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Fri, 30 Apr 2021 07:37:00 -0700 (PDT) Received: from li-908e0a4c-2250-11b2-a85c-f027e903211b.ibm.com.com ([2804:14c:482:7b04::1001]) by smtp.gmail.com with ESMTPSA id 190sm1532560qki.115.2021.04.30.07.36.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Apr 2021 07:37:00 -0700 (PDT) From: Leonardo Bras To: Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Leonardo Bras , Sandipan Das , Mike Rapoport , Andrew Morton , "Aneesh Kumar K.V" , Nicholas Piggin , Nathan Lynch , David Hildenbrand , Scott Cheloha , Laurent Dufour Subject: [PATCH v2 2/3] powerpc/mm/hash: Avoid multiple HPT resize-ups on memory hotplug Date: Fri, 30 Apr 2021 11:36:08 -0300 Message-Id: <20210430143607.135005-3-leobras.c@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210430143607.135005-1-leobras.c@gmail.com> References: <20210430143607.135005-1-leobras.c@gmail.com> MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 Reviewed-by: David Gibson --- arch/powerpc/include/asm/book3s/64/hash.h | 2 ++ arch/powerpc/mm/book3s64/hash_utils.c | 20 +++++++++++++++++++ .../platforms/pseries/hotplug-memory.c | 9 +++++++++ 3 files changed, 31 insertions(+) diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h index d959b0195ad9..fad4af8b8543 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_batch_expand_prepare(unsigned long newsize); + #endif /* !__ASSEMBLY__ */ #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_BOOK3S_64_HASH_H */ diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 608e4ed397a9..3fa395b3fe57 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -859,6 +859,26 @@ int hash__remove_section_mapping(unsigned long start, unsigned long end) return rc; } + +void hash_batch_expand_prepare(unsigned long newsize) +{ + const u64 starting_size = ppc64_pft_size; + + /* + * 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"); + + /* Do not try to resize to the starting size, or bigger value */ + if (htab_shift_for_mem_size(newsize) >= starting_size) + break; + } +} #endif /* CONFIG_MEMORY_HOTPLUG */ static void __init hash_init_partition_table(phys_addr_t hash_table, diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c index 8377f1f7c78e..48b2cfe4ce69 100644 --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include @@ -671,6 +672,10 @@ static int dlpar_memory_add_by_count(u32 lmbs_to_add) if (lmbs_available < lmbs_to_add) return -EINVAL; + if (!radix_enabled()) + hash_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; @@ -788,6 +793,10 @@ static int dlpar_memory_add_by_ic(u32 lmbs_to_add, u32 drc_index) if (lmbs_available < lmbs_to_add) return -EINVAL; + if (!radix_enabled()) + hash_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;