netdev - [PATCH net-next] net: align pcpu_sw_netstats and pcpu

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Message-Id: <20181116152424.222826-1-edumazet@google.com>
Date:   Fri, 16 Nov 2018 07:24:24 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next] net: align pcpu_sw_netstats and pcpu_lstats structs

Do not risk spanning these small structures on two cache lines,
it is absolutely not worth it.

For 32bit arches, the hint might not be enough, but we do not
really care anymore.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/linux/netdevice.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 917ae7b6263e4686ac7af4d16445f4e996001ea6..086e64d885971ff04f186d488975b3305a0fbb1d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2389,13 +2389,13 @@ struct pcpu_sw_netstats {
 	u64     tx_packets;
 	u64     tx_bytes;
 	struct u64_stats_sync   syncp;
-};
+} __aligned(4 * sizeof(u64));
 
 struct pcpu_lstats {
 	u64 packets;
 	u64 bytes;
 	struct u64_stats_sync syncp;
-};
+} __aligned(2 * sizeof(u64));
 
 #define __netdev_alloc_pcpu_stats(type, gfp)				\
 ({									\
-- 
2.19.1.1215.g8438c0b245-goog