From: Roman Gushchin <guro@fb.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>, <linux-api@vger.kernel.org>,
Michal Hocko <mhocko@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Christoph Lameter <cl@linux.com>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Mel Gorman <mgorman@techsingularity.net>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v3 2/7] mm, slab/slub: introduce kmalloc-reclaimable caches
Date: Thu, 19 Jul 2018 11:16:17 -0700 [thread overview]
Message-ID: <20180719181613.GA26595@castle.DHCP.thefacebook.com> (raw)
In-Reply-To: <20180718133620.6205-3-vbabka@suse.cz>
On Wed, Jul 18, 2018 at 03:36:15PM +0200, Vlastimil Babka wrote:
> Kmem caches can be created with a SLAB_RECLAIM_ACCOUNT flag, which indicates
> they contain objects which can be reclaimed under memory pressure (typically
> through a shrinker). This makes the slab pages accounted as NR_SLAB_RECLAIMABLE
> in vmstat, which is reflected also the MemAvailable meminfo counter and in
> overcommit decisions. The slab pages are also allocated with __GFP_RECLAIMABLE,
> which is good for anti-fragmentation through grouping pages by mobility.
>
> The generic kmalloc-X caches are created without this flag, but sometimes are
> used also for objects that can be reclaimed, which due to varying size cannot
> have a dedicated kmem cache with SLAB_RECLAIM_ACCOUNT flag. A prominent example
> are dcache external names, which prompted the creation of a new, manually
> managed vmstat counter NR_INDIRECTLY_RECLAIMABLE_BYTES in commit f1782c9bc547
> ("dcache: account external names as indirectly reclaimable memory").
>
> To better handle this and any other similar cases, this patch introduces
> SLAB_RECLAIM_ACCOUNT variants of kmalloc caches, named kmalloc-rcl-X.
> They are used whenever the kmalloc() call passes __GFP_RECLAIMABLE among gfp
> flags. They are added to the kmalloc_caches array as a new type. Allocations
> with both __GFP_DMA and __GFP_RECLAIMABLE will use a dma type cache.
>
> This change only applies to SLAB and SLUB, not SLOB. This is fine, since SLOB's
> target are tiny system and this patch does add some overhead of kmem management
> objects.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> include/linux/slab.h | 16 +++++++++++----
> mm/slab_common.c | 48 ++++++++++++++++++++++++++++----------------
> 2 files changed, 43 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 4299c59353a1..d89e934e0d8b 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -296,11 +296,12 @@ static inline void __check_heap_object(const void *ptr, unsigned long n,
> (KMALLOC_MIN_SIZE) : 16)
>
> #define KMALLOC_NORMAL 0
> +#define KMALLOC_RECLAIM 1
> #ifdef CONFIG_ZONE_DMA
> -#define KMALLOC_DMA 1
> -#define KMALLOC_TYPES 2
> +#define KMALLOC_DMA 2
> +#define KMALLOC_TYPES 3
> #else
> -#define KMALLOC_TYPES 1
> +#define KMALLOC_TYPES 2
> #endif
>
> #ifndef CONFIG_SLOB
> @@ -309,12 +310,19 @@ extern struct kmem_cache *kmalloc_caches[KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
> static __always_inline unsigned int kmalloc_type(gfp_t flags)
> {
> int is_dma = 0;
> + int is_reclaimable;
>
> #ifdef CONFIG_ZONE_DMA
> is_dma = !!(flags & __GFP_DMA);
> #endif
>
> - return is_dma;
> + is_reclaimable = !!(flags & __GFP_RECLAIMABLE);
> +
> + /*
> + * If an allocation is botth __GFP_DMA and __GFP_RECLAIMABLE, return
^^
typo
> + * KMALLOC_DMA and effectively ignore __GFP_RECLAIMABLE
> + */
> + return (is_dma * 2) + (is_reclaimable & !is_dma);
Maybe
is_dma * KMALLOC_DMA + (is_reclaimable && !is_dma) * KMALLOC_RECLAIM
looks better?
> }
>
> /*
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 4614248ca381..614fb7ab8312 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1107,10 +1107,21 @@ void __init setup_kmalloc_cache_index_table(void)
> }
> }
>
> -static void __init new_kmalloc_cache(int idx, slab_flags_t flags)
> +static void __init
> +new_kmalloc_cache(int idx, int type, slab_flags_t flags)
> {
> - kmalloc_caches[KMALLOC_NORMAL][idx] = create_kmalloc_cache(
> - kmalloc_info[idx].name,
> + const char *name;
> +
> + if (type == KMALLOC_RECLAIM) {
> + flags |= SLAB_RECLAIM_ACCOUNT;
> + name = kasprintf(GFP_NOWAIT, "kmalloc-rcl-%u",
> + kmalloc_info[idx].size);
> + BUG_ON(!name);
I'd replace this with WARN_ON() and falling back to kmalloc_info[idx].name.
> + } else {
> + name = kmalloc_info[idx].name;
> + }
> +
> + kmalloc_caches[type][idx] = create_kmalloc_cache(name,
> kmalloc_info[idx].size, flags, 0,
> kmalloc_info[idx].size);
> }
next prev parent reply other threads:[~2018-07-19 18:17 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-18 13:36 [PATCH v3 0/7] kmalloc-reclaimable caches Vlastimil Babka
2018-07-18 13:36 ` [PATCH v3 1/7] mm, slab: combine kmalloc_caches and kmalloc_dma_caches Vlastimil Babka
2018-07-19 8:10 ` Mel Gorman
2018-07-20 9:30 ` Vlastimil Babka
2018-07-30 15:38 ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 2/7] mm, slab/slub: introduce kmalloc-reclaimable caches Vlastimil Babka
2018-07-19 8:23 ` Mel Gorman
2018-07-20 9:32 ` Vlastimil Babka
2018-07-19 18:16 ` Roman Gushchin [this message]
2018-07-20 9:35 ` Vlastimil Babka
2018-07-30 15:41 ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 3/7] mm, slab: allocate off-slab freelists as reclaimable when appropriate Vlastimil Babka
2018-07-19 8:35 ` Mel Gorman
2018-07-20 9:37 ` Vlastimil Babka
2018-07-30 15:45 ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 4/7] dcache: allocate external names from reclaimable kmalloc caches Vlastimil Babka
2018-07-19 8:42 ` Mel Gorman
2018-07-18 13:36 ` [PATCH v3 5/7] mm: rename and change semantics of nr_indirectly_reclaimable_bytes Vlastimil Babka
2018-07-30 15:46 ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 6/7] mm, proc: add KReclaimable to /proc/meminfo Vlastimil Babka
2018-07-18 13:36 ` [PATCH v3 7/7] mm, slab: shorten kmalloc cache names for large sizes Vlastimil Babka
2018-07-19 8:46 ` Mel Gorman
2018-07-30 15:48 ` Christopher Lameter
2018-07-31 8:55 ` Vlastimil Babka
2018-07-19 19:53 ` [PATCH v3 0/7] kmalloc-reclaimable caches Roman Gushchin
2018-07-20 9:45 ` Vlastimil Babka
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