netdev - [PATCH v2 net-next 2/5] net-smnp: reorganize SNMP fast path variables

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Message-ID: <20231017014716.3944813-3-lixiaoyan@google.com>
Date: Tue, 17 Oct 2023 01:47:13 +0000
From: Coco Li <lixiaoyan@...gle.com>
To: Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com>, 
	Neal Cardwell <ncardwell@...gle.com>, Mubashir Adnan Qureshi <mubashirq@...gle.com>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, Chao Wu <wwchao@...gle.com>, Wei Wang <weiwan@...gle.com>, 
	Coco Li <lixiaoyan@...gle.com>, David Ahern <dsahern@...nel.org>
Subject: [PATCH v2 net-next 2/5] net-smnp: reorganize SNMP fast path variables

From: Chao Wu <wwchao@...gle.com>

Reorganize fast path variables on tx-txrx-rx order.
Fast path cacheline ends afer LINUX_MIB_DELAYEDACKLOCKED.
There are only read-write variables here.

Below data generated with pahole on x86 architecture.

Fast path variables span cache lines before change: 12
Fast path variables span cache lines after change: 2

Signed-off-by: Chao Wu <wwchao@...gle.com>
Signed-off-by: Coco Li <lixiaoyan@...gle.com>
Suggested-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: David Ahern <dsahern@...nel.org>
---
 include/uapi/linux/snmp.h | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 26f33a4c253d7..aefb39edb87c6 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -169,7 +169,28 @@ enum
 /* linux mib definitions */
 enum
 {
+	/* Caacheline organization can be found documented in
+	 * Documentation/networking/net_cachelines/snmp.rst.
+	 * Please update the document when adding new fields.
+	 */
+
 	LINUX_MIB_NUM = 0,
+	/* TX hotpath */
+	LINUX_MIB_TCPAUTOCORKING,		/* TCPAutoCorking */
+	LINUX_MIB_TCPFROMZEROWINDOWADV,		/* TCPFromZeroWindowAdv */
+	LINUX_MIB_TCPTOZEROWINDOWADV,		/* TCPToZeroWindowAdv */
+	LINUX_MIB_TCPWANTZEROWINDOWADV,		/* TCPWantZeroWindowAdv */
+	LINUX_MIB_TCPORIGDATASENT,		/* TCPOrigDataSent */
+	LINUX_MIB_TCPPUREACKS,			/* TCPPureAcks */
+	LINUX_MIB_TCPHPACKS,			/* TCPHPAcks */
+	LINUX_MIB_TCPDELIVERED,			/* TCPDelivered */
+	/* RX hotpath */
+	LINUX_MIB_TCPHPHITS,			/* TCPHPHits */
+	LINUX_MIB_TCPRCVCOALESCE,		/* TCPRcvCoalesce */
+	LINUX_MIB_TCPKEEPALIVE,			/* TCPKeepAlive */
+	LINUX_MIB_DELAYEDACKS,			/* DelayedACKs */
+	LINUX_MIB_DELAYEDACKLOCKED,		/* DelayedACKLocked */
+	/* End of hotpath variables */
 	LINUX_MIB_SYNCOOKIESSENT,		/* SyncookiesSent */
 	LINUX_MIB_SYNCOOKIESRECV,		/* SyncookiesRecv */
 	LINUX_MIB_SYNCOOKIESFAILED,		/* SyncookiesFailed */
@@ -185,14 +206,9 @@ enum
 	LINUX_MIB_TIMEWAITKILLED,		/* TimeWaitKilled */
 	LINUX_MIB_PAWSACTIVEREJECTED,		/* PAWSActiveRejected */
 	LINUX_MIB_PAWSESTABREJECTED,		/* PAWSEstabRejected */
-	LINUX_MIB_DELAYEDACKS,			/* DelayedACKs */
-	LINUX_MIB_DELAYEDACKLOCKED,		/* DelayedACKLocked */
 	LINUX_MIB_DELAYEDACKLOST,		/* DelayedACKLost */
 	LINUX_MIB_LISTENOVERFLOWS,		/* ListenOverflows */
 	LINUX_MIB_LISTENDROPS,			/* ListenDrops */
-	LINUX_MIB_TCPHPHITS,			/* TCPHPHits */
-	LINUX_MIB_TCPPUREACKS,			/* TCPPureAcks */
-	LINUX_MIB_TCPHPACKS,			/* TCPHPAcks */
 	LINUX_MIB_TCPRENORECOVERY,		/* TCPRenoRecovery */
 	LINUX_MIB_TCPSACKRECOVERY,		/* TCPSackRecovery */
 	LINUX_MIB_TCPSACKRENEGING,		/* TCPSACKReneging */
@@ -246,7 +262,6 @@ enum
 	LINUX_MIB_TCPREQQFULLDOCOOKIES,		/* TCPReqQFullDoCookies */
 	LINUX_MIB_TCPREQQFULLDROP,		/* TCPReqQFullDrop */
 	LINUX_MIB_TCPRETRANSFAIL,		/* TCPRetransFail */
-	LINUX_MIB_TCPRCVCOALESCE,		/* TCPRcvCoalesce */
 	LINUX_MIB_TCPBACKLOGCOALESCE,		/* TCPBacklogCoalesce */
 	LINUX_MIB_TCPOFOQUEUE,			/* TCPOFOQueue */
 	LINUX_MIB_TCPOFODROP,			/* TCPOFODrop */
@@ -262,12 +277,7 @@ enum
 	LINUX_MIB_TCPFASTOPENBLACKHOLE,		/* TCPFastOpenBlackholeDetect */
 	LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES, /* TCPSpuriousRtxHostQueues */
 	LINUX_MIB_BUSYPOLLRXPACKETS,		/* BusyPollRxPackets */
-	LINUX_MIB_TCPAUTOCORKING,		/* TCPAutoCorking */
-	LINUX_MIB_TCPFROMZEROWINDOWADV,		/* TCPFromZeroWindowAdv */
-	LINUX_MIB_TCPTOZEROWINDOWADV,		/* TCPToZeroWindowAdv */
-	LINUX_MIB_TCPWANTZEROWINDOWADV,		/* TCPWantZeroWindowAdv */
 	LINUX_MIB_TCPSYNRETRANS,		/* TCPSynRetrans */
-	LINUX_MIB_TCPORIGDATASENT,		/* TCPOrigDataSent */
 	LINUX_MIB_TCPHYSTARTTRAINDETECT,	/* TCPHystartTrainDetect */
 	LINUX_MIB_TCPHYSTARTTRAINCWND,		/* TCPHystartTrainCwnd */
 	LINUX_MIB_TCPHYSTARTDELAYDETECT,	/* TCPHystartDelayDetect */
@@ -279,10 +289,8 @@ enum
 	LINUX_MIB_TCPACKSKIPPEDTIMEWAIT,	/* TCPACKSkippedTimeWait */
 	LINUX_MIB_TCPACKSKIPPEDCHALLENGE,	/* TCPACKSkippedChallenge */
 	LINUX_MIB_TCPWINPROBE,			/* TCPWinProbe */
-	LINUX_MIB_TCPKEEPALIVE,			/* TCPKeepAlive */
 	LINUX_MIB_TCPMTUPFAIL,			/* TCPMTUPFail */
 	LINUX_MIB_TCPMTUPSUCCESS,		/* TCPMTUPSuccess */
-	LINUX_MIB_TCPDELIVERED,			/* TCPDelivered */
 	LINUX_MIB_TCPDELIVEREDCE,		/* TCPDeliveredCE */
 	LINUX_MIB_TCPACKCOMPRESSED,		/* TCPAckCompressed */
 	LINUX_MIB_TCPZEROWINDOWDROP,		/* TCPZeroWindowDrop */
-- 
2.42.0.655.g421f12c284-goog