netdev - Re: [PATCH net-next 7/9] net: openvswitch: add likely in flow

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Date:   Tue, 8 Oct 2019 11:21:51 +0800
From:   Tonghao Zhang <xiangxia.m.yue@...il.com>
To:     Pravin Shelar <pshelar@....org>
Cc:     Greg Rose <gvrose8192@...il.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 7/9] net: openvswitch: add likely in flow_lookup

On Wed, Oct 2, 2019 at 10:07 AM Pravin Shelar <pshelar@....org> wrote:
>
> On Sun, Sep 29, 2019 at 7:09 PM <xiangxia.m.yue@...il.com> wrote:
> >
> > From: Tonghao Zhang <xiangxia.m.yue@...il.com>
> >
> > The most case *index < ma->max, we add likely for performance.
> >
> > Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
> > ---
> >  net/openvswitch/flow_table.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> > index c8e79c1..c21fd52 100644
> > --- a/net/openvswitch/flow_table.c
> > +++ b/net/openvswitch/flow_table.c
> > @@ -526,7 +526,7 @@ static struct sw_flow *flow_lookup(struct flow_table *tbl,
> >         struct sw_flow_mask *mask;
> >         int i;
> >
> > -       if (*index < ma->max) {
> > +       if (likely(*index < ma->max)) {
>
> After changes from patch 5, ma->count is the limit for mask array. so
> why not use ma->count here.
because we will check the mask is valid, so use the ma->count and
ma->max are ok.
but i will use the ma->count in v2.
>
> >                 mask = rcu_dereference_ovsl(ma->masks[*index]);
> >                 if (mask) {
> >                         flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
> > --
> > 1.8.3.1
> >