From: Baoquan He <bhe@redhat.com>
To: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
Dave Chinner <david@fromorbit.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Subject: Re: [PATCH v2 4/9] mm: vmalloc: Remove global vmap_area_root rb-tree
Date: Mon, 11 Sep 2023 10:38:29 +0800 [thread overview]
Message-ID: <ZP59pbh9SKROtjlr@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20230829081142.3619-5-urezki@gmail.com>
On 08/29/23 at 10:11am, Uladzislau Rezki (Sony) wrote:
> Store allocated objects in a separate nodes. A va->va_start
> address is converted into a correct node where it should
> be placed and resided. An addr_to_node() function is used
> to do a proper address conversion to determine a node that
> contains a VA.
>
> Such approach balances VAs across nodes as a result an access
> becomes scalable. Number of nodes in a system depends on number
> of CPUs divided by two. The density factor in this case is 1/2.
>
> Please note:
>
> 1. As of now allocated VAs are bound to a node-0. It means the
> patch does not give any difference comparing with a current
> behavior;
>
> 2. The global vmap_area_lock, vmap_area_root are removed as there
> is no need in it anymore. The vmap_area_list is still kept and
> is _empty_. It is exported for a kexec only;
>
> 3. The vmallocinfo and vread() have to be reworked to be able to
> handle multiple nodes.
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
> mm/vmalloc.c | 209 +++++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 161 insertions(+), 48 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index b7deacca1483..ae0368c314ff 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -728,11 +728,9 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
> #define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0
>
>
> -static DEFINE_SPINLOCK(vmap_area_lock);
> static DEFINE_SPINLOCK(free_vmap_area_lock);
> /* Export for kexec only */
> LIST_HEAD(vmap_area_list);
> -static struct rb_root vmap_area_root = RB_ROOT;
> static bool vmap_initialized __read_mostly;
>
> static struct rb_root purge_vmap_area_root = RB_ROOT;
> @@ -772,6 +770,38 @@ static struct rb_root free_vmap_area_root = RB_ROOT;
> */
> static DEFINE_PER_CPU(struct vmap_area *, ne_fit_preload_node);
>
> +/*
> + * An effective vmap-node logic. Users make use of nodes instead
> + * of a global heap. It allows to balance an access and mitigate
> + * contention.
> + */
> +struct rb_list {
> + struct rb_root root;
> + struct list_head head;
> + spinlock_t lock;
> +};
> +
> +struct vmap_node {
> + /* Bookkeeping data of this node. */
> + struct rb_list busy;
> +};
> +
> +static struct vmap_node *nodes, snode;
> +static __read_mostly unsigned int nr_nodes = 1;
> +static __read_mostly unsigned int node_size = 1;
It could be better if calling these global variables a meaningful name,
e.g vmap_nodes, static_vmap_nodes, nr_vmap_nodes. When I use vim+cscope
to reference them, it gives me a super long list. Aside from that, a
simple name often makes me mistake it as a local virable. A weak
opinion.
> +
> +static inline unsigned int
> +addr_to_node_id(unsigned long addr)
> +{
> + return (addr / node_size) % nr_nodes;
> +}
> +
> +static inline struct vmap_node *
> +addr_to_node(unsigned long addr)
> +{
> + return &nodes[addr_to_node_id(addr)];
> +}
> +
> static __always_inline unsigned long
> va_size(struct vmap_area *va)
> {
next prev parent reply other threads:[~2023-09-11 2:38 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-29 8:11 [PATCH v2 0/9] Mitigate a vmap lock contention v2 Uladzislau Rezki (Sony)
2023-08-29 8:11 ` [PATCH v2 1/9] mm: vmalloc: Add va_alloc() helper Uladzislau Rezki (Sony)
2023-09-06 5:51 ` Baoquan He
2023-09-06 15:06 ` Uladzislau Rezki
2023-08-29 8:11 ` [PATCH v2 2/9] mm: vmalloc: Rename adjust_va_to_fit_type() function Uladzislau Rezki (Sony)
2023-09-06 5:51 ` Baoquan He
2023-09-06 16:27 ` Uladzislau Rezki
2023-08-29 8:11 ` [PATCH v2 3/9] mm: vmalloc: Move vmap_init_free_space() down in vmalloc.c Uladzislau Rezki (Sony)
2023-09-06 5:52 ` Baoquan He
2023-09-06 16:29 ` Uladzislau Rezki
2023-08-29 8:11 ` [PATCH v2 4/9] mm: vmalloc: Remove global vmap_area_root rb-tree Uladzislau Rezki (Sony)
2023-08-29 14:30 ` kernel test robot
2023-08-30 14:48 ` Uladzislau Rezki
2023-09-07 2:17 ` Baoquan He
2023-09-07 9:38 ` Baoquan He
2023-09-07 9:40 ` Uladzislau Rezki
2023-09-07 9:39 ` Uladzislau Rezki
2023-09-07 9:58 ` Baoquan He
2023-09-08 1:51 ` HAGIO KAZUHITO(萩尾 一仁)
2023-09-08 4:43 ` Baoquan He
2023-09-08 5:01 ` HAGIO KAZUHITO(萩尾 一仁)
2023-09-08 6:44 ` Baoquan He
2023-09-08 11:25 ` Uladzislau Rezki
2023-09-08 11:38 ` Baoquan He
2023-09-08 13:23 ` Uladzislau Rezki
2023-09-11 2:38 ` Baoquan He [this message]
2023-09-11 16:53 ` Uladzislau Rezki
2023-09-12 13:19 ` Baoquan He
2023-08-29 8:11 ` [PATCH v2 5/9] mm: vmalloc: Remove global purge_vmap_area_root rb-tree Uladzislau Rezki (Sony)
2023-09-11 2:57 ` Baoquan He
2023-09-11 17:00 ` Uladzislau Rezki
2023-08-29 8:11 ` [PATCH v2 6/9] mm: vmalloc: Offload free_vmap_area_lock lock Uladzislau Rezki (Sony)
2023-09-06 6:04 ` Baoquan He
2023-09-06 19:16 ` Uladzislau Rezki
2023-09-07 0:06 ` Baoquan He
2023-09-07 9:33 ` Uladzislau Rezki
2023-09-11 3:25 ` Baoquan He
2023-09-11 17:10 ` Uladzislau Rezki
2023-09-12 13:21 ` Baoquan He
2023-08-29 8:11 ` [PATCH v2 7/9] mm: vmalloc: Support multiple nodes in vread_iter Uladzislau Rezki (Sony)
2023-09-11 3:58 ` Baoquan He
2023-09-11 18:16 ` Uladzislau Rezki
2023-09-12 13:42 ` Baoquan He
2023-09-13 15:42 ` Uladzislau Rezki
2023-09-14 3:02 ` Baoquan He
2023-09-14 3:36 ` Baoquan He
2023-09-14 3:38 ` Baoquan He
2023-09-13 10:59 ` Baoquan He
2023-09-13 15:38 ` Uladzislau Rezki
2023-08-29 8:11 ` [PATCH v2 8/9] mm: vmalloc: Support multiple nodes in vmallocinfo Uladzislau Rezki (Sony)
2023-09-15 13:02 ` Baoquan He
2023-09-15 18:32 ` Uladzislau Rezki
2023-08-29 8:11 ` [PATCH v2 9/9] mm: vmalloc: Set nr_nodes/node_size based on CPU-cores Uladzislau Rezki (Sony)
2023-09-15 13:03 ` Baoquan He
2023-09-15 18:31 ` Uladzislau Rezki
2023-08-31 1:15 ` [PATCH v2 0/9] Mitigate a vmap lock contention v2 Baoquan He
2023-08-31 16:26 ` Uladzislau Rezki
2023-09-04 14:55 ` Uladzislau Rezki
2023-09-04 19:53 ` Andrew Morton
2023-09-05 6:53 ` Uladzislau Rezki
2023-09-06 20:04 ` Lorenzo Stoakes
2023-09-07 9:15 ` Uladzislau Rezki
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