Best Regards,
liujian
> -----Original Message-----
> From: netdev-ow...@vger.kernel.org [mailto:netdev-ow...@vger.kernel.org]
> On Behalf Of Florian Westphal
> Sent: Tuesday, August 29, 2017 9:47 PM
> To: liujian (CE)
> Cc: Florian Westphal; Jesper Dangaard Brouer; netdev@vger.kernel.org;
> Wangkefeng (Kevin); weiyongjun (A)
> Subject: Re: Question about ip_defrag
>
> liujian (CE) <liujia...@huawei.com> wrote:
>
> [ trimming cc list ]
>
> > Now, I have not the real environment.
> > I use iperf generate fragment packets; and I always change NIC rx
> > irq's affinity cpu, to make sure frag_mem_limit reach to thresh.
> > my test machine, CPU num is 384.
>
> Oh well, that explains it.
>
> > > > + if (frag_mem_limit(nf) > nf->low_thresh) {
> > > > inet_frag_schedule_worker(f);
> > > > + update_frag_mem_limit(nf, SKB_TRUESIZE(1500) * 16);
> > > > + }
>
> You need to reduce this to a lower value.
> Your cpu count * batch_value needs to be less than low_thresh to avoid
> problems.
>
> Wtih 384 cpus its close to 12 mbyte...
>
> Perhaps do this:
>
> update_frag_mem_limit(nf, 2 * 1024*1024 / NR_CPUS);
>
>
> However, I think its better to revert the percpu counter change and move back
> to a single atomic_t count.
Ok.
Florian and Jesper, many thanks for this issue.
