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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Tiwei Bie <tiwei.bie@intel.com>, Jens Freimann <jfreimann@redhat.com>
Cc: zhihong.wang@intel.com, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH 05/10] net/virtio: refactor virtqueue structure
Date: Tue, 19 Mar 2019 14:28:30 +0100	[thread overview]
Message-ID: <d7e82447-2748-0e15-c827-93e59516b3ad@redhat.com> (raw)
Message-ID: <20190319132830.deLhKvllx5zLy_fKPMqxcbweouEXCmunwzkYQmQ-nYg@z> (raw)
In-Reply-To: <20190319100939.GA3839@dpdk-tbie.sh.intel.com>



On 3/19/19 11:09 AM, Tiwei Bie wrote:
> On Tue, Mar 19, 2019 at 10:44:32AM +0100, Jens Freimann wrote:
>> On Tue, Mar 19, 2019 at 02:43:07PM +0800, Tiwei Bie wrote:
>>> Put split ring and packed ring specific fields into separate
>>> sub-structures, and also union them as they won't be available
>>> at the same time.
>>>
>>> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
>>> ---
>>> drivers/net/virtio/virtio_ethdev.c           | 71 +++++++++---------
>>> drivers/net/virtio/virtio_rxtx.c             | 66 ++++++++---------
>>> drivers/net/virtio/virtio_rxtx_simple.h      |  2 +-
>>> drivers/net/virtio/virtio_rxtx_simple_neon.c |  2 +-
>>> drivers/net/virtio/virtio_rxtx_simple_sse.c  |  2 +-
>>> drivers/net/virtio/virtqueue.c               |  6 +-
>>> drivers/net/virtio/virtqueue.h               | 77 +++++++++++---------
>>> 7 files changed, 117 insertions(+), 109 deletions(-)
>>>
>> [snip]
>> ...
>>> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
>>> index 80c0c43c3..48b3912e6 100644
>>> --- a/drivers/net/virtio/virtqueue.h
>>> +++ b/drivers/net/virtio/virtqueue.h
>>> @@ -191,17 +191,22 @@ struct vq_desc_extra {
>>>
>>> struct virtqueue {
>>> 	struct virtio_hw  *hw; /**< virtio_hw structure pointer. */
>>> -	struct vring vq_ring;  /**< vring keeping desc, used and avail */
>>> -	struct vring_packed ring_packed;  /**< vring keeping descs */
>>> -	bool used_wrap_counter;
>>> -	uint16_t cached_flags; /**< cached flags for descs */
>>> -	uint16_t event_flags_shadow;
>>> +	union {
>>> +		struct {
>>> +			/**< vring keeping desc, used and avail */
>>> +			struct vring ring;
>>> +		} vq_split;
>>>
>>> -	/**
>>> -	 * Last consumed descriptor in the used table,
>>> -	 * trails vq_ring.used->idx.
>>> -	 */
>>> -	uint16_t vq_used_cons_idx;
>>> +		struct {
>>> +			/**< vring keeping descs and events */
>>> +			struct vring_packed ring;
>>> +			bool used_wrap_counter;
>>> +			uint16_t cached_flags; /**< cached flags for descs */
>>> +			uint16_t event_flags_shadow;
>>> +		} vq_packed;
>>> +	};
>>> +
>>> +	uint16_t vq_used_cons_idx; /**< last consumed descriptor */
>>> 	uint16_t vq_nentries;  /**< vring desc numbers */
>>> 	uint16_t vq_free_cnt;  /**< num of desc available */
>>> 	uint16_t vq_avail_idx; /**< sync until needed */
>>
>> Honest question: What do we really gain by putting it in a union? We
>> save a little memory. But we also make code less readable IMHO.
> 
> I think it will make it clear that fields like used_wrap_counter
> are only available in packed ring which will make the code more
> readable.
> 
>>
>> If we do this, can we at least shorten some variable names, like drop
>> the vq_ prefix? (It's used everywhere like vq->vq_packed*, so with
>> vq->packed* we don't loose any context).
> 
> I prefer to have consistent prefix like most fields in this
> structure (although some fields don't really follow this).

As Jens, I tend to agree that the vq_ prefix is quite redundant.
However, I think it is better to keep it in this patch for consistency.

Maybe it can be remove in a separate patch later?

> Thanks,
> Tiwei
> 
>>
>> I'm not strictly against this change but I'm wondering if it's worth
>> it.
>>
>> regards,
>> Jens
>>

  parent reply	other threads:[~2019-03-19 13:28 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-19  6:43 [dpdk-dev] [PATCH 00/10] net/virtio: cleanups and fixes for packed/split ring Tiwei Bie
2019-03-19  6:43 ` Tiwei Bie
2019-03-19  6:43 ` [dpdk-dev] [PATCH 01/10] net/virtio: fix typo in packed ring init Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19  8:39   ` Jens Freimann
2019-03-19  8:39     ` Jens Freimann
2019-03-19 12:46   ` Maxime Coquelin
2019-03-19 12:46     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 02/10] net/virtio: fix interrupt helper for packed ring Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19 12:48   ` Maxime Coquelin
2019-03-19 12:48     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 03/10] net/virtio: add missing barrier in interrupt enable Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19 12:49   ` Maxime Coquelin
2019-03-19 12:49     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 04/10] net/virtio: optimize flags update for packed ring Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19  8:54   ` Jens Freimann
2019-03-19  8:54     ` Jens Freimann
2019-03-19  9:37     ` Tiwei Bie
2019-03-19  9:37       ` Tiwei Bie
2019-03-19 10:11       ` Jens Freimann
2019-03-19 10:11         ` Jens Freimann
2019-03-19 12:50         ` Maxime Coquelin
2019-03-19 12:50           ` Maxime Coquelin
2019-03-19 12:58   ` Maxime Coquelin
2019-03-19 12:58     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 05/10] net/virtio: refactor virtqueue structure Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19  9:44   ` Jens Freimann
2019-03-19  9:44     ` Jens Freimann
2019-03-19 10:09     ` Tiwei Bie
2019-03-19 10:09       ` Tiwei Bie
2019-03-19 13:28       ` Maxime Coquelin [this message]
2019-03-19 13:28         ` Maxime Coquelin
2019-03-19 13:47         ` Jens Freimann
2019-03-19 13:47           ` Jens Freimann
2019-03-19 13:50           ` Maxime Coquelin
2019-03-19 13:50             ` Maxime Coquelin
2019-03-19 14:59             ` Kevin Traynor
2019-03-19 14:59               ` Kevin Traynor
2019-03-20  4:40               ` Tiwei Bie
2019-03-20  4:40                 ` Tiwei Bie
2019-03-20 17:50                 ` Stephen Hemminger
2019-03-20 17:50                   ` Stephen Hemminger
2019-03-21 14:18                   ` Maxime Coquelin
2019-03-21 14:18                     ` Maxime Coquelin
2019-03-20  4:35         ` Tiwei Bie
2019-03-20  4:35           ` Tiwei Bie
2019-03-19 13:28   ` Maxime Coquelin
2019-03-19 13:28     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 06/10] net/virtio: drop redundant suffix in packed ring structure Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19  9:47   ` Jens Freimann
2019-03-19  9:47     ` Jens Freimann
2019-03-19 13:29   ` Maxime Coquelin
2019-03-19 13:29     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 07/10] net/virtio: drop unused field in Tx region structure Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19  9:51   ` Jens Freimann
2019-03-19  9:51     ` Jens Freimann
2019-03-19 13:33   ` Maxime Coquelin
2019-03-19 13:33     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 08/10] net/virtio: add interrupt helper for split ring Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19  9:53   ` Jens Freimann
2019-03-19  9:53     ` Jens Freimann
2019-03-19 13:34   ` Maxime Coquelin
2019-03-19 13:34     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 09/10] net/virtio: add ctrl vq " Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19  9:54   ` Jens Freimann
2019-03-19  9:54     ` Jens Freimann
2019-03-19 13:54   ` Maxime Coquelin
2019-03-19 13:54     ` Maxime Coquelin
2019-03-19  6:43 ` [dpdk-dev] [PATCH 10/10] net/virtio: improve batching in standard Rx path Tiwei Bie
2019-03-19  6:43   ` Tiwei Bie
2019-03-19 10:04   ` Jens Freimann
2019-03-19 10:04     ` Jens Freimann
2019-03-19 10:28     ` Tiwei Bie
2019-03-19 10:28       ` Tiwei Bie
2019-03-19 11:08       ` Maxime Coquelin
2019-03-19 11:08         ` Maxime Coquelin
2019-03-19 14:15   ` Maxime Coquelin
2019-03-19 14:15     ` Maxime Coquelin
2019-03-20  7:35 ` [dpdk-dev] [PATCH 00/10] net/virtio: cleanups and fixes for packed/split ring Maxime Coquelin
2019-03-20  7:35   ` Maxime Coquelin

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