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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94FDDC433FE for ; Fri, 18 Nov 2022 19:24:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B58576B0071; Fri, 18 Nov 2022 14:24:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B08416B0072; Fri, 18 Nov 2022 14:24:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9CFDC8E0001; Fri, 18 Nov 2022 14:24:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 8E5BA6B0071 for ; Fri, 18 Nov 2022 14:24:18 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 50A03AAF33 for ; Fri, 18 Nov 2022 19:24:18 +0000 (UTC) X-FDA: 80147538996.01.5A9D1FD Received: from mail-pf1-f177.google.com (mail-pf1-f177.google.com [209.85.210.177]) by imf05.hostedemail.com (Postfix) with ESMTP id E63CF100008 for ; Fri, 18 Nov 2022 19:24:16 +0000 (UTC) Received: by mail-pf1-f177.google.com with SMTP id b185so5776953pfb.9 for ; Fri, 18 Nov 2022 11:24:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=mdCngp0163ZOC7R4UmapaO07RFseynPajyc/BjnA5YY=; b=XT4lmqMuxy3rDFluUzTnDbQxEYFF7FbgM07BgL4VhzVaTzKKmVo+PDV4EcTmnRINYR +8rq5TxSXwBSGjnXmKzBBJFRBya0zSS9UvA5nCbTNaqLWHGtVs+uJ+6KtmORseROIUGQ B1gpDbr/ozmrjJ7JdrAVKRqVAtOJKN2vGeRVi2i/HiReNlTDdnW4JwmczynZam6iFkvS l5GG+QS27WCGItZ9NeeHqCB7Yw6A4UzklWHdUQKLaSqgqWCUwrAs0FnffHL5GB3zdTfl 1zxnswIisIkryuQXC22qcvESiu35fkIu+iOMlU3HkZj3FyIjfURti8HhaUA1aC8IjvJ1 cuyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=mdCngp0163ZOC7R4UmapaO07RFseynPajyc/BjnA5YY=; b=kdLRP+S5o+Da8oB+Fs6DEv3nhuv/fbmiquc7/oyULNCC45CcDNPehkQFaAGJcj+frK XpwAgLsKmFKBfB7ind0BCjIySBNaMJR6fPpGhmix/upMlzjXj7wdu2isBcuzPZAZVddz CbG7An6j3HGuQdn2/YbgjvWPoDerUcG7Tq8muFvjS4pPbqnlMdbTfrCrLyBz+gcHsznT noPB/4G+VSGxDq5M6De5G7xFgR/VKM9GGynldcjyhk18r5cIGmgDhB+RR7TGhkNYJR2Q MfDnQzSvS10dLv5SwZ1/SFUWPwnTH8qI0mOVAj/SMu0BCNkjcwKOGQhsqtmENJ3k7YnO elig== X-Gm-Message-State: ANoB5pkQs/JTXSKHIWyNFMxRC+FRiOIBixpAJYrF65bZZ5+K5BdLefnT rkhKdXSwx2Qy/9A5Q7qHuiY= X-Google-Smtp-Source: AA0mqf4YXL5oNrj/5Fz4qpcvyXB/rghSqMveqidcZO95YJiKisNyQ7OZ8TV2mAFd2ngWGl1wdhDLtg== X-Received: by 2002:a05:6a00:2908:b0:56b:d738:9b with SMTP id cg8-20020a056a00290800b0056bd738009bmr9214469pfb.61.1668799455580; Fri, 18 Nov 2022 11:24:15 -0800 (PST) Received: from google.com ([2620:15c:211:201:bba9:9f92:b2cc:16a4]) by smtp.gmail.com with ESMTPSA id p1-20020a170902e74100b00186b280a441sm4108482plf.239.2022.11.18.11.24.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Nov 2022 11:24:15 -0800 (PST) Date: Fri, 18 Nov 2022 11:24:13 -0800 From: Minchan Kim To: Johannes Weiner Cc: Nhat Pham , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ngupta@vflare.org, senozhatsky@chromium.org, sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com Subject: Re: [PATCH v4 3/5] zsmalloc: Add a LRU to zs_pool to keep track of zspages in LRU order Message-ID: References: <20221117163839.230900-1-nphamcs@gmail.com> <20221117163839.230900-4-nphamcs@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668799457; a=rsa-sha256; cv=none; b=xuW22v/AmEYz1786ykA1zm4YeShkaEJyI3Y2+WVPoJLDA4s5Jwsh/g0nnaXpPBdHZCkD2f G8WLZ8miTsloQFW2uYphHMHAy9k6H/bAyK0ocgfsVbPtGfT/TLTWyQW18YpIY6B4BSmK/y wqNRAGUlJ7k8JkjbxRwL6sHX8HKqrzc= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=XT4lmqMu; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=pass (imf05.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.210.177 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668799457; h=from:from:sender:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=mdCngp0163ZOC7R4UmapaO07RFseynPajyc/BjnA5YY=; b=lOnr7K1gY4g9DWs4s6B+iOmz8oDwNVBQjRKXli7D2tkyL4MaWg90SW0GJmIaVox3BkEbSF GJX7l71eH3Kg/Yl0vxGIqWBFiwM+6y9Lurmf8EOQDekWKpE/y3hRZw/BCeHX4Pdn+BymIV CR5wtNYIz549+j5tgfJnQBapz5XJ4yw= Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=XT4lmqMu; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=pass (imf05.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.210.177 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com X-Rspam-User: X-Stat-Signature: ibx6p815mkx9p95cbm9kgkigxrtfbxfr X-Rspamd-Queue-Id: E63CF100008 X-Rspamd-Server: rspam11 X-HE-Tag: 1668799456-909026 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 Thu, Nov 17, 2022 at 11:30:11PM -0500, Johannes Weiner wrote: > On Thu, Nov 17, 2022 at 02:15:11PM -0800, Minchan Kim wrote: > > On Thu, Nov 17, 2022 at 08:38:37AM -0800, Nhat Pham wrote: > > > This helps determines the coldest zspages as candidates for writeback. > > > > > > Signed-off-by: Nhat Pham > > > --- > > > mm/zsmalloc.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > > > 1 file changed, 46 insertions(+) > > > > > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > > > index 326faa751f0a..2557b55ec767 100644 > > > --- a/mm/zsmalloc.c > > > +++ b/mm/zsmalloc.c > > > @@ -239,6 +239,11 @@ struct zs_pool { > > > /* Compact classes */ > > > struct shrinker shrinker; > > > > > > +#ifdef CONFIG_ZPOOL > > > + /* List tracking the zspages in LRU order by most recently added object */ > > > + struct list_head lru; > > > +#endif > > > + > > > #ifdef CONFIG_ZSMALLOC_STAT > > > struct dentry *stat_dentry; > > > #endif > > > @@ -260,6 +265,12 @@ struct zspage { > > > unsigned int freeobj; > > > struct page *first_page; > > > struct list_head list; /* fullness list */ > > > + > > > +#ifdef CONFIG_ZPOOL > > > + /* links the zspage to the lru list in the pool */ > > > + struct list_head lru; > > > +#endif > > > + > > > struct zs_pool *pool; > > > #ifdef CONFIG_COMPACTION > > > rwlock_t lock; > > > @@ -352,6 +363,18 @@ static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage) > > > kmem_cache_free(pool->zspage_cachep, zspage); > > > } > > > > > > +#ifdef CONFIG_ZPOOL > > > +/* Moves the zspage to the front of the zspool's LRU */ > > > +static void move_to_front(struct zs_pool *pool, struct zspage *zspage) > > > +{ > > > + assert_spin_locked(&pool->lock); > > > + > > > + if (!list_empty(&zspage->lru)) > > > + list_del(&zspage->lru); > > > + list_add(&zspage->lru, &pool->lru); > > > +} > > > +#endif > > > + > > > /* pool->lock(which owns the handle) synchronizes races */ > > > static void record_obj(unsigned long handle, unsigned long obj) > > > { > > > @@ -953,6 +976,9 @@ static void free_zspage(struct zs_pool *pool, struct size_class *class, > > > } > > > > > > remove_zspage(class, zspage, ZS_EMPTY); > > > +#ifdef CONFIG_ZPOOL > > > + list_del(&zspage->lru); > > > +#endif > > > __free_zspage(pool, class, zspage); > > > } > > > > > > @@ -998,6 +1024,10 @@ static void init_zspage(struct size_class *class, struct zspage *zspage) > > > off %= PAGE_SIZE; > > > } > > > > > > +#ifdef CONFIG_ZPOOL > > > + INIT_LIST_HEAD(&zspage->lru); > > > +#endif > > > + > > > set_freeobj(zspage, 0); > > > } > > > > > > @@ -1418,6 +1448,11 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp) > > > fix_fullness_group(class, zspage); > > > record_obj(handle, obj); > > > class_stat_inc(class, OBJ_USED, 1); > > > + > > > +#ifdef CONFIG_ZPOOL > > > + /* Move the zspage to front of pool's LRU */ > > > + move_to_front(pool, zspage); > > > +#endif > > > spin_unlock(&pool->lock); > > > > > > return handle; > > > @@ -1444,6 +1479,10 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp) > > > > > > /* We completely set up zspage so mark them as movable */ > > > SetZsPageMovable(pool, zspage); > > > +#ifdef CONFIG_ZPOOL > > > + /* Move the zspage to front of pool's LRU */ > > > + move_to_front(pool, zspage); > > > +#endif > > > spin_unlock(&pool->lock); > > > > Why do we move the zspage in the alloc instead of accessor? > > > > Isn't zs_map_object better place since it's clear semantic > > that user start to access the object? > > Remember that this is used for swap, and these entries aren't accessed > on an ongoing basis while in the pool. An access means swapin. So > functionally this is fine. > > On cleaner choices, I would actually agree with you that map would be > more appropriate. But all I can do is repeat replies from previous > questions: We're not reinventing the wheel here. zbud and z3fold do it > this way, and this follows their precedent. We've talked about wanting > to generalize the LRU, and that's a heck of a lot easier if we have > copies of *one* implementation that we can deduplicate - instead of > having to merge multiple implementations with arbitrary differences. It's already very weird to add the LRU logic into allocator but since you have talked that you are working general LRU concept what I preferred and this temporal work would be beneficial to get all the requirements for the work, I wanted to help this as interim solution since I know the general LRU is bigger work than this. However, If you also agree the suggestion(adding LRU into mapping function rather than allocation) and it doesn't change any behavior, why not? If the divergence would make harder for your upcoming LRU work, I totally agree with you but I don't see such one line change makes your duduplication work harder. At the same time, I am trying to make zsmalloc *reasonable* rather than "Yeah, I am fine to take something smelly code since others are already doing it" stance. > > So as you review these patches, please compare what they do to zbud > and z3fold. Those existing zpool implementations have been a common > answer in response to review questions. I did and thought it's weird and the correction is trivial.