From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx193.postini.com [74.125.245.193]) by kanga.kvack.org (Postfix) with SMTP id 4729C6B0037 for ; Sat, 16 Mar 2013 09:03:10 -0400 (EDT) Received: by mail-ve0-f178.google.com with SMTP id db10so3318886veb.9 for ; Sat, 16 Mar 2013 06:03:09 -0700 (PDT) Date: Sat, 16 Mar 2013 09:03:04 -0400 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH v2 1/4] introduce zero filled pages handler Message-ID: <20130316130302.GA5987@konrad-lan.dumpdata.com> References: <1363255697-19674-1-git-send-email-liwanp@linux.vnet.ibm.com> <1363255697-19674-2-git-send-email-liwanp@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1363255697-19674-2-git-send-email-liwanp@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wanpeng Li Cc: Greg Kroah-Hartman , Andrew Morton , Dan Magenheimer , Seth Jennings , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Mar 14, 2013 at 06:08:14PM +0800, Wanpeng Li wrote: > Introduce zero-filled pages handler to capture and handle zero pages. > > Acked-by: Dan Magenheimer > Signed-off-by: Wanpeng Li > --- > drivers/staging/zcache/zcache-main.c | 26 ++++++++++++++++++++++++++ > 1 files changed, 26 insertions(+), 0 deletions(-) > > diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c > index 328898e..b71e033 100644 > --- a/drivers/staging/zcache/zcache-main.c > +++ b/drivers/staging/zcache/zcache-main.c > @@ -460,6 +460,32 @@ static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool) > kmem_cache_free(zcache_obj_cache, obj); > } > > +static bool page_zero_filled(void *ptr) Shouldn't this be 'struct page *p' ? > +{ > + unsigned int pos; > + unsigned long *page; > + > + page = (unsigned long *)ptr; That way you can avoid this casting. > + > + for (pos = 0; pos < PAGE_SIZE / sizeof(*page); pos++) { > + if (page[pos]) > + return false; Perhaps allocate a static page filled with zeros and just do memcmp? > + } > + > + return true; > +} > + > +static void handle_zero_page(void *page) > +{ > + void *user_mem; > + > + user_mem = kmap_atomic(page); > + memset(user_mem, 0, PAGE_SIZE); > + kunmap_atomic(user_mem); > + > + flush_dcache_page(page); This is new. Could you kindly explain why it is needed? Thanks. > +} > + > static struct tmem_hostops zcache_hostops = { > .obj_alloc = zcache_obj_alloc, > .obj_free = zcache_obj_free, > -- > 1.7.7.6 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org