From: Jisheng Zhang <jszhang@marvell.com>
To: <davem@davemloft.net>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Weird NET_RX softirq behavior
Date: Thu, 7 Aug 2014 17:10:50 +0800 [thread overview]
Message-ID: <20140807171050.77819b10@xhacker> (raw)
Hi list,
I observed one weird NET_RX softirq behavior:
1. CONFIG_RPS=y in kernel config file.
2. only one netdev in the system: eth0. eth0 only has one interrupt which is
all handled by CPU0. eth0 doesn't support RFS_ACCEL
"cat /proc/interrupts" shows
~ # cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3
...
49: 52 0 0 0 GIC mmc1
52: 53 0 0 0 GIC mmc2
56: 430365 0 0 0 GIC eth0
60: 61 0 0 0 GIC mmc0
...
3. RPS and RFS remains disabled as default.
~ # ls /sys/class/net/eth0/queues/
rx-0 rx-1 rx-2 rx-3 tx-0
~ # cat /sys/class/net/eth0/queues/rx-*/rps_cpus
0
0
0
0
~ # cat /proc/sys/net/core/rps_sock_flow_entries
0
~ # cat /sys/class/net/eth0/queues/rx-*/rps_flow_cnt
0
0
0
0
4. But NET_RX seems abnormal
~ # cat /proc/softirqs
CPU0 CPU1 CPU2 CPU3
HI: 0 0 0 0
TIMER: 92386 767 367 263
NET_TX: 6338 0 0 1
NET_RX: 445587 322 983 0
BLOCK: 0 0 0 0
BLOCK_IOPOLL: 0 0 0 0
TASKLET: 150 0 0 0
SCHED: 31414 490 275 179
HRTIMER: 1 0 0 0
RCU: 49029 570 285 182
I'm expecting NET_RX under CPU1, 2, 3 should be zero. Any suggestions
about this abnormal behavior?
Thanks in advance,
Jisheng
next reply other threads:[~2014-08-07 9:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-07 9:10 Jisheng Zhang [this message]
2014-08-07 14:18 ` Weird NET_RX softirq behavior Dmitry Popov
2014-08-08 2:37 ` Jisheng Zhang
2014-08-08 5:47 ` Eric Dumazet
2014-08-08 6:55 ` Jisheng Zhang
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