On Thu, Sep 3, 2015 at 12:06 PM, Jintack Lim <jint...@cs.columbia.edu> wrote:
> Hi, > > I was trying to set irq affinity by writing a value > to /proc/irq/<irq>/smp_affinity, > but smp_affinity value was not changed at all. > Ian suggested to take this to the devel list. > I'm working on Xen4.5, ARMv8. > I checked that setting smp_affinity works on Xen4.5, x86. So, probably this is an ARM specific issue. > > Thanks, > Jintack > > On Thu, Sep 3, 2015 at 11:34 AM, Ian Campbell <ian.campb...@citrix.com> > wrote: > >> On Thu, 2015-09-03 at 10:59 -0400, Jintack Lim wrote: >> > Hi, >> > >> > While I was running Apache server, >> > I found that one of Dom0 vcpu is running 100% to handle irqs, >> > and those irqs are set to be processed only on that specific vcpu. >> > >> > Referring to this document, >> > http://wiki.xen.org/wiki/Network_Throughput_and_Performance_Guide >> > I tried to change smp_affinity by writing a value to /proc/irq/<irq >> > -no>/smp_affinity, >> > however the smp_affinity value was not changed. >> > >> > I'm working on Xen 4.5 on ARMv8, >> > and the irq is netback tx interrupt. >> > >> > # cat /proc/irq/106/smp_affinity >> > 1 >> > >> > # cat /proc/interrupts >> > ... >> > 106: 53849 0 0 0 xen-dyn-event >> > vif1.1-q0-tx >> > 107: 1 0 0 0 xen-dyn-event >> > vif1.1-q0-rx >> > 108: 61460 0 0 0 xen-dyn-event >> > vif1.1-q1-tx >> > 109: 1 0 0 0 xen-dyn-event >> > vif1.1-q1-rx >> > 110: 67118 0 0 0 xen-dyn-event >> > vif1.1-q2-tx >> > 111: 1 0 0 0 xen-dyn-event >> > vif1.1-q2-rx >> > 112: 58273 0 0 0 xen-dyn-event >> > vif1.1-q3-tx >> > 113: 1 0 0 0 xen-dyn-event >> > vif1.1-q3-rx >> > ... >> > >> > What would be the way to change smp_affinity? >> >> It should be via /proc/irq/<irq>/smp_affinity as you've tried, I asked >> Stefano and he things this was already implemented in 4.5 even. That it is >> not happening would be a bug, I think. >> >> I'd suggest you take this to the devel list as a bug. >> >> > and where is the affinity set initially for netback tx interrupts? >> >> Not, sure, I think it might just be generic IRQ code. >> >> Ian. >> >> >
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