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=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 9C482C433ED for ; Tue, 13 Apr 2021 01:03:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3588D6102A for ; Tue, 13 Apr 2021 01:03:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3588D6102A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6D7166B0036; Mon, 12 Apr 2021 21:03:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6ACE36B006E; Mon, 12 Apr 2021 21:03:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4FEE26B0070; Mon, 12 Apr 2021 21:03:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0004.hostedemail.com [216.40.44.4]) by kanga.kvack.org (Postfix) with ESMTP id 345486B0036 for ; Mon, 12 Apr 2021 21:03:06 -0400 (EDT) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id EA9E582499A8 for ; Tue, 13 Apr 2021 01:03:05 +0000 (UTC) X-FDA: 78025544730.31.15F096C Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf20.hostedemail.com (Postfix) with ESMTP id D9B24E4 for ; Tue, 13 Apr 2021 01:03:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618275784; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NsnOZhfDDmNX8NdBm3yb2Qi8vpH9UqjQP9RovkzcARY=; b=SNEQzAlAPT+aQ60YxDF9A1iBUUmr1sXHtAEsrfNdGhf2loB6+6ib5wrjICqvnBCidFZDFb 1tHCXoFy+IsBn4JlE4ACf4KLKCJpbDRxWHucGfM5+9GVc84Z/VvKKNT/Q/ZJ8klY10wpRz zRNow3guhdZmrLhoNxCPXKnPu0rH4MY= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-339-M7XI1U6gP_evtBs7mw9ZNw-1; Mon, 12 Apr 2021 21:03:03 -0400 X-MC-Unique: M7XI1U6gP_evtBs7mw9ZNw-1 Received: by mail-qv1-f71.google.com with SMTP id p5so9096888qvr.4 for ; Mon, 12 Apr 2021 18:03:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=NsnOZhfDDmNX8NdBm3yb2Qi8vpH9UqjQP9RovkzcARY=; b=LJu+oqohSa5tYKXqP36EynclQHkncWxhvu75wQIlIyIZnzTzMFSACErCtYAynpA0zT sAZMw52eSqGRaboJbVqKIxjlNiTtG6gq2gbdRe79OXmp7zyZIJpJWLk6AZPOLqgIrOmi nY+5GsVugwKLvU3ZqDGIjqQT6MXW2LL/zHWu9Aa98ILYifXRrVjwW5Uj6fiTNjgSk1GP TM5y0+WL+l6ei3tF2V49/Zs1nchEXdoqq+9pOXGTYDPg4aj/4UyxEVQyN99me30CAVnr iK/yKP0X27YaBXrSCqoAsY/0luaevJyP9JrsHAw3AhGj8iCILHJ0gf6KVWsu9ag0hiCD EsFw== X-Gm-Message-State: AOAM531dDAOTeIy/BI5I6eU0YqqeTwc0lJ0Star0FMwCd0IeaPNZDZCD u5x034iJ8jVMr+8n0xDqpqxWQOhC4DJON/xFp9McgQgS38VH3gCfjUVBjmxM4Y2r5InT8jTyx6p ZbnBQnfT066Q= X-Received: by 2002:ac8:40d9:: with SMTP id f25mr27965008qtm.323.1618275782803; Mon, 12 Apr 2021 18:03:02 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzf+ajxx6gJ8y8Xb7tFiweNA1lCZ4uIyKIj/PrrD1+GTjvm+6qf5Zxe9z4kJ2aMGZUg27GXLw== X-Received: by 2002:ac8:40d9:: with SMTP id f25mr27964989qtm.323.1618275782525; Mon, 12 Apr 2021 18:03:02 -0700 (PDT) Received: from llong.remote.csb ([2601:191:8500:76c0::cdbc]) by smtp.gmail.com with ESMTPSA id f9sm9097847qkk.115.2021.04.12.18.03.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Apr 2021 18:03:01 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Subject: Re: [PATCH v2 5/5] mm/memcg: Optimize user context object stock access To: Shakeel Butt Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , LKML , Cgroups , Linux MM , Muchun Song , Alex Shi , Chris Down , Yafang Shao , Wei Yang , Masayoshi Mizuma , Xing Zhengjun References: <20210412225503.15119-1-longman@redhat.com> <20210412225503.15119-6-longman@redhat.com> Message-ID: <507e199e-963c-b7e2-958a-6cc61b55ca5d@redhat.com> Date: Mon, 12 Apr 2021 21:03:00 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=llong@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D9B24E4 X-Stat-Signature: onzrpzn573kj96wiqgmie5zwm4jubz8r Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618275780-781840 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/12/21 7:10 PM, Shakeel Butt wrote: > On Mon, Apr 12, 2021 at 3:55 PM Waiman Long wrote: >> Most kmem_cache_alloc() calls are from user context. With instrumentation >> enabled, the measured amount of kmem_cache_alloc() calls from non-task >> context was about 0.01% of the total. >> >> The irq disable/enable sequence used in this case to access content >> from object stock is slow. To optimize for user context access, there >> are now two object stocks for task context and interrupt context access >> respectively. >> >> The task context object stock can be accessed after disabling preemption >> which is cheap in non-preempt kernel. The interrupt context object stock >> can only be accessed after disabling interrupt. User context code can >> access interrupt object stock, but not vice versa. >> >> The mod_objcg_state() function is also modified to make sure that memcg >> and lruvec stat updates are done with interrupted disabled. >> >> The downside of this change is that there are more data stored in local >> object stocks and not reflected in the charge counter and the vmstat >> arrays. However, this is a small price to pay for better performance. >> >> Signed-off-by: Waiman Long >> Acked-by: Roman Gushchin >> --- >> mm/memcontrol.c | 73 +++++++++++++++++++++++++++++++++++++++---------- >> 1 file changed, 59 insertions(+), 14 deletions(-) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 69f728383efe..29f2df76644a 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -2229,7 +2229,8 @@ struct obj_stock { >> struct memcg_stock_pcp { >> struct mem_cgroup *cached; /* this never be root cgroup */ >> unsigned int nr_pages; >> - struct obj_stock obj; >> + struct obj_stock task_obj; >> + struct obj_stock irq_obj; >> >> struct work_struct work; >> unsigned long flags; >> @@ -2254,11 +2255,48 @@ static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, >> } >> #endif >> >> +/* >> + * Most kmem_cache_alloc() calls are from user context. The irq disable/enable >> + * sequence used in this case to access content from object stock is slow. >> + * To optimize for user context access, there are now two object stocks for >> + * task context and interrupt context access respectively. >> + * >> + * The task context object stock can be accessed by disabling preemption only >> + * which is cheap in non-preempt kernel. The interrupt context object stock >> + * can only be accessed after disabling interrupt. User context code can >> + * access interrupt object stock, but not vice versa. >> + */ >> static inline struct obj_stock *current_obj_stock(void) >> { >> struct memcg_stock_pcp *stock = this_cpu_ptr(&memcg_stock); >> >> - return &stock->obj; >> + return in_task() ? &stock->task_obj : &stock->irq_obj; >> +} >> + >> +#define get_obj_stock(flags) \ >> +({ \ >> + struct memcg_stock_pcp *stock; \ >> + struct obj_stock *obj_stock; \ >> + \ >> + if (in_task()) { \ >> + preempt_disable(); \ >> + (flags) = -1L; \ >> + stock = this_cpu_ptr(&memcg_stock); \ > The above line was missing in the previous version. > >> + obj_stock = &stock->task_obj; \ >> + } else { \ >> + local_irq_save(flags); \ >> + stock = this_cpu_ptr(&memcg_stock); \ >> + obj_stock = &stock->irq_obj; \ >> + } \ >> + obj_stock; \ >> +}) >> + >> +static inline void put_obj_stock(unsigned long flags) >> +{ >> + if (flags == -1L) >> + preempt_enable(); >> + else >> + local_irq_restore(flags); >> } >> >> /** >> @@ -2327,7 +2365,9 @@ static void drain_local_stock(struct work_struct *dummy) >> local_irq_save(flags); >> >> stock = this_cpu_ptr(&memcg_stock); >> - drain_obj_stock(&stock->obj); >> + drain_obj_stock(&stock->irq_obj); >> + if (in_task()) >> + drain_obj_stock(&stock->task_obj); >> drain_stock(stock); >> clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); >> >> @@ -3183,7 +3223,7 @@ static inline void mod_objcg_state(struct obj_cgroup *objcg, >> memcg = obj_cgroup_memcg(objcg); >> if (pgdat) >> lruvec = mem_cgroup_lruvec(memcg, pgdat); >> - __mod_memcg_lruvec_state(memcg, lruvec, idx, nr); >> + mod_memcg_lruvec_state(memcg, lruvec, idx, nr); >> rcu_read_unlock(); >> } >> >> @@ -3193,7 +3233,7 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) >> unsigned long flags; >> bool ret = false; >> >> - local_irq_save(flags); >> + stock = get_obj_stock(flags); >> >> stock = current_obj_stock(); > The above is redundant. Right. I should check the patch carefully. Will remove it. Thanks, Longman