Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753095AbeAJXAf (ORCPT + 1 other); Wed, 10 Jan 2018 18:00:35 -0500 Received: from mail-pg0-f67.google.com ([74.125.83.67]:43558 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752443AbeAJXAe (ORCPT ); Wed, 10 Jan 2018 18:00:34 -0500 X-Google-Smtp-Source: ACJfBotdFAarNJqkd9TYYAoaKaAZaqQr1onqlDHcyApFctKqrBLfsQsqkI//Df0GxzUgQeaxFIBb+g== Date: Wed, 10 Jan 2018 15:00:30 -0800 From: Yu Zhao To: Dan Streetman , Seth Jennings Cc: Sergey Senozhatsky , Minchan Kim , Nitin Gupta , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] zswap: only save zswap header when necessary Message-ID: <20180110230030.GA110374@google.com> References: <20180108225101.15790-1-yuzhao@google.com> <20180110224741.83751-1-yuzhao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180110224741.83751-1-yuzhao@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Wed, Jan 10, 2018 at 02:47:41PM -0800, Yu Zhao wrote: > We waste sizeof(swp_entry_t) for zswap header when using zsmalloc > as zpool driver because zsmalloc doesn't support eviction. > > Add zpool_evictable() to detect if zpool is potentially evictable, > and use it in zswap to avoid waste memory for zswap header. > > Signed-off-by: Yu Zhao > --- > include/linux/zpool.h | 2 ++ > mm/zpool.c | 26 ++++++++++++++++++++++++-- > mm/zsmalloc.c | 7 ------- > mm/zswap.c | 20 ++++++++++---------- > 4 files changed, 36 insertions(+), 19 deletions(-) > > diff --git a/include/linux/zpool.h b/include/linux/zpool.h > index 004ba807df96..7238865e75b0 100644 > --- a/include/linux/zpool.h > +++ b/include/linux/zpool.h > @@ -108,4 +108,6 @@ void zpool_register_driver(struct zpool_driver *driver); > > int zpool_unregister_driver(struct zpool_driver *driver); > > +bool zpool_evictable(struct zpool *pool); > + > #endif > diff --git a/mm/zpool.c b/mm/zpool.c > index fd3ff719c32c..ec63ef32d73d 100644 > --- a/mm/zpool.c > +++ b/mm/zpool.c > @@ -21,6 +21,7 @@ struct zpool { > struct zpool_driver *driver; > void *pool; > const struct zpool_ops *ops; > + bool evictable; > > struct list_head list; > }; > @@ -142,7 +143,7 @@ EXPORT_SYMBOL(zpool_has_pool); > * > * This creates a new zpool of the specified type. The gfp flags will be > * used when allocating memory, if the implementation supports it. If the > - * ops param is NULL, then the created zpool will not be shrinkable. > + * ops param is NULL, then the created zpool will not be evictable. > * > * Implementations must guarantee this to be thread-safe. > * > @@ -180,6 +181,8 @@ struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp, > zpool->driver = driver; > zpool->pool = driver->create(name, gfp, ops, zpool); > zpool->ops = ops; > + zpool->evictable = zpool->driver->shrink && > + zpool->ops && zpool->ops->evict; The zpool->" prefix is a result out copy & paste. Fixed in the next version. Sorry for the spam.