Hi, Kumar, 1) Regarding rx queues: what does "ls /sys/class/net/eth0/queues" show ? 2) can you try setting affinity for working only with CPU3 and see what happens after some traffic is sent by cat /proc/interrupts? regards, Rami Rosen http://ramirose.wix.com/ramirosen On Tue, Mar 26, 2013 at 8:31 PM, Kumar amit mehta <gmate.amit@xxxxxxxxx> wrote: > Hi All, > > I was reading some stuff on interrupts and irq lines today and I thought I'll > expermient with the network rx path. To start with, I've a Virtual Machine > running 3.8 linux kernel. My machine has 4 CPU cores, network (eth) interface > is driven by pcnet_32 AMD driver and is tied to IRQ line #19. I started some > network traffic and I notice that out of those 4 CPUs, only one of them is being > used and despite changing the CPU affinity, I still don't see the other cores > being used for this network traffic. So based on this behavior(please see the > logs below), I've these following queries: > i) Does it mean that this network card do not have multiple Rx Queues ? > ii) I think all the modern NICs must be implementing multiple Rx Queues and > hence Can someone please point me to the simplest of such implemenation in any > of the in-tree drivers ? > iii) I'm just doing a simple 'ping' to google with of big size packets, As I do > not have a peer to use packetgen/netperf/iperf utilities. > > ref: Comments in double quotes. > <logs> > $ uname -r > 3.8.0-rc6-next-20130208 > > $ cat /proc/cpuinfo |grep processor > processor : 0 > processor : 1 > processor : 2 > processor : 3 > "Total 4 cpu cores" > > $ cat /proc/interrupts|egrep 'eth0|CPU' > CPU0 CPU1 CPU2 CPU3 > 19: 5103 74 33 5 IO-APIC-fasteoi eth0 > "IRQ Line #19 for the network device" > > $ lspci|grep -i ethernet > 02:01.0 Ethernet controller: Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE] > (rev 10) > > "AMD NIC" > $ lspci -s 02:01.0 -vvv|grep module > Kernel modules: pcnet32 > > $ lsmod|grep pcnet32 > pcnet32 40671 0 > "driver" > > # whoami > root > > # cat /proc/irq/19/smp_affinity > 03 > > # cat /proc/irq/19/affinity_hint > 00 > > "I think smp_affinity is a bit map, therefore for all the four cores to be > utilized, all 4 bits should be set to 1, which leads to 15(0xf), hence Chaning > the cpu affinity" > # echo 15 > /proc/irq/19/smp_affinity > # cat /proc/irq/19/smp_affinity > 15 > > "started network traffic here and monitoring it" > # cat /proc/interrupts|grep eth0 > 19: 5452 78 33 5 IO-APIC-fasteoi eth0 > # cat /proc/interrupts|grep eth0 > 19: 5488 78 35 5 IO-APIC-fasteoi eth0 > # cat /proc/interrupts|grep eth0 > 19: 5492 78 35 5 IO-APIC-fasteoi eth0 > # cat /proc/interrupts|grep eth0 > 19: 5500 78 35 5 IO-APIC-fasteoi eth0 > ................................. > .........after some time......... > # cat /proc/interrupts|grep eth0 > 19: 6035 78 42 5 IO-APIC-fasteoi eth0 > > "Most of the packets are still getting routed through CPU0 *Only*." > <logs> > > -Amit > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
