Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757221AbbFBJZp (ORCPT ); Tue, 2 Jun 2015 05:25:45 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53567 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752249AbbFBJZh (ORCPT ); Tue, 2 Jun 2015 05:25:37 -0400 Date: Tue, 2 Jun 2015 11:25:35 +0200 From: Michal Hocko To: Vlastimil Babka Cc: Mel Gorman , Johannes Weiner , Andrew Morton , Naoya Horiguchi , linux-mm@kvack.org, LKML Subject: Re: [PATCH] hugetlb: Do not account hugetlb pages as NR_FILE_PAGES Message-ID: <20150602092535.GB4440@dhcp22.suse.cz> References: <1432214842-22730-1-git-send-email-mhocko@suse.cz> <20150521170909.GA12800@cmpxchg.org> <20150522142143.GF5109@dhcp22.suse.cz> <20150522143558.GA2462@suse.de> <55633EAC.8060702@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55633EAC.8060702@suse.cz> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2732 Lines: 83 On Mon 25-05-15 17:24:28, Vlastimil Babka wrote: > On 05/22/2015 04:35 PM, Mel Gorman wrote: > >> > >> Thanks! > >> > >> > This makes a lot of sense to me. The only thing I worry about is the > >> > proliferation of PageHuge(), a function call, in relatively hot paths. > >> > >> I've tried that (see the patch below) but it enlarged the code by almost > >> 1k > >> text data bss dec hex filename > >> 510323 74273 44440 629036 9992c mm/built-in.o.before > >> 511248 74273 44440 629961 99cc9 mm/built-in.o.after > >> > >> I am not sure the code size increase is worth it. Maybe we can reduce > >> the check to only PageCompound(page) as huge pages are no in the page > >> cache (yet). > >> > > > > That would be a more sensible route because it also avoids exposing the > > hugetlbfs destructor unnecessarily. > > You could maybe do test such as (PageCompound(page) && PageHuge(page)) to > short-circuit the call while remaining future-proof. How about this? --- diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 91b7f9b2b774..bb8a70e8fc77 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -547,7 +547,13 @@ static inline void ClearPageCompound(struct page *page) #endif /* !PAGEFLAGS_EXTENDED */ #ifdef CONFIG_HUGETLB_PAGE -int PageHuge(struct page *page); +int __PageHuge(struct page *page); +static inline int PageHuge(struct page *page) +{ + if (!PageCompound(page)) + return 0; + return __PageHuge(page); +} int PageHeadHuge(struct page *page); bool page_huge_active(struct page *page); #else diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 33defbe1897f..648c0c32857c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1107,19 +1107,17 @@ static void prep_compound_gigantic_page(struct page *page, unsigned long order) } /* - * PageHuge() only returns true for hugetlbfs pages, but not for normal or + * __PageHuge() only returns true for hugetlbfs pages, but not for normal or * transparent huge pages. See the PageTransHuge() documentation for more * details. */ -int PageHuge(struct page *page) +int __PageHuge(struct page *page) { - if (!PageCompound(page)) - return 0; - + VM_BUG_ON(!PageCompound(page)); page = compound_head(page); return get_compound_page_dtor(page) == free_huge_page; } -EXPORT_SYMBOL_GPL(PageHuge); +EXPORT_SYMBOL_GPL(__PageHuge); /* * PageHeadHuge() only returns true for hugetlbfs head page, but not for -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/