netdev - 答复: 答复: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get

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Date:   Fri, 3 Sep 2021 04:00:04 +0000
From:   "Li,Rongqing" <lirongqing@...du.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>
Subject: 答复: 答复: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq



> -----邮件原件-----
> 发件人: Michael S. Tsirkin <mst@...hat.com>
> 发送时间: 2021年8月31日 22:34
> 收件人: Li,Rongqing <lirongqing@...du.com>
> 抄送: netdev@...r.kernel.org; bpf@...r.kernel.org;
> virtualization@...ts.linux-foundation.org
> 主题: Re: 答复: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in
> virtnet_xdp_get_sq
> 
> On Tue, Aug 31, 2021 at 02:09:36AM +0000, Li,Rongqing wrote:
> > > -----邮件原件-----
> > > 发件人: Michael S. Tsirkin <mst@...hat.com>
> > > 发送时间: 2021年8月31日 5:10
> > > 收件人: Li,Rongqing <lirongqing@...du.com>
> > > 抄送: netdev@...r.kernel.org; bpf@...r.kernel.org;
> > > virtualization@...ts.linux-foundation.org
> > > 主题: Re: [PATCH] virtio_net: reduce raw_smp_processor_id() calling in
> > > virtnet_xdp_get_sq
> > >
> > > On Thu, Aug 26, 2021 at 04:21:35PM +0800, Li RongQing wrote:
> > > > smp_processor_id()/raw* will be called once each when not more
> > > > queues in virtnet_xdp_get_sq() which is called in non-preemptible
> > > > context, so it's safe to call the function
> > > > smp_processor_id() once.
> > > >
> > > > Signed-off-by: Li RongQing <lirongqing@...du.com>
> > >
> > > commit log should probably explain why it's a good idea to replace
> > > raw_smp_processor_id with smp_processor_id in the case of
> > > curr_queue_pairs <= nr_cpu_ids.
> > >
> >
> >
> > I change it as below, is it ok?
> >
> >     virtio_net: reduce raw_smp_processor_id() calling in
> > virtnet_xdp_get_sq
> 
> shorter:
> 
> virtio_net: s/raw_smp_processor_id/smp_processor_id/ in virtnet_xdp_get_sq
> 
> 
> >
> >     smp_processor_id() and raw_smp_processor_id() are called once
> >     each in virtnet_xdp_get_sq(), when curr_queue_pairs <= nr_cpu_ids,
> >     should be merged
> 
> I'd just drop this part.
> 
> >
> >     virtnet_xdp_get_sq() is called in non-preemptible context, so
> >     it's safe to call the function smp_processor_id(), and keep
> >     smp_processor_id(), and remove the calling of raw_smp_processor_id(),
> >     avoid the wrong use virtnet_xdp_get_sq to preemptible context
> >     in the future
> 
> s/avoid.*/this way we'll get a warning if this is ever called in a preemptible
> context/
> 


Thanks, should I resend it

-Li


> 
> >
> > -Li