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Thanks for reply.
Yes, our patch changes the est_list to a RCU list. Will do more testing and
send out the patch.
Thanks
—Yunhong
> On Apr 17, 2020, at 12:47 AM, Julian Anastasov <ja@xxxxxx> wrote:
>
>
> Hello,
>
> On Thu, 16 Apr 2020, yunhong-cgl jiang wrote:
>
>> Hi, Simon & Julian,
>> We noticed that on our kubernetes node utilizing IPVS, the
>> estimation_timer() takes very long (>200sm as shown below). Such long delay
>> on timer softirq causes long packet latency.
>>
>> <idle>-0 [007] dNH. 25652945.670814: softirq_raise: vec=1
>> [action=TIMER]
>> .....
>> <idle>-0 [007] .Ns. 25652945.992273: softirq_exit: vec=1
>> [action=TIMER]
>>
>> The long latency is caused by the big service number (>50k) and large
>> CPU number (>80 CPUs),
>>
>> We tried to move the timer function into a kernel thread so that it
>> will not block the system and seems solves our problem. Is this the right
>> direction? If yes, we will do more testing and send out the RFC patch. If
>> not, can you give us some suggestion?
>
> Using kernel thread is a good idea. For this to work, we can
> also remove the est_lock and to use RCU for est_list.
> The writers ip_vs_start_estimator() and ip_vs_stop_estimator() already
> run under common mutex __ip_vs_mutex, so they not need any
> synchronization. We need _bh lock usage in estimation_timer().
> Let me know if you need any help with the patch.
>
> Regards
>
> --
> Julian Anastasov <ja@xxxxxx>
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