent.
> If not, anyway it conflicts with that patch so it has to be rebased.
>
> Thanks
> Christophe
>
>
>> ---
>> arch/powerpc/mm/drmem.c | 25 ++++++++++++++++++++++++-
>> 1 file changed, 24 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/mm/drmem.c b/arch/powerpc/mm/drmem.c
>> index b2eeea39684c..c11b6ec99ea3 100644
>> --- a/arch/powerpc/mm/drmem.c
>> +++ b/arch/powerpc/mm/drmem.c
>> @@ -402,6 +402,9 @@ static void __init init_drmem_v2_lmbs(const __be32
>> *prop)
>> const __be32 *p;
>> u32 i, j, lmb_sets;
>> int lmb_index;
>> +#ifdef CONFIG_MEMORY_HOTPLUG
>> + struct drmem_lmb *first = NULL;
>> +#endif
>> lmb_sets = of_read_number(prop++, 1);
>> if (lmb_sets == 0)
>> @@ -426,6 +429,15 @@ static void __init init_drmem_v2_lmbs(const __be32
>> *prop)
>> for (i = 0; i < lmb_sets; i++) {
>> read_drconf_v2_cell(&dr_cell, &p);
>> +#ifdef CONFIG_MEMORY_HOTPLUG
>> + /*
>> + * Fetch the NUMA node id for the fist set or if the
>> + * associativity index is different from the previous set.
>> + */
>> + if (first && dr_cell.aa_index != first->aa_index)
>> + first = NULL;
>> +#endif
>> +
>> for (j = 0; j < dr_cell.seq_lmbs; j++) {
>> lmb = &drmem_info->lmbs[lmb_index++];
>> @@ -438,7 +450,18 @@ static void __init init_drmem_v2_lmbs(const __be32
>> *prop)
>> lmb->aa_index = dr_cell.aa_index;
>> lmb->flags = dr_cell.flags;
>> - lmb_set_nid(lmb);
>> +#ifdef CONFIG_MEMORY_HOTPLUG
>> + /*
>> + * All the LMB in the set share the same NUMA
>> + * associativity property. So read that node only once.
>> + */
>> + if (!first) {
>> + lmb_set_nid(lmb);
>> + first = lmb;
>> + } else {
>> + lmb->nid = first->nid;
>> + }
>> +#endif
>> }
>> }
>> }
