From: Xu Kuohai <xukuohai@huawei.com>
To: <bpf@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>
Subject: [PATCH bpf-next v4] bpf: Initialize same number of free nodes for each pcpu_freelist
Date: Thu, 10 Nov 2022 07:21:28 -0500 [thread overview]
Message-ID: <20221110122128.105214-1-xukuohai@huawei.com> (raw)
pcpu_freelist_populate() initializes nr_elems / num_possible_cpus() + 1
free nodes for some CPUs, and then possibly one CPU with fewer nodes,
followed by remaining cpus with 0 nodes. For example, when nr_elems == 256
and num_possible_cpus() == 32, CPU 0~27 each gets 9 free nodes, CPU 28 gets
4 free nodes, CPU 29~31 get 0 free nodes, while in fact each CPU should get
8 nodes equally.
This patch initializes nr_elems / num_possible_cpus() free nodes for each
CPU firstly, then allocates the remaining free nodes by one for each CPU
until no free nodes left.
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
v4: Remove unneeded min()
v3: Simplify code as suggested by Andrii
v2: Update commit message and add Yonghong's ack
---
kernel/bpf/percpu_freelist.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c
index b6e7f5c5b9ab..27f2c4aff623 100644
--- a/kernel/bpf/percpu_freelist.c
+++ b/kernel/bpf/percpu_freelist.c
@@ -100,22 +100,22 @@ void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size,
u32 nr_elems)
{
struct pcpu_freelist_head *head;
- int i, cpu, pcpu_entries;
+ unsigned int cpu, cpu_idx, i, j, n, m;
- pcpu_entries = nr_elems / num_possible_cpus() + 1;
- i = 0;
+ n = nr_elems / num_possible_cpus();
+ m = nr_elems % num_possible_cpus();
+
+ cpu_idx = 0;
for_each_possible_cpu(cpu) {
-again:
- head = per_cpu_ptr(s->freelist, cpu);
- /* No locking required as this is not visible yet. */
- pcpu_freelist_push_node(head, buf);
- i++;
- buf += elem_size;
- if (i == nr_elems)
- break;
- if (i % pcpu_entries)
- goto again;
+ j = n + (cpu_idx < m ? 1 : 0);
+ for (i = 0; i < j; i++) {
+ head = per_cpu_ptr(s->freelist, cpu);
+ /* No locking required as this is not visible yet. */
+ pcpu_freelist_push_node(head, buf);
+ buf += elem_size;
+ }
+ cpu_idx++;
}
}
--
2.30.2
next reply other threads:[~2022-11-10 12:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-10 12:21 Xu Kuohai [this message]
2022-11-11 3:53 ` [PATCH bpf-next v4] bpf: Initialize same number of free nodes for each pcpu_freelist wuqiang
2022-11-11 7:00 ` Xu Kuohai
2022-11-11 20:12 ` Andrii Nakryiko
2022-11-12 3:48 ` Xu Kuohai
2022-11-11 20:20 ` patchwork-bot+netdevbpf
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=20221110122128.105214-1-xukuohai@huawei.com \
--to=xukuohai@huawei.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=haoluo@google.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kpsingh@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.lau@linux.dev \
--cc=sdf@google.com \
--cc=song@kernel.org \
--cc=yhs@fb.com \
/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).