From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4519EC433DB for ; Thu, 28 Jan 2021 13:45:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 92F7B64DD9 for ; Thu, 28 Jan 2021 13:45:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 92F7B64DD9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BF3B56B0073; Thu, 28 Jan 2021 08:45:05 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B7B616B0074; Thu, 28 Jan 2021 08:45:05 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A446F6B0083; Thu, 28 Jan 2021 08:45:05 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0070.hostedemail.com [216.40.44.70]) by kanga.kvack.org (Postfix) with ESMTP id 878356B0073 for ; Thu, 28 Jan 2021 08:45:05 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 3A66B181AEF3C for ; Thu, 28 Jan 2021 13:45:05 +0000 (UTC) X-FDA: 77755304970.19.juice88_6108333275a0 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin19.hostedemail.com (Postfix) with ESMTP id 155B61ACEA2 for ; Thu, 28 Jan 2021 13:45:05 +0000 (UTC) X-HE-Tag: juice88_6108333275a0 X-Filterd-Recvd-Size: 5853 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Jan 2021 13:45:04 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5F976ACB7; Thu, 28 Jan 2021 13:45:02 +0000 (UTC) Date: Thu, 28 Jan 2021 14:44:58 +0100 From: Oscar Salvador To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Thomas Gleixner , "Peter Zijlstra (Intel)" , Mike Rapoport , Michal Hocko , Wei Yang Subject: Re: [PATCH v1 2/2] mm/page_alloc: count CMA pages per zone and print them in /proc/zoneinfo Message-ID: <20210128134458.GA8136@localhost.localdomain> References: <20210127101813.6370-1-david@redhat.com> <20210127101813.6370-3-david@redhat.com> <20210128102234.GB5250@localhost.localdomain> <2246d657-4f6d-c27d-4ae2-853a8437cda9@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2246d657-4f6d-c27d-4ae2-853a8437cda9@redhat.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 28, 2021 at 11:43:41AM +0100, David Hildenbrand wrote: > > My knowledge of CMA tends to be quite low, actually I though that CMA > > was somehow tied to ZONE_MOVABLE. > > CMA is often placed into one of the kernel zones, but can also end up in the movable zone. Ok good to know. > > I see how tracking CMA pages per zona might give you a clue, but what do > > you mean by "might behave differently - even after some of these pages might > > already have been allocated" > > Assume you have 4GB in ZONE_NORMAL but 1GB is assigned for CMA. You actually only have 3GB available for random kernel allocations, not 4GB. > > Currently, you can only observe the free CMA pages, excluding any pages that are already allocated. Having that information how many CMA pages we have can be helpful - similar to what we already have in /proc/meminfo. I see, I agree that it can provide some guidance. > > I see that NR_FREE_CMA_PAGES is there even without CONFIG_CMA, as you > > said, but I am not sure about adding size to a zone unconditionally. > > I mean, it is not terrible as IIRC, the maximum MAX_NUMNODES can get > > is 1024, and on x86_64 that would be (1024 * 4 zones) * 8 = 32K. > > So not a big deal, but still. > > I'm asking myself how many such systems will run without > CONFIG_CMA in the future. I am not sure, my comment was just to point out that even the added size might not be that large, hiding it under CONFIG_CMA seemed the right thing to do. > > diff --git a/mm/vmstat.c b/mm/vmstat.c > > index 8ba0870ecddd..5757df4bfd45 100644 > > --- a/mm/vmstat.c > > +++ b/mm/vmstat.c > > @@ -1559,13 +1559,15 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat, > > "\n spanned %lu" > > "\n present %lu" > > "\n managed %lu", > > + "\n cma %lu", > > zone_page_state(zone, NR_FREE_PAGES), > > min_wmark_pages(zone), > > low_wmark_pages(zone), > > high_wmark_pages(zone), > > zone->spanned_pages, > > zone->present_pages, > > - zone->managed_pages); > > + zone->managed_pages, > > + IS_ENABLED(CONFIG_CMA) ? zone->cma_pages : 0); > > seq_printf(m, > > "\n protection: (%ld", > > > > > > I do not see it that ugly, but just my taste. > > IIRC, that does not work. The compiler will still complain > about a missing struct members. We would have to provide a > zone_cma_pages() helper with some ifdefery. Of course, it seems I switched off my brain. > We could do something like this on top > > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -530,7 +530,9 @@ struct zone { > atomic_long_t managed_pages; > unsigned long spanned_pages; > unsigned long present_pages; > +#ifdef CONFIG_CMA > unsigned long cma_pages; > +#endif > const char *name; > diff --git a/mm/vmstat.c b/mm/vmstat.c > index 97fc32a53320..b753a64f099f 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -1643,7 +1643,10 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat, > "\n spanned %lu" > "\n present %lu" > "\n managed %lu" > - "\n cma %lu", > +#ifdef CONFIG_CMA > + "\n cma %lu" > +#endif > + "%s", > zone_page_state(zone, NR_FREE_PAGES), > min_wmark_pages(zone), > low_wmark_pages(zone), > @@ -1651,7 +1654,10 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat, > zone->spanned_pages, > zone->present_pages, > zone_managed_pages(zone), > - zone->cma_pages); > +#ifdef CONFIG_CMA > + zone->cma_pages, > +#endif > + ""); > seq_printf(m, > "\n protection: (%ld", Looks good to me, but I can see how those #ifdef can raise some eyebrows. Let us see what other thinks as well. Btw, should linux-uapi be CCed, as /proc/vmstat layout will change? -- Oscar Salvador SUSE L3