lkml.org 
[lkml]   [2020]   [Sep]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH net-next 6/6] net: hns3: use napi_consume_skb() when cleaning tx desc
On Wed, Sep 16, 2020 at 10:33 AM Saeed Mahameed <saeed@kernel.org> wrote:
>
> On Tue, 2020-09-15 at 15:04 +0800, Yunsheng Lin wrote:
> > On 2020/9/15 13:09, Saeed Mahameed wrote:
> > > On Mon, 2020-09-14 at 20:06 +0800, Huazhong Tan wrote:
> > > > From: Yunsheng Lin <linyunsheng@huawei.com>
> > > >
> > > > Use napi_consume_skb() to batch consuming skb when cleaning
> > > > tx desc in NAPI polling.
> > > >
> > > > Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
> > > > Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
> > > > ---
> > > > drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 27
> > > > +++++++++++-
> > > > ----------
> > > > drivers/net/ethernet/hisilicon/hns3/hns3_enet.h | 2 +-
> > > > drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c | 4 ++--
> > > > 3 files changed, 17 insertions(+), 16 deletions(-)
> > > >
> > > > diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> > > > b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> > > > index 4a49a76..feeaf75 100644
> > > > --- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> > > > +++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> > > > @@ -2333,10 +2333,10 @@ static int hns3_alloc_buffer(struct
> > > > hns3_enet_ring *ring,
> > > > }
> > > >
> > > > static void hns3_free_buffer(struct hns3_enet_ring *ring,
> > > > - struct hns3_desc_cb *cb)
> > > > + struct hns3_desc_cb *cb, int budget)
> > > > {
> > > > if (cb->type == DESC_TYPE_SKB)
> > > > - dev_kfree_skb_any((struct sk_buff *)cb->priv);
> > > > + napi_consume_skb(cb->priv, budget);
> > >
> > > This code can be reached from hns3_lb_clear_tx_ring() below which
> > > is
> > > your loopback test and called with non-zero budget, I am not sure
> > > you
> > > are allowed to call napi_consume_skb() with non-zero budget outside
> > > napi context, perhaps the cb->type for loopback test is different
> > > in lb
> > > test case ? Idk.. , please double check other code paths.
> >
> > Yes, loopback test may call napi_consume_skb() with non-zero budget
> > outside
> > napi context. Thanks for pointing out this case.
> >
> > How about add the below WARN_ONCE() in napi_consume_skb() to catch
> > this
> > kind of error?
> >
> > WARN_ONCE(!in_serving_softirq(), "napi_consume_skb() is called with
> > non-zero budget outside napi context");
> >
>
> Cc: Eric
>
> I don't know, need to check performance impact.
> And in_serving_softirq() doesn't necessarily mean in napi
> but looking at _kfree_skb_defer(), i think it shouldn't care if napi or
> not as long as it runs in soft irq it will push the skb to that
> particular cpu napi_alloc_cache, which should be fine.
>
> Maybe instead of the WARN_ONCE just remove the budget condition and
> replace it with
>
> if (!in_serving_softirq())
> dev_consume_skb_any(skb);
>

I think we need to keep costs small.

So lets add a CONFIG_DEBUG_NET option so that developers can add
various DEBUG_NET() clauses.

\
 
 \ /
  Last update: 2020-09-16 10:40    [W:0.058 / U:3.680 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site