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Fri, 18 Nov 2022 11:32:03 -0800 (PST) Received: from google.com ([2620:15c:211:201:bba9:9f92:b2cc:16a4]) by smtp.gmail.com with ESMTPSA id cp17-20020a170902e79100b00186b8752a78sm4080558plb.80.2022.11.18.11.32.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Nov 2022 11:32:03 -0800 (PST) Sender: Minchan Kim Date: Fri, 18 Nov 2022 11:32:01 -0800 From: Minchan Kim To: Nhat Pham Cc: akpm@linux-foundation.org, hannes@cmpxchg.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 v5 4/6] zsmalloc: Add a LRU to zs_pool to keep track of zspages in LRU order Message-ID: References: <20221118182407.82548-1-nphamcs@gmail.com> <20221118182407.82548-5-nphamcs@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221118182407.82548-5-nphamcs@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 18, 2022 at 10:24:05AM -0800, Nhat Pham wrote: > This helps determines the coldest zspages as candidates for writeback. > > Signed-off-by: Nhat Pham > --- > mm/zsmalloc.c | 45 +++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 43 insertions(+), 2 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index 326faa751f0a..9e7b54324181 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); > } > > @@ -1418,9 +1448,8 @@ 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); > - spin_unlock(&pool->lock); > > - return handle; > + goto out; > } > > spin_unlock(&pool->lock); > @@ -1444,6 +1473,11 @@ 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); > +out: > +#ifdef CONFIG_ZPOOL > + /* Move the zspage to front of pool's LRU */ > + move_to_front(pool, zspage); > +#endif > spin_unlock(&pool->lock); Please move the move_to_front into zs_map_object with ZS_MM_WO with comment with "why we are doing only for WO case".