Messages in this thread Patch in this message |  | | From | Laurent Dufour <> | Subject | [PATCH v2] powerpc/drmem: Don't compute the NUMA node for each LMB | Date | Wed, 5 Aug 2020 15:35:02 +0200 |
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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 <ldufour@linux.ibm.com> --- 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 } } } -- 2.28.0
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