From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Mike Rapoport <rppt@kernel.org>, Michal Hocko <mhocko@kernel.org>,
Wei Yang <richard.weiyang@linux.alibaba.com>
Subject: Re: [PATCH v1 2/2] mm/page_alloc: count CMA pages per zone and print them in /proc/zoneinfo
Date: Thu, 28 Jan 2021 11:22:34 +0100 [thread overview]
Message-ID: <20210128102234.GB5250@localhost.localdomain> (raw)
In-Reply-To: <20210127101813.6370-3-david@redhat.com>
On Wed, Jan 27, 2021 at 11:18:13AM +0100, David Hildenbrand wrote:
> Let's count the number of CMA pages per zone and print them in
> /proc/zoneinfo.
>
> Having access to the total number of CMA pages per zone is helpful for
> debugging purposes to know where exactly the CMA pages ended up, and to
> figure out how many pages of a zone might behave differently (e.g., like
> ZONE_MOVABLE) - even after some of these pages might already have been
> allocated.
My knowledge of CMA tends to be quite low, actually I though that CMA
was somehow tied to ZONE_MOVABLE.
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"
> For now, we are only able to get the global nr+free cma pages from
> /proc/meminfo and the free cma pages per zone from /proc/zoneinfo.
>
> Note: Track/print that information even without CONFIG_CMA, similar to
> "nr_free_cma" in /proc/zoneinfo. This is different to /proc/meminfo -
> maybe we want to make that consistent in the future (however, changing
> /proc/zoneinfo output might uglify the code a bit).
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> include/linux/mmzone.h | 4 ++++
> mm/page_alloc.c | 1 +
> mm/vmstat.c | 6 ++++--
> 3 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index ae588b2f87ef..3bc18c9976fd 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -503,6 +503,9 @@ struct zone {
> * bootmem allocator):
> * managed_pages = present_pages - reserved_pages;
> *
> + * cma pages is present pages that are assigned for CMA use
> + * (MIGRATE_CMA).
> + *
> * So present_pages may be used by memory hotplug or memory power
> * management logic to figure out unmanaged pages by checking
> * (present_pages - managed_pages). And managed_pages should be used
> @@ -527,6 +530,7 @@ struct zone {
> atomic_long_t managed_pages;
> unsigned long spanned_pages;
> unsigned long present_pages;
> + unsigned long cma_pages;
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.
Besides following NR_FREE_CMA_PAGES, is there any reason for not doing:
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 1e22d96734e0..2d8a830d168d 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -436,6 +436,9 @@ struct zone {
unsigned long 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 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.
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-01-28 10:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 10:18 [PATCH v1 0/2] mm/cma: better error handling and count pages per zone David Hildenbrand
2021-01-27 10:18 ` [PATCH v1 1/2] mm/cma: expose all pages to the buddy if activation of an area fails David Hildenbrand
2021-01-27 15:58 ` Zi Yan
2021-01-28 9:59 ` Oscar Salvador
2021-01-27 10:18 ` [PATCH v1 2/2] mm/page_alloc: count CMA pages per zone and print them in /proc/zoneinfo David Hildenbrand
2021-01-28 10:22 ` Oscar Salvador [this message]
2021-01-28 10:43 ` David Hildenbrand
2021-01-28 13:44 ` Oscar Salvador
2021-01-28 13:46 ` Oscar Salvador
2021-01-28 14:01 ` David Hildenbrand
2021-01-28 16:45 ` [PATCH v2] " David Hildenbrand
2021-01-28 21:42 ` Oscar Salvador
2021-01-28 21:54 ` David Rientjes
2021-01-28 22:03 ` David Hildenbrand
2021-01-28 22:28 ` David Rientjes
2021-01-28 22:30 ` David Hildenbrand
2021-01-29 11:34 ` [PATCH v3] " David Hildenbrand
2021-01-29 11:46 ` Oscar Salvador
2021-01-29 11:51 ` David Hildenbrand
2021-01-30 8:48 ` David Rientjes
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