> -----邮件原件----- > 发件人: Eric Dumazet [mailto:eric.duma...@gmail.com] > 发送时间: 2018年7月11日 19:32 > 收件人: Li,Rongqing <lirongq...@baidu.com>; netdev@vger.kernel.org > 主题: Re: [PATCH] net: convert gro_count to bitmask > > > > On 07/11/2018 02:15 AM, Li RongQing wrote: > > gro_hash size is 192 bytes, and uses 3 cache lines, if there is few > > flows, gro_hash may be not fully used, so it is unnecessary to iterate > > all gro_hash in napi_gro_flush(), to occupy unnecessary cacheline. > > > > convert gro_count to a bitmask, and rename it as gro_bitmask, each bit > > represents a element of gro_hash, only flush a gro_hash element if the > > related bit is set, to speed up napi_gro_flush(). > > > > and update gro_bitmask only if it will be changed, to reduce cache > > update > > > > Suggested-by: Eric Dumazet <eduma...@google.com> > > Signed-off-by: Li RongQing <lirongq...@baidu.com> > > --- > > include/linux/netdevice.h | 2 +- > > net/core/dev.c | 35 +++++++++++++++++++++++------------ > > 2 files changed, 24 insertions(+), 13 deletions(-) > > > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > > index b683971e500d..df49b36ef378 100644 > > --- a/include/linux/netdevice.h > > +++ b/include/linux/netdevice.h > > @@ -322,7 +322,7 @@ struct napi_struct { > > > > unsigned long state; > > int weight; > > - unsigned int gro_count; > > + unsigned long gro_bitmask; > > int (*poll)(struct napi_struct *, int); > > #ifdef CONFIG_NETPOLL > > int poll_owner; > > diff --git a/net/core/dev.c b/net/core/dev.c index > > d13cddcac41f..a08dbdd217a6 100644 > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -5171,9 +5171,11 @@ static void __napi_gro_flush_chain(struct > napi_struct *napi, u32 index, > > return; > > list_del_init(&skb->list); > > napi_gro_complete(skb); > > - napi->gro_count--; > > napi->gro_hash[index].count--; > > } > > + > > + if (!napi->gro_hash[index].count) > > + clear_bit(index, &napi->gro_bitmask); > > I suggest you not add an atomic operation here. > > Current cpu owns this NAPI after all. > > Same remark for the whole patch. > > -> __clear_bit(), __set_bit() and similar operators > > Ideally you should provide TCP_RR number with busy polling enabled, to > eventually catch regressions. >
I will change and do the test Thank you. -RongQing > Thanks.
