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,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 23E38C43460 for ; Fri, 23 Apr 2021 16:52:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9061613C2 for ; Fri, 23 Apr 2021 16:52:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243135AbhDWQxO (ORCPT ); Fri, 23 Apr 2021 12:53:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:24476 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230072AbhDWQxK (ORCPT ); Fri, 23 Apr 2021 12:53:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619196753; 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=enManHEzv32cqVRF46CePltyDkAaNIcE1LHVBh9NKfk=; b=cN95ag1KU0DekGdbbouEnDyAhDBvvOIABqLS21gxxEMiaTHuUUq3xzZCBJ4qVjZtFPzKtV NWErz/HO7IP+Pzy3lS+ZEnag24hmps3Y18JAWdeAyXgZLJ94XAvCp4rEdEhiN14HBnLVEc fFP0sN5ZL0BPG4bAvv7PkOpf4zMXR+w= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-594-IR8VxTPDMUWAfRInijaTKA-1; Fri, 23 Apr 2021 12:52:31 -0400 X-MC-Unique: IR8VxTPDMUWAfRInijaTKA-1 Received: by mail-qt1-f198.google.com with SMTP id h12-20020ac8744c0000b02901ba644d864fso7913112qtr.8 for ; Fri, 23 Apr 2021 09:52:31 -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=enManHEzv32cqVRF46CePltyDkAaNIcE1LHVBh9NKfk=; b=GFsEDwv5uMlTa2/XWXn3zu5HaP9UrMJMh4Uds50HmCAkxwzLpiMvLwa4Y7Vo37R7cg kcsKAkSvaB50x4vqQmuPDDbGLK0p7WRUx5IVlaH0KvwrauDIwGpOdPG4CkKvVif5lzYT 3lzaH/SE4ddM27YGaktzFnEbQxXpRHTM2Ia2nxscxgNlu6mTwV0KfkiEK5kpWl+Ggwes mWlJ+OQNJRS3U7xYW9w2mq1o59vP3MQLBYiK3YICke5T0ZdGRxEss8Xa9xhIXOpfMbRy CKUExaN1KaHgLO/BWxFKii/2Idzxs51F7RFTupHciLy6UIuVh8fO8Z18NDtvRWwq+uJa SD1Q== X-Gm-Message-State: AOAM533zXbyM7nDCak5JBth2mykNSsEQrFJPRYeDIrzpOluIXB3p9lXV cDxKgD2Wsd+T/8HiLxU8zGcA7j34STiRw/hilnGmoDDssvMAq4R7RqEyQDE6JOcFxNVoaJi2e/8 aRLL5abW3oMplsJTU7lL3mbmz X-Received: by 2002:a37:610f:: with SMTP id v15mr5225542qkb.217.1619196751461; Fri, 23 Apr 2021 09:52:31 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxxslCgP6jpThSvanZXOk3vTRKMvnGz/iORN8PDsijPju3+a1N78M/PLK/NmsHFZInr7A6udA== X-Received: by 2002:a37:610f:: with SMTP id v15mr5225521qkb.217.1619196751257; Fri, 23 Apr 2021 09:52:31 -0700 (PDT) Received: from llong.remote.csb ([2601:191:8500:76c0::cdbc]) by smtp.gmail.com with ESMTPSA id a30sm5232405qtn.4.2021.04.23.09.52.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 23 Apr 2021 09:52:30 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Subject: Re: [PATCH-next v5 2/4] mm/memcg: Cache vmstat data in percpu memcg_stock_pcp To: Roman Gushchin , Waiman Long Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Muchun Song , Alex Shi , Chris Down , Yafang Shao , Wei Yang , Masayoshi Mizuma , Xing Zhengjun , Matthew Wilcox References: <20210420192907.30880-1-longman@redhat.com> <20210420192907.30880-3-longman@redhat.com> Message-ID: <6a261f7f-a127-a757-9f4c-4231823911c1@redhat.com> Date: Fri, 23 Apr 2021 12:52:29 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/22/21 9:56 PM, Roman Gushchin wrote: > On Thu, Apr 22, 2021 at 12:58:52PM -0400, Waiman Long wrote: >> On 4/21/21 7:28 PM, Roman Gushchin wrote: >>> On Tue, Apr 20, 2021 at 03:29:05PM -0400, Waiman Long wrote: >>>> Before the new slab memory controller with per object byte charging, >>>> charging and vmstat data update happen only when new slab pages are >>>> allocated or freed. Now they are done with every kmem_cache_alloc() >>>> and kmem_cache_free(). This causes additional overhead for workloads >>>> that generate a lot of alloc and free calls. >>>> >>>> The memcg_stock_pcp is used to cache byte charge for a specific >>>> obj_cgroup to reduce that overhead. To further reducing it, this patch >>>> makes the vmstat data cached in the memcg_stock_pcp structure as well >>>> until it accumulates a page size worth of update or when other cached >>>> data change. Caching the vmstat data in the per-cpu stock eliminates two >>>> writes to non-hot cachelines for memcg specific as well as memcg-lruvecs >>>> specific vmstat data by a write to a hot local stock cacheline. >>>> >>>> On a 2-socket Cascade Lake server with instrumentation enabled and this >>>> patch applied, it was found that about 20% (634400 out of 3243830) >>>> of the time when mod_objcg_state() is called leads to an actual call >>>> to __mod_objcg_state() after initial boot. When doing parallel kernel >>>> build, the figure was about 17% (24329265 out of 142512465). So caching >>>> the vmstat data reduces the number of calls to __mod_objcg_state() >>>> by more than 80%. >>>> >>>> Signed-off-by: Waiman Long >>>> Reviewed-by: Shakeel Butt >>>> --- >>>> mm/memcontrol.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++-- >>>> 1 file changed, 83 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>> index 7cd7187a017c..292b4783b1a7 100644 >>>> --- a/mm/memcontrol.c >>>> +++ b/mm/memcontrol.c >>>> @@ -782,8 +782,9 @@ void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val) >>>> rcu_read_unlock(); >>>> } >>>> -void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, >>>> - enum node_stat_item idx, int nr) >>>> +static inline void mod_objcg_mlstate(struct obj_cgroup *objcg, >>>> + struct pglist_data *pgdat, >>>> + enum node_stat_item idx, int nr) >>>> { >>>> struct mem_cgroup *memcg; >>>> struct lruvec *lruvec; >>>> @@ -791,7 +792,7 @@ void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, >>>> rcu_read_lock(); >>>> memcg = obj_cgroup_memcg(objcg); >>>> lruvec = mem_cgroup_lruvec(memcg, pgdat); >>>> - mod_memcg_lruvec_state(lruvec, idx, nr); >>>> + __mod_memcg_lruvec_state(lruvec, idx, nr); >>>> rcu_read_unlock(); >>>> } >>>> @@ -2059,7 +2060,10 @@ struct memcg_stock_pcp { >>>> #ifdef CONFIG_MEMCG_KMEM >>>> struct obj_cgroup *cached_objcg; >>>> + struct pglist_data *cached_pgdat; >>> I wonder if we want to have per-node counters instead? >>> That would complicate the initialization of pcp stocks a bit, >>> but might shave off some additional cpu time. >>> But we can do it later too. >>> >> A per node counter will certainly complicate the code and reduce the >> performance benefit too. > Hm, why? We wouldn't need to flush the stock if the release happens > on some other cpu not matching the current pgdat. I had actually experimented with just caching vmstat data for the local node only. It turned out the hit rate was a bit lower. That is why I keep the current approach and I need to do further investigation on a better approach. Cheers, Longman From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH-next v5 2/4] mm/memcg: Cache vmstat data in percpu memcg_stock_pcp Date: Fri, 23 Apr 2021 12:52:29 -0400 Message-ID: <6a261f7f-a127-a757-9f4c-4231823911c1@redhat.com> References: <20210420192907.30880-1-longman@redhat.com> <20210420192907.30880-3-longman@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619196753; 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=enManHEzv32cqVRF46CePltyDkAaNIcE1LHVBh9NKfk=; b=cN95ag1KU0DekGdbbouEnDyAhDBvvOIABqLS21gxxEMiaTHuUUq3xzZCBJ4qVjZtFPzKtV NWErz/HO7IP+Pzy3lS+ZEnag24hmps3Y18JAWdeAyXgZLJ94XAvCp4rEdEhiN14HBnLVEc fFP0sN5ZL0BPG4bAvv7PkOpf4zMXR+w= In-Reply-To: Content-Language: en-US List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Roman Gushchin , Waiman Long Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Muchun Song , Alex Shi , Chris Down , Yafang Shao , Wei Yang , Masayoshi Mizuma , Xing Zhengjun On 4/22/21 9:56 PM, Roman Gushchin wrote: > On Thu, Apr 22, 2021 at 12:58:52PM -0400, Waiman Long wrote: >> On 4/21/21 7:28 PM, Roman Gushchin wrote: >>> On Tue, Apr 20, 2021 at 03:29:05PM -0400, Waiman Long wrote: >>>> Before the new slab memory controller with per object byte charging, >>>> charging and vmstat data update happen only when new slab pages are >>>> allocated or freed. Now they are done with every kmem_cache_alloc() >>>> and kmem_cache_free(). This causes additional overhead for workloads >>>> that generate a lot of alloc and free calls. >>>> >>>> The memcg_stock_pcp is used to cache byte charge for a specific >>>> obj_cgroup to reduce that overhead. To further reducing it, this patch >>>> makes the vmstat data cached in the memcg_stock_pcp structure as well >>>> until it accumulates a page size worth of update or when other cached >>>> data change. Caching the vmstat data in the per-cpu stock eliminates two >>>> writes to non-hot cachelines for memcg specific as well as memcg-lruvecs >>>> specific vmstat data by a write to a hot local stock cacheline. >>>> >>>> On a 2-socket Cascade Lake server with instrumentation enabled and this >>>> patch applied, it was found that about 20% (634400 out of 3243830) >>>> of the time when mod_objcg_state() is called leads to an actual call >>>> to __mod_objcg_state() after initial boot. When doing parallel kernel >>>> build, the figure was about 17% (24329265 out of 142512465). So caching >>>> the vmstat data reduces the number of calls to __mod_objcg_state() >>>> by more than 80%. >>>> >>>> Signed-off-by: Waiman Long >>>> Reviewed-by: Shakeel Butt >>>> --- >>>> mm/memcontrol.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++-- >>>> 1 file changed, 83 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>> index 7cd7187a017c..292b4783b1a7 100644 >>>> --- a/mm/memcontrol.c >>>> +++ b/mm/memcontrol.c >>>> @@ -782,8 +782,9 @@ void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val) >>>> rcu_read_unlock(); >>>> } >>>> -void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, >>>> - enum node_stat_item idx, int nr) >>>> +static inline void mod_objcg_mlstate(struct obj_cgroup *objcg, >>>> + struct pglist_data *pgdat, >>>> + enum node_stat_item idx, int nr) >>>> { >>>> struct mem_cgroup *memcg; >>>> struct lruvec *lruvec; >>>> @@ -791,7 +792,7 @@ void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, >>>> rcu_read_lock(); >>>> memcg = obj_cgroup_memcg(objcg); >>>> lruvec = mem_cgroup_lruvec(memcg, pgdat); >>>> - mod_memcg_lruvec_state(lruvec, idx, nr); >>>> + __mod_memcg_lruvec_state(lruvec, idx, nr); >>>> rcu_read_unlock(); >>>> } >>>> @@ -2059,7 +2060,10 @@ struct memcg_stock_pcp { >>>> #ifdef CONFIG_MEMCG_KMEM >>>> struct obj_cgroup *cached_objcg; >>>> + struct pglist_data *cached_pgdat; >>> I wonder if we want to have per-node counters instead? >>> That would complicate the initialization of pcp stocks a bit, >>> but might shave off some additional cpu time. >>> But we can do it later too. >>> >> A per node counter will certainly complicate the code and reduce the >> performance benefit too. > Hm, why? We wouldn't need to flush the stock if the release happens > on some other cpu not matching the current pgdat. I had actually experimented with just caching vmstat data for the local node only. It turned out the hit rate was a bit lower. That is why I keep the current approach and I need to do further investigation on a better approach. Cheers, Longman