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Message-Id: <20210312072940.598696-3-leobras.c@gmail.com>
Date: Fri, 12 Mar 2021 04:29:40 -0300
From: Leonardo Bras <leobras.c@...il.com>
To: Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Leonardo Bras <leobras.c@...il.com>,
Sandipan Das <sandipan@...ux.ibm.com>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
Logan Gunthorpe <logang@...tatee.com>,
Mike Rapoport <rppt@...nel.org>,
Bharata B Rao <bharata@...ux.ibm.com>,
Dan Williams <dan.j.williams@...el.com>,
Nicholas Piggin <npiggin@...il.com>,
Nathan Lynch <nathanl@...ux.ibm.com>,
David Hildenbrand <david@...hat.com>,
Laurent Dufour <ldufour@...ux.ibm.com>,
Scott Cheloha <cheloha@...ux.ibm.com>,
David Gibson <david@...son.dropbear.id.au>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] powerpc/mm/hash: Avoid multiple HPT resize-ups on memory hotplug
Every time a memory hotplug happens, and the memory limit crosses a 2^n
value, it may be necessary to perform HPT resizing-up, which can take
some time (over 100ms in my tests).
It usually is not an issue, but it can take some time if a lot of memory
is added to a guest with little starting memory:
Adding 256G to a 2GB guest, for example will require 8 HPT resizes.
Perform an HPT resize before memory hotplug, updating HPT to its
final size (considering a successful hotplug), taking the number of
HPT resizes to at most one per memory hotplug action.
Signed-off-by: Leonardo Bras <leobras.c@...il.com>
---
arch/powerpc/include/asm/book3s/64/hash.h | 2 ++
arch/powerpc/include/asm/sparsemem.h | 2 ++
arch/powerpc/mm/book3s64/hash_utils.c | 14 ++++++++++++++
arch/powerpc/mm/book3s64/pgtable.c | 6 ++++++
arch/powerpc/platforms/pseries/hotplug-memory.c | 6 ++++++
5 files changed, 30 insertions(+)
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index d959b0195ad9..843b0a178590 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -255,6 +255,8 @@ int hash__create_section_mapping(unsigned long start, unsigned long end,
int nid, pgprot_t prot);
int hash__remove_section_mapping(unsigned long start, unsigned long end);
+void hash_memory_batch_expand_prepare(unsigned long newsize);
+
#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_BOOK3S_64_HASH_H */
diff --git a/arch/powerpc/include/asm/sparsemem.h b/arch/powerpc/include/asm/sparsemem.h
index d072866842e4..16b5f5300c84 100644
--- a/arch/powerpc/include/asm/sparsemem.h
+++ b/arch/powerpc/include/asm/sparsemem.h
@@ -17,6 +17,8 @@ extern int remove_section_mapping(unsigned long start, unsigned long end);
extern int memory_add_physaddr_to_nid(u64 start);
#define memory_add_physaddr_to_nid memory_add_physaddr_to_nid
+void memory_batch_expand_prepare(unsigned long newsize);
+
#ifdef CONFIG_NUMA
extern int hot_add_scn_to_nid(unsigned long scn_addr);
#else
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index cfb3ec164f56..1f6aa0bf27e7 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -858,6 +858,20 @@ int hash__remove_section_mapping(unsigned long start, unsigned long end)
return rc;
}
+
+void hash_memory_batch_expand_prepare(unsigned long newsize)
+{
+ /*
+ * Resizing-up HPT should never fail, but there are some cases system starts with higher
+ * SHIFT than required, and we go through the funny case of resizing HPT down while
+ * adding memory
+ */
+
+ while (resize_hpt_for_hotplug(newsize, false) == -ENOSPC) {
+ newsize *= 2;
+ pr_warn("Hash collision while resizing HPT\n");
+ }
+}
#endif /* CONFIG_MEMORY_HOTPLUG */
static void __init hash_init_partition_table(phys_addr_t hash_table,
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 5b3a3bae21aa..f1cd8af0f67f 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -193,6 +193,12 @@ int __meminit remove_section_mapping(unsigned long start, unsigned long end)
return hash__remove_section_mapping(start, end);
}
+
+void memory_batch_expand_prepare(unsigned long newsize)
+{
+ if (!radix_enabled())
+ hash_memory_batch_expand_prepare(newsize);
+}
#endif /* CONFIG_MEMORY_HOTPLUG */
void __init mmu_partition_table_init(void)
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 8377f1f7c78e..353c71249214 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -671,6 +671,8 @@ static int dlpar_memory_add_by_count(u32 lmbs_to_add)
if (lmbs_available < lmbs_to_add)
return -EINVAL;
+ memory_batch_expand_prepare(memblock_phys_mem_size() + lmbs_to_add * drmem_lmb_size());
+
for_each_drmem_lmb(lmb) {
if (lmb->flags & DRCONF_MEM_ASSIGNED)
continue;
@@ -734,6 +736,8 @@ static int dlpar_memory_add_by_index(u32 drc_index)
pr_info("Attempting to hot-add LMB, drc index %x\n", drc_index);
+ memory_batch_expand_prepare(memblock_phys_mem_size() +
+ drmem_info->n_lmbs * drmem_lmb_size());
lmb_found = 0;
for_each_drmem_lmb(lmb) {
if (lmb->drc_index == drc_index) {
@@ -788,6 +792,8 @@ static int dlpar_memory_add_by_ic(u32 lmbs_to_add, u32 drc_index)
if (lmbs_available < lmbs_to_add)
return -EINVAL;
+ memory_batch_expand_prepare(memblock_phys_mem_size() + lmbs_to_add * drmem_lmb_size());
+
for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
if (lmb->flags & DRCONF_MEM_ASSIGNED)
continue;
--
2.29.2
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