It differs for each driver. Generally, for intel drivers, the driver version says whether its NAPI-mode or not. We can know this by command "modinfo e1000 |grep NAPI" . Or else, 'ethtool -i <interface name>' (where interface-name, should be intel-device interface-name like: eth0 or eth1..). Where as for Broadcom, the driver version, doesn't say, whether its NAPI-mode or not. I don’t' know how to identify this for Broadcom? Regards, Madhukar. -----Original Message----- From: yong xue [mailto:ultraice@xxxxxxxxx] Sent: Wednesday, October 15, 2008 9:09 PM To: Mythri, Madhukar [NETPWR/EMBED/HYDE] Cc: porterde@xxxxxxxxxxxxx; linux-net@xxxxxxxxxxxxxxx Subject: Re: e1000 softirq load balancing with a running system, can you please tell me that how to check what the driver model is, NAPI or interrupt? 2008/10/15, Madhukar.Mythri@xxxxxxxxxxx <Madhukar.Mythri@xxxxxxxxxxx>: > > First make-sure whether you have one dedicated interrupt-line for each > network card. > You got 100% CPU utilization with NAPI Disabled or Enabled ? > > With NAPI enabled, and assign each interrupt-line to each CPU. And > check whether the interrupts are distributed as per you assigned, by > seeing "cat /proc/interrupts" and by pumping traffic. > And also check how the interrupts balanced between CPU's. > > As per my observation, when NAPI enabled, the interrupt-line cannot > assign to each CPU. In NAPI-mode for whichever the CPU got the first > interrupt, that CPU only carried out in poll-mode for rest of the > loaded packets(H/W buffers). > > So, with NAPI enabled, if interrupts are not distributed on assigned > CPU's and one CPU got loaded more, then try by Disabling NAPI, and use > 'irqbalance' utility to load-balance the interrupts between all CPU's. > (http://www.irqbalance.org/). > > Regards, > Madhukar. > > -----Original Message----- > From: Don Porter [mailto:porterde@xxxxxxxxxxxxx] > Sent: Wednesday, October 15, 2008 6:23 PM > To: Mythri, Madhukar [NETPWR/EMBED/HYDE] > Cc: linux-net@xxxxxxxxxxxxxxx > Subject: Re: e1000 softirq load balancing > > I believe I have 4 interrupt lines, but I will have to double-check. > > I have successfully used /proc/irq/####/smp_affinity to assign the > interrupts to 4 different CPUs. The problem is in the softirq portion > of the interrupt handling, where CPU usage indicates that they are all > being funneled back to a single CPU. > > Does that make sense? I feel like one ought to be able to have 4 > softirq daemons servicing incoming packets, not just one. > > Thanks, > Don > > Madhukar.Mythri@xxxxxxxxxxx wrote: > > You are saying that, 4 Intel 82571EB Gb NICs (2 pci cards x 2 > > NICs/chip) using the e1000 driver. > > So, do you have 4 interrupt lines or only 2-lines? > > > > Based on this, if you have 4 interrupt lines, then you can assign > > each > > > interrupt-line to each CPU-core, with NAPI enabled(for good > > performance). > > > > Regards, > > Madhukar. > > -----Original Message----- > > From: linux-net-owner@xxxxxxxxxxxxxxx > > [mailto:linux-net-owner@xxxxxxxxxxxxxxx] On Behalf Of Don Porter > > Sent: Wednesday, October 15, 2008 12:36 AM > > To: linux-net@xxxxxxxxxxxxxxx > > Subject: e1000 softirq load balancing > > > > Hi, > > > > Background: > > > > I have a 16 core x86_64 machine (4 chips x 4 cores/chip) that has 4 > > Intel 82571EB Gb NICs (2 pci cards x 2 NICs/chip) using the e1000 > > driver. > > > > I have a simple client/server micro-benchmark that pounds a server > > on each NIC with requests to measure peak throughput. I am running > > Ubuntu 8.04.1, kernel version 2.6.24. > > > > Problem: > > > > What I am observing is that a single ksoftirqd thread is becoming a > > bottleneck for the system. > > More specifically, one cpu runs ksoftirqd at 100% cpu utilization, > > while > > 4 cpus each run their servers at about 25%. I carefully used > > sched_setaffinity() to map server threads to cpus and > > /proc/irq/<device>/smp_affinity to map hardware interrupts to cpus > > such that there should be exactly 1 cpu per server thread and 1 cpu > > for servicing hardware interrupts per device. > > > > I can observe (via /proc/interrupts) that the interrupts are being > > distributed properly, but despite this I only see 1 or 2 ksoftirqd > > running, and the server daemons bottlenecked behind them. (This is > > with NAPI disabled. With NAPI enabled, I can't get even 2 ksoftirqd > > threads to run). I have tried varous permutations such as assigning > > each hardware interrupt to a different physical chip. > > > > Desired Result: > > > > It seems to me that with 4 independent NICs and plenty of CPUs to > > spare, I ought to be able to assign one softirq daemon to each NIC > > rather than funnelling all of the traffic through 1 or 2. > > > > Any advice on this issue is greatly appreciated. > > > > Best regards, > > Don Porter > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-net" > > in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo > > info at http://vger.kernel.org/majordomo-info.html > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-net" > in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo > info at http://vger.kernel.org/majordomo-info.html > -- Best Regards, 薛 勇 QQ:312200 e-mail:ultraice@xxxxxxxxx MSN:it@xxxxxxxxxxxxxxxxx ��.n��������+%������w��{.n�����{��w��)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
