From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seth Jennings Subject: Re: [PATCH 03/10] zsmalloc: always update lru ordering of each zspage Date: Thu, 11 Sep 2014 22:20:32 -0500 Message-ID: <20140912032032.GC17818@cerebellum.variantweb.net> References: <1410468841-320-1-git-send-email-ddstreet@ieee.org> <1410468841-320-4-git-send-email-ddstreet@ieee.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1410468841-320-4-git-send-email-ddstreet@ieee.org> Sender: linux-kernel-owner@vger.kernel.org To: Dan Streetman Cc: Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Nitin Gupta , Andrew Morton List-Id: linux-mm.kvack.org On Thu, Sep 11, 2014 at 04:53:54PM -0400, Dan Streetman wrote: > Update ordering of a changed zspage in its fullness group LRU list, > even if it has not moved to a different fullness group. > > This is needed by zsmalloc shrinking, which partially relies on each > class fullness group list to be kept in LRU order, so the oldest can > be reclaimed first. Currently, LRU ordering is only updated when > a zspage changes fullness groups. Just something I saw. fix_fullness_group() is called from zs_free(), which means that removing an object from a zspage moves it to the front of the LRU. Not sure if that is what we want. If anything that makes it a _better_ candidate for reclaim as the zspage is now contains fewer objects that we'll have to decompress and writeback. Seth > > Signed-off-by: Dan Streetman > Cc: Minchan Kim > --- > mm/zsmalloc.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index fedb70f..51db622 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -467,16 +467,14 @@ static enum fullness_group fix_fullness_group(struct zs_pool *pool, > BUG_ON(!is_first_page(page)); > > get_zspage_mapping(page, &class_idx, &currfg); > - newfg = get_fullness_group(page); > - if (newfg == currfg) > - goto out; > - > class = &pool->size_class[class_idx]; > + newfg = get_fullness_group(page); > + /* Need to do this even if currfg == newfg, to update lru */ > remove_zspage(page, class, currfg); > insert_zspage(page, class, newfg); > - set_zspage_mapping(page, class_idx, newfg); > + if (currfg != newfg) > + set_zspage_mapping(page, class_idx, newfg); > > -out: > return newfg; > } > > -- > 1.8.3.1 >