From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31593C433ED for ; Fri, 30 Apr 2021 14:37:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9927613D9 for ; Fri, 30 Apr 2021 14:37:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233005AbhD3OiM (ORCPT ); Fri, 30 Apr 2021 10:38:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230351AbhD3OiJ (ORCPT ); Fri, 30 Apr 2021 10:38:09 -0400 Received: from mail-qk1-x72e.google.com (mail-qk1-x72e.google.com [IPv6:2607:f8b0:4864:20::72e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9B320C06174A for ; Fri, 30 Apr 2021 07:37:19 -0700 (PDT) Received: by mail-qk1-x72e.google.com with SMTP id v20so15968291qkv.5 for ; Fri, 30 Apr 2021 07:37:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=sbxM0d7iVP2AFAHnR5wZZv7UonG+3h5RRC/2YZAfwa4=; b=W2yHmrJlKhqzfDfSmZkFdYjO7Q/7VDJpMrkZ9dkSwloDYkRUUgzWLpaosA11jGrl8/ EKIu8x9KNrhqigpOeWNNSyDsC/pQ7qdBBSHRcA8VN4N+zqpovc7B8sOeW+sP2nbN3B8K xTkt2U+tO3aLHjEN20dTP1tzDwWkj/2u381y3T2/yZZkCjnJb+jtdaSduzGhMv7ZS/cs mfrHzRamccNEiHMFHAoLj15223nRtWDhd/zRxqnSOijXdCsdRrWYBpSrUdqCTgDMew8t gAprsO152s38k4sKUZXHHxP3pqlk9cz79wyipVvMMYkSZWEHzbUqdS5TJvaWr943Otam OTCA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=sbxM0d7iVP2AFAHnR5wZZv7UonG+3h5RRC/2YZAfwa4=; b=sj1Mo8J0/zLWi2HoOG16vymgduJVb0pbBBquy7ugtd4NAE/ktMvXiZ72t1p7GOyES/ g+7SpUH0fg5nKFU4PBzab/zLxlDa2EemXHp2rxwgf5gRCmD06Yjw0ym6xGZad/UAggLR moT7uc2DYrtbaHs0hBG2B9wNkdrkov5WLYaVNFEkgSEnGQBioo5ooE0baZvjaEDy7OAz o9ERIQhfQTNEZ2CiRInMtBxH2POT9Rq3yGHiXqYFzgV6k8MEB6Q5EetprWfFMsE5DLh+ IhXrF0QB6/j7Lew7te8Dqm+IVohQieelITzVVJa5wfBRCtku/342mJ3IRKlGztrdab+x MbPw== X-Gm-Message-State: AOAM533+4VTbG7VujQ/cW+1LqETH8Jm6B/doBE78cwMg8Z/n8xsfYUyX VMYqJzFXFXAvX+TO0m2aqmE= X-Google-Smtp-Source: ABdhPJyojzoDSFGiBlevl0kCCOc/+/Da+PIfH24WUxdcJM8zJY5iN9DVGHlJXjTAtjom3orRq1WWlA== X-Received: by 2002:a37:9802:: with SMTP id a2mr5961659qke.473.1619793438928; Fri, 30 Apr 2021 07:37:18 -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.115.2021.04.30.07.37.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Apr 2021 07:37:18 -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 Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/3] powerpc/mm/hash: Avoid multiple HPT resize-downs on memory hotunplug Date: Fri, 30 Apr 2021 11:36:10 -0300 Message-Id: <20210430143607.135005-4-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 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During memory hotunplug, after each LMB is removed, the HPT may be resized-down if it would map a max of 4 times the current amount of memory. (2 shifts, due to introduced histeresis) It usually is not an issue, but it can take a lot of time if HPT resizing-down fails. This happens because resize-down failures usually repeat at each LMB removal, until there are no more bolted entries conflict, which can take a while to happen. This can be solved by doing a single HPT resize at the end of memory hotunplug, after all requested entries are removed. To make this happen, it's necessary to temporarily disable all HPT resize-downs before hotunplug, re-enable them after hotunplug ends, and then resize-down HPT to the current memory size. As an example, hotunplugging 256GB from a 385GB guest took 621s without this patch, and 100s after applied. Signed-off-by: Leonardo Bras --- arch/powerpc/include/asm/book3s/64/hash.h | 2 + arch/powerpc/mm/book3s64/hash_utils.c | 45 +++++++++++++++++-- .../platforms/pseries/hotplug-memory.c | 26 +++++++++++ 3 files changed, 70 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h index fad4af8b8543..6cd66e7e98c9 100644 --- a/arch/powerpc/include/asm/book3s/64/hash.h +++ b/arch/powerpc/include/asm/book3s/64/hash.h @@ -256,6 +256,8 @@ int hash__create_section_mapping(unsigned long start, unsigned long end, int hash__remove_section_mapping(unsigned long start, unsigned long end); void hash_batch_expand_prepare(unsigned long newsize); +void hash_batch_shrink_begin(void); +void hash_batch_shrink_end(void); #endif /* !__ASSEMBLY__ */ #endif /* __KERNEL__ */ diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 3fa395b3fe57..73ecd0f61acd 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -795,6 +795,9 @@ static unsigned long __init htab_get_table_size(void) } #ifdef CONFIG_MEMORY_HOTPLUG + +static DEFINE_MUTEX(hpt_resize_down_lock); + static int resize_hpt_for_hotplug(unsigned long new_mem_size, bool shrinking) { unsigned target_hpt_shift; @@ -805,7 +808,7 @@ static int resize_hpt_for_hotplug(unsigned long new_mem_size, bool shrinking) target_hpt_shift = htab_shift_for_mem_size(new_mem_size); if (shrinking) { - + int ret; /* * To avoid lots of HPT resizes if memory size is fluctuating * across a boundary, we deliberately have some hysterisis @@ -818,10 +821,20 @@ static int resize_hpt_for_hotplug(unsigned long new_mem_size, bool shrinking) if (target_hpt_shift >= ppc64_pft_size - 1) return 0; - } else if (target_hpt_shift <= ppc64_pft_size) { - return 0; + /* When batch removing entries, only resizes HPT at the end. */ + + if (!mutex_trylock(&hpt_resize_down_lock)) + return 0; + + ret = mmu_hash_ops.resize_hpt(target_hpt_shift); + + mutex_unlock(&hpt_resize_down_lock); + return ret; } + if (target_hpt_shift <= ppc64_pft_size) + return 0; + return mmu_hash_ops.resize_hpt(target_hpt_shift); } @@ -879,6 +892,32 @@ void hash_batch_expand_prepare(unsigned long newsize) break; } } + +void hash_batch_shrink_begin(void) +{ + /* Disable HPT resize-down during hot-unplug */ + mutex_lock(&hpt_resize_down_lock); +} + +void hash_batch_shrink_end(void) +{ + const u64 starting_size = ppc64_pft_size; + unsigned long newsize; + + newsize = memblock_phys_mem_size(); + /* Resize to smallest SHIFT possible */ + while (resize_hpt_for_hotplug(newsize, true) == -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; + } + + /* Re-enables HPT resize-down after hot-unplug */ + mutex_unlock(&hpt_resize_down_lock); +} #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 48b2cfe4ce69..44bc50d72353 100644 --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -426,6 +426,9 @@ static int dlpar_memory_remove_by_count(u32 lmbs_to_remove) return -EINVAL; } + if (!radix_enabled()) + hash_batch_shrink_begin(); + for_each_drmem_lmb(lmb) { rc = dlpar_remove_lmb(lmb); if (rc) @@ -471,6 +474,9 @@ static int dlpar_memory_remove_by_count(u32 lmbs_to_remove) rc = 0; } + if (!radix_enabled()) + hash_batch_shrink_end(); + return rc; } @@ -533,6 +539,9 @@ static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index) if (lmbs_available < lmbs_to_remove) return -EINVAL; + if (!radix_enabled()) + hash_batch_shrink_begin(); + for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) { if (!(lmb->flags & DRCONF_MEM_ASSIGNED)) continue; @@ -573,6 +582,9 @@ static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index) } } + if (!radix_enabled()) + hash_batch_shrink_end(); + return rc; } @@ -703,6 +715,9 @@ static int dlpar_memory_add_by_count(u32 lmbs_to_add) if (lmbs_added != lmbs_to_add) { pr_err("Memory hot-add failed, removing any added LMBs\n"); + if (!radix_enabled()) + hash_batch_shrink_begin(); + for_each_drmem_lmb(lmb) { if (!drmem_lmb_reserved(lmb)) continue; @@ -716,6 +731,10 @@ static int dlpar_memory_add_by_count(u32 lmbs_to_add) drmem_remove_lmb_reservation(lmb); } + + if (!radix_enabled()) + hash_batch_shrink_end(); + rc = -EINVAL; } else { for_each_drmem_lmb(lmb) { @@ -817,6 +836,9 @@ static int dlpar_memory_add_by_ic(u32 lmbs_to_add, u32 drc_index) if (rc) { pr_err("Memory indexed-count-add failed, removing any added LMBs\n"); + if (!radix_enabled()) + hash_batch_shrink_begin(); + for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) { if (!drmem_lmb_reserved(lmb)) continue; @@ -830,6 +852,10 @@ static int dlpar_memory_add_by_ic(u32 lmbs_to_add, u32 drc_index) drmem_remove_lmb_reservation(lmb); } + + if (!radix_enabled()) + hash_batch_shrink_end(); + rc = -EINVAL; } else { for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) { -- 2.30.2