From: Uladzislau Rezki <urezki@gmail.com>
To: Baoquan He <bhe@redhat.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>,
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 18:53:45 +0200 [thread overview]
Message-ID: <ZP9GGW/q0nCFelLf@pc636> (raw)
In-Reply-To: <ZP59pbh9SKROtjlr@MiWiFi-R3L-srv>
On Mon, Sep 11, 2023 at 10:38:29AM +0800, Baoquan He wrote:
> 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.
>
I am OK to add "vmap_" prefix:
vmap_nodes;
vmap_nr_nodes;
vmap_node_size;
..
If you are not OK with that, feel free to propose other variants.
Thank you!
--
Uladzislau Rezki
next prev parent reply other threads:[~2023-09-11 16:53 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
2023-09-11 16:53 ` Uladzislau Rezki [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZP9GGW/q0nCFelLf@pc636 \
--to=urezki@gmail.com \
--cc=Liam.Howlett@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=bhe@redhat.com \
--cc=david@fromorbit.com \
--cc=hch@infradead.org \
--cc=joel@joelfernandes.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lstoakes@gmail.com \
--cc=oleksiy.avramchenko@sony.com \
--cc=paulmck@kernel.org \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).