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From: Morten Brørup <mb@smartsharesystems.com>
To: "Thomas Monjalon" <thomas@monjalon.net>, <dev@dpdk.org>
Cc: <david.marchand@redhat.com>, <ferruh.yigit@intel.com>,
	<olivier.matz@6wind.com>, <konstantin.ananyev@intel.com>,
	<andrew.rybchenko@oktetlabs.ru>, <viacheslavo@nvidia.com>,
	<ajit.khaparde@broadcom.com>, <jerinj@marvell.com>,
	<hemant.agrawal@nxp.com>, "Ray Kinsella" <mdr@ashroe.eu>,
	"Neil Horman" <nhorman@tuxdriver.com>
Subject: Re: [dpdk-dev] [PATCH v2 2/2] mbuf: move pool pointer in first half
Date: Tue, 10 Nov 2020 11:05:48 +0100
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35C6140F@smartserver.smartshare.dk> (raw)
In-Reply-To: <20201109212937.989954-3-thomas@monjalon.net>

> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Monday, November 9, 2020 10:30 PM
> 
> According to the Technical Board decision
> (http://mails.dpdk.org/archives/dev/2020-November/191859.html),
> the mempool pointer in the mbuf struct is moved
> from the second to the first half.
> It may increase performance in some cases
> on systems having 64-byte cache line, i.e. mbuf split in two cache
> lines.
> 
> Due to this change, tx_offload is moved.

A minor correction: All fields after m->pool are moved up 8 bytes, not only m->tx_offload.

> Hopefully no vector data path is impacted.
> 
> Moving this field gives more space to dynfield1
> while dropping the temporary dynfield0.
> 
> This is how the mbuf layout looks like (pahole-style):
> 
> word  type                              name                byte  size
>  0    void *                            buf_addr;         /*   0 +  8
> */
>  1    rte_iova_t                        buf_iova          /*   8 +  8
> */
>       /* --- RTE_MARKER64               rearm_data;
> */
>  2    uint16_t                          data_off;         /*  16 +  2
> */
>       uint16_t                          refcnt;           /*  18 +  2
> */
>       uint16_t                          nb_segs;          /*  20 +  2
> */
>       uint16_t                          port;             /*  22 +  2
> */
>  3    uint64_t                          ol_flags;         /*  24 +  8
> */
>       /* --- RTE_MARKER                 rx_descriptor_fields1;
> */
>  4    uint32_t             union        packet_type;      /*  32 +  4
> */
>       uint32_t                          pkt_len;          /*  36 +  4
> */
>  5    uint16_t                          data_len;         /*  40 +  2
> */
>       uint16_t                          vlan_tci;         /*  42 +  2
> */
>  5.5  uint64_t             union        hash;             /*  44 +  8
> */
>  6.5  uint16_t                          vlan_tci_outer;   /*  52 +  2
> */
>       uint16_t                          buf_len;          /*  54 +  2
> */
>  7    struct rte_mempool *              pool;             /*  56 +  8
> */
>       /* --- RTE_MARKER                 cacheline1;
> */
>  8    struct rte_mbuf *                 next;             /*  64 +  8
> */
>  9    uint64_t             union        tx_offload;       /*  72 +  8
> */
> 10    struct rte_mbuf_ext_shared_info * shinfo;           /*  80 +  8
> */
> 11    uint16_t                          priv_size;        /*  88 +  2
> */
>       uint16_t                          timesync;         /*  90 +  2
> */
> 11.5  uint32_t                          dynfield1[9];     /*  92 + 36
> */
> 16    /* --- END                                             128
> */
> 
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>

The minor detail doesn’t prevent...

Acked-by: Morten Brørup <mb@smartsharesystems.com>


  reply	other threads:[~2020-11-10 10:06 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-07 15:53 [dpdk-dev] [PATCH 1/1] " Thomas Monjalon
2020-11-07 17:12 ` Jerin Jacob
2020-11-07 18:39   ` Thomas Monjalon
2020-11-07 19:05     ` Jerin Jacob
2020-11-07 20:33       ` Thomas Monjalon
2020-11-09  5:18         ` Jerin Jacob
2020-11-09  8:04           ` Thomas Monjalon
2020-11-09  8:27             ` Jerin Jacob
2020-11-09  9:47               ` Bruce Richardson
2020-11-09 12:01                 ` Jerin Jacob
2020-11-09 12:59                   ` Thomas Monjalon
2020-11-09 13:35                     ` Jerin Jacob
2020-11-09 14:02                       ` Thomas Monjalon
2020-11-09 14:08                         ` Jerin Jacob
2020-11-09 14:42                           ` Thomas Monjalon
2020-11-09 14:53                             ` Jerin Jacob
2020-11-09  8:16           ` Morten Brørup
2020-11-09 10:06             ` [dpdk-dev] [dpdk-techboard] " Bruce Richardson
2020-11-09 10:21               ` Morten Brørup
2020-11-09 18:04                 ` Stephen Hemminger
2020-11-10  7:15                   ` Morten Brørup
2020-11-07 18:57 ` [dpdk-dev] " Morten Brørup
2020-11-09 10:08   ` Bruce Richardson
2020-11-09 10:30     ` Morten Brørup
2020-11-09 10:33     ` Ananyev, Konstantin
2020-11-09 10:36       ` Bruce Richardson
2020-11-09 11:24       ` Ananyev, Konstantin
2020-11-09 21:29 ` [dpdk-dev] [PATCH v2 0/2] move mbuf pool pointer Thomas Monjalon
2020-11-09 21:29   ` [dpdk-dev] [PATCH v2 1/2] drivers: disable OCTEON TX2 in 32-bit build Thomas Monjalon
2020-11-10 18:05     ` Jerin Jacob
2020-11-09 21:29   ` [dpdk-dev] [PATCH v2 2/2] mbuf: move pool pointer in first half Thomas Monjalon
2020-11-10 10:05     ` Morten Brørup [this message]
2020-11-10 10:44       ` Thomas Monjalon
2020-11-10 16:25     ` Olivier Matz
2020-11-10 18:06       ` Jerin Jacob
2020-11-12 14:39         ` Thomas Monjalon
2020-11-10 18:08       ` Stephen Hemminger

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