From: Shaokun Zhang <zhangshaokun@hisilicon.com>
To: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: Yuqi Jin <jinyuqi@huawei.com>,
"David S. Miller" <davem@davemloft.net>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Eric Dumazet <edumazet@google.com>,
Yang Guo <guoyang2@huawei.com>,
Shaokun Zhang <zhangshaokun@hisilicon.com>
Subject: [PATCH] net: optimize cmpxchg in ip_idents_reserve
Date: Wed, 15 Jan 2020 11:23:40 +0800 [thread overview]
Message-ID: <1579058620-26684-1-git-send-email-zhangshaokun@hisilicon.com> (raw)
From: Yuqi Jin <jinyuqi@huawei.com>
atomic_try_cmpxchg is called instead of atomic_cmpxchg that can reduce
the access number of the global variable @p_id in the loop. Let's
optimize it for performance.
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Yang Guo <guoyang2@huawei.com>
Signed-off-by: Yuqi Jin <jinyuqi@huawei.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
---
net/ipv4/route.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 87e979f2b74a..7e28c7121c20 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -496,10 +496,10 @@ u32 ip_idents_reserve(u32 hash, int segs)
delta = prandom_u32_max(now - old);
/* Do not use atomic_add_return() as it makes UBSAN unhappy */
+ old = (u32)atomic_read(p_id);
do {
- old = (u32)atomic_read(p_id);
new = old + delta + segs;
- } while (atomic_cmpxchg(p_id, old, new) != old);
+ } while (!atomic_try_cmpxchg(p_id, &old, new));
return new - segs;
}
--
2.7.4
next reply other threads:[~2020-01-15 3:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 3:23 Shaokun Zhang [this message]
2020-01-16 12:27 ` [PATCH] net: optimize cmpxchg in ip_idents_reserve David Miller
2020-01-16 14:05 ` Shaokun Zhang
2020-01-16 15:12 ` Eric Dumazet
2020-01-16 15:19 ` Eric Dumazet
2020-01-17 6:54 ` Shaokun Zhang
2020-01-17 12:32 ` Peter Zijlstra
2020-01-17 16:35 ` Eric Dumazet
2020-01-17 18:03 ` Arvind Sankar
2020-01-17 18:16 ` Eric Dumazet
2020-01-17 18:38 ` Arvind Sankar
2020-01-17 18:48 ` Eric Dumazet
2020-01-20 8:18 ` Peter Zijlstra
2020-05-07 9:12 ` Shaokun Zhang
2020-05-07 13:49 ` Eric Dumazet
2020-01-19 3:46 ` Shaokun Zhang
2020-01-19 4:12 ` Eric Dumazet
2020-01-21 2:40 ` Shaokun Zhang
2020-01-22 8:49 ` Peter Zijlstra
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=1579058620-26684-1-git-send-email-zhangshaokun@hisilicon.com \
--to=zhangshaokun@hisilicon.com \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=guoyang2@huawei.com \
--cc=jinyuqi@huawei.com \
--cc=kuznet@ms2.inr.ac.ru \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=yoshfuji@linux-ipv6.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).