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From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: dev@dpdk.org, Panu Matilainen <pmatilai@redhat.com>,
	"Yang, Zhiyong" <zhiyong.yang@intel.com>
Subject: Re: [dpdk-dev] [PATCH] vhost: add pmd xstats
Date: Wed, 24 Aug 2016 10:44:33 +0200	[thread overview]
Message-ID: <3180838.i4arGqJgvX@xps13> (raw)
In-Reply-To: <20160824054602.GS30752@yliu-dev.sh.intel.com>

2016-08-24 13:46, Yuanhan Liu:
> On Tue, Aug 23, 2016 at 12:45:54PM +0300, Panu Matilainen wrote:
> > >>>Since collecting data of vhost_update_packet_xstats will have some
> > >>>effect on RX/TX performance, so, Setting compiling switch
> > >>>CONFIG_RTE_LIBRTE_PMD_VHOST_UPDATE_XSTATS=n by default in the
> > >>file
> > >>>config/common_base, if needing xstats data, you can enable it(y).
> > >>
> > >>NAK, such things need to be switchable at run-time.
> > >>
> > >>	- Panu -
> > >
> > >Considering the following reasons using the compiler switch, not
> > >command-line at run-time.
> > >
> > >1.Similar xstats update functions are always collecting stats data in the
> > >background when rx/tx are running, such as the physical NIC or virtio,
> > >which have no switch. Compiler switch for vhost pmd xstats is added
> > >as a option when performance is viewed as critical factor.
> > >
> > >2. No data structure and API in any layer support the xstats update switch
> > >at run-time. Common data structure (struct rte_eth_dev_data) has no
> > >device-specific data member, if implementing enable/disable of vhost_update
> > >_packet_xstats at run-time, must define a flag(device-specific) in it,
> > >because the definition of struct vhost_queue in the driver code
> > >(eth_vhost_rx/eth_vhost_tx processing)is not visible from device perspective.
> > >
> > >3. I tested RX/TX with v1 patch (y) as reference based on Intel(R)
> > >Xeon(R) CPU E5-2699 v3 @ 2.30GHz, for 64byts packets in burst mode, 32 packets
> > >in one RX/TX processing. Overhead of vhost_update_packet_xstats is less than
> > >3% for the rx/tx processing. It looks that vhost_update_packet_xstats has a
> > >limited effect on performance drop.
> > 
> > Well, either the performance overhead is acceptable and it should always be
> > on (like with physical NICs I think). Or it is not. In which case it needs
> > to be turnable on and off, at run-time. Rebuilding is not an option in the
> > world of distros.
> 
> I think the less than 3% overhead is acceptable here, that I agree with
> Panu we should always keep it on. If someone compains it later that even
> 3% is too big for them, let's consider to make it be switchable at
> run-time. Either we could introduce a generic eth API for that, Or
> just introduce a vhost one if that doesn't make too much sense to other
> eth drivers.

+1
It may have sense to introduce a generic run-time option for stats.

  reply	other threads:[~2016-08-24  8:44 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-19 12:16 Zhiyong Yang
2016-08-22  7:52 ` Panu Matilainen
2016-08-23  8:04   ` Yang, Zhiyong
2016-08-23  9:45     ` Panu Matilainen
2016-08-24  5:46       ` Yuanhan Liu
2016-08-24  8:44         ` Thomas Monjalon [this message]
2016-08-24 12:37           ` Panu Matilainen
2016-08-25  9:21             ` Yang, Zhiyong
2016-08-30  2:45               ` Yao, Lei A
2016-08-30  3:03                 ` Xu, Qian Q
2016-08-30  3:21                   ` Yao, Lei A
2016-08-31  7:18                     ` Yang, Zhiyong
2016-09-01  6:37                       ` Yang, Zhiyong
2016-09-09  8:15 ` [dpdk-dev] [PATCH v2] net/vhost: " Zhiyong Yang
2016-09-09  8:40   ` Van Haaren, Harry
2016-09-09  8:54     ` Yang, Zhiyong
2016-09-14  6:20   ` Yuanhan Liu
2016-09-14  7:43     ` Yang, Zhiyong
2016-09-18 13:16       ` Yuanhan Liu
2016-09-19  2:48         ` Yang, Zhiyong
2016-09-14  8:30     ` Yang, Zhiyong
2016-09-20  9:36   ` [dpdk-dev] [PATCH v3 0/2] net/vhost: add pmd xstats support Zhiyong Yang
2016-09-20  9:36     ` [dpdk-dev] [PATCH v3 1/2] net/vhost: add a new stats struct Zhiyong Yang
2016-09-20 10:44       ` Yuanhan Liu
2016-09-21  5:12         ` Yang, Zhiyong
2016-09-21 10:05       ` [dpdk-dev] [PATCH v4 0/2] net/vhost: add pmd xstats support Zhiyong Yang
2016-09-21 10:05         ` Zhiyong Yang
2016-09-21 10:05         ` [dpdk-dev] [PATCH v4 2/2] net/vhost: add pmd xstats Zhiyong Yang
2016-09-21 10:57           ` Yuanhan Liu
2016-09-22  1:42             ` Yang, Zhiyong
2016-09-22  2:09               ` Yuanhan Liu
2016-09-21 10:13       ` [dpdk-dev] [PATCH v4 1/2] net/vhost: add a new defined stats struct Zhiyong Yang
2016-09-22  8:19         ` [dpdk-dev] [PATCH v5 0/2] net/vhost: add pmd xstats support Zhiyong Yang
2016-09-22  8:19           ` [dpdk-dev] [PATCH v5 1/2] net/vhost: add a new defined stats struct Zhiyong Yang
2016-09-28  8:33             ` [dpdk-dev] [PATCH v6 0/2] net/vhost: add pmd xstats support Zhiyong Yang
2016-09-28  8:33               ` [dpdk-dev] [PATCH v6 1/2] net/vhost: add a new defined stats struct Zhiyong Yang
2016-09-28 13:26                 ` [dpdk-dev] [PATCH v7 0/2] net/vhost: add pmd xstats support Zhiyong Yang
2016-09-28 13:26                   ` [dpdk-dev] [PATCH v7 1/2] net/vhost: add a new defined stats struct Zhiyong Yang
2016-09-29  1:55                     ` Yuanhan Liu
2016-09-29 12:35                     ` [dpdk-dev] [PATCH v8 0/2] net/vhost: add pmd xstats support Zhiyong Yang
2016-09-29 12:35                       ` [dpdk-dev] [PATCH v8 1/2] net/vhost: add a new defined stats struct Zhiyong Yang
2016-09-29 12:35                       ` [dpdk-dev] [PATCH v8 2/2] net/vhost: add pmd xstats Zhiyong Yang
2016-09-29 13:04                         ` Yuanhan Liu
2016-09-29 13:50                           ` Yang, Zhiyong
2016-09-28 13:26                   ` [dpdk-dev] [PATCH v7 " Zhiyong Yang
2016-09-29  8:48                     ` Loftus, Ciara
2016-09-29 12:02                       ` Yuanhan Liu
2016-09-29 12:22                         ` Yang, Zhiyong
2016-09-28  8:33               ` [dpdk-dev] [PATCH v6 " Zhiyong Yang
2016-09-22  8:19           ` [dpdk-dev] [PATCH v5 " Zhiyong Yang
2016-09-23  3:56           ` [dpdk-dev] [PATCH v5 0/2] net/vhost: add pmd xstats support Yuanhan Liu
2016-09-28  2:35             ` Yuanhan Liu
2016-09-20  9:36     ` [dpdk-dev] [PATCH v3 2/2] net/vhost: add pmd xstats Zhiyong Yang
2016-09-20 10:56       ` Yuanhan Liu
2016-09-21  7:22         ` Yang, Zhiyong
2016-09-20 11:50       ` Yuanhan Liu
2016-09-21  6:15         ` Yang, Zhiyong

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