Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752881AbaGQCzt (ORCPT ); Wed, 16 Jul 2014 22:55:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13500 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbaGQCzq (ORCPT ); Wed, 16 Jul 2014 22:55:46 -0400 Message-ID: <53C73B29.4070107@redhat.com> Date: Thu, 17 Jul 2014 10:55:37 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Varka Bhadram , rusty@rustcorp.com.au, mst@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org CC: Vlad Yasevich , Eric Dumazet Subject: Re: [PATCH net-next V2 3/3] virtio-net: rx busy polling support References: <1405491707-22706-1-git-send-email-jasowang@redhat.com> <1405491707-22706-4-git-send-email-jasowang@redhat.com> <53C63A11.4050401@gmail.com> In-Reply-To: <53C63A11.4050401@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/16/2014 04:38 PM, Varka Bhadram wrote: > On 07/16/2014 11:51 AM, Jason Wang wrote: >> Add basic support for rx busy polling. >> >> Test was done between a kvm guest and an external host. Two hosts were >> connected through 40gb mlx4 cards. With both busy_poll and busy_read >> are set to 50 in guest, 1 byte netperf tcp_rr shows 116% improvement: >> transaction rate was increased from 9151.94 to 19787.37. >> >> Cc: Rusty Russell >> Cc: Michael S. Tsirkin >> Cc: Vlad Yasevich >> Cc: Eric Dumazet >> Signed-off-by: Jason Wang >> --- >> drivers/net/virtio_net.c | 190 >> ++++++++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 187 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >> index e417d93..4830713 100644 >> --- a/drivers/net/virtio_net.c >> +++ b/drivers/net/virtio_net.c >> @@ -27,6 +27,7 @@ >> #include >> #include >> #include >> +#include >> static int napi_weight = NAPI_POLL_WEIGHT; >> module_param(napi_weight, int, 0444); >> @@ -94,8 +95,143 @@ struct receive_queue { >> /* Name of this receive queue: input.$index */ >> char name[40]; >> + >> +#ifdef CONFIG_NET_RX_BUSY_POLL >> + unsigned int state; >> +#define VIRTNET_RQ_STATE_IDLE 0 >> +#define VIRTNET_RQ_STATE_NAPI 1 /* NAPI or refill owns >> this RQ */ >> +#define VIRTNET_RQ_STATE_POLL 2 /* poll owns this RQ */ >> +#define VIRTNET_RQ_STATE_DISABLED 4 /* RQ is disabled */ >> +#define VIRTNET_RQ_OWNED (VIRTNET_RQ_STATE_NAPI | >> VIRTNET_RQ_STATE_POLL) >> +#define VIRTNET_RQ_LOCKED (VIRTNET_RQ_OWNED | >> VIRTNET_RQ_STATE_DISABLED) >> +#define VIRTNET_RQ_STATE_NAPI_YIELD 8 /* NAPI or refill yielded >> this RQ */ >> +#define VIRTNET_RQ_STATE_POLL_YIELD 16 /* poll yielded this RQ */ >> + spinlock_t lock; >> +#endif /* CONFIG_NET_RX_BUSY_POLL */ >> }; >> +#ifdef CONFIG_NET_RX_BUSY_POLL >> +static inline void virtnet_rq_init_lock(struct receive_queue *rq) >> +{ >> + >> + spin_lock_init(&rq->lock); >> + rq->state = VIRTNET_RQ_STATE_IDLE; >> +} >> + >> +/* called from the device poll routine or refill routine to get >> ownership of a >> + * receive queue. >> + */ >> +static inline bool virtnet_rq_lock_napi_refill(struct receive_queue >> *rq) >> +{ >> + int rc = true; >> + > > bool instead of int...? Yes, it was better. > >> + spin_lock(&rq->lock); >> + if (rq->state & VIRTNET_RQ_LOCKED) { >> + WARN_ON(rq->state & VIRTNET_RQ_STATE_NAPI); >> + rq->state |= VIRTNET_RQ_STATE_NAPI_YIELD; >> + rc = false; >> + } else >> + /* we don't care if someone yielded */ >> + rq->state = VIRTNET_RQ_STATE_NAPI; >> + spin_unlock(&rq->lock); > > Lock for rq->state ...? > > If yes: > spin_lock(&rq->lock); > if (rq->state & VIRTNET_RQ_LOCKED) { > rq->state |= VIRTNET_RQ_STATE_NAPI_YIELD; > spin_unlock(&rq->lock); > WARN_ON(rq->state & VIRTNET_RQ_STATE_NAPI); > rc = false; > } else { > /* we don't care if someone yielded */ > rq->state = VIRTNET_RQ_STATE_NAPI; > spin_unlock(&rq->lock); > } I didn't see any differences. Is this used to catch the bug of driver earlier? btw, several other rx busy polling capable driver does the same thing. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/