From: Yongseok Koh <yskoh@mellanox.com>
To: Olivier Matz <olivier.matz@6wind.com>
Cc: Andrew Rybchenko <arybchenko@solarflare.com>,
wenzhuo.lu@intel.com, jingjing.wu@intel.com, dev@dpdk.org,
konstantin.ananyev@intel.com, adrien.mazarguil@6wind.com,
nelio.laranjeiro@6wind.com, Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [dpdk-dev] [PATCH v4 1/2] mbuf: support attaching external buffer to mbuf
Date: Tue, 24 Apr 2018 16:34:43 -0700 [thread overview]
Message-ID: <20180424233442.GC88208@yongseok-MBP.local> (raw)
In-Reply-To: <20180424191538.exjgzoif4odhndew@neon>
On Tue, Apr 24, 2018 at 09:15:38PM +0200, Olivier Matz wrote:
> On Tue, Apr 24, 2018 at 09:21:00PM +0300, Andrew Rybchenko wrote:
> > On 04/24/2018 07:02 PM, Olivier Matz wrote:
> > > Hi Andrew, Yongseok,
> > >
> > > On Tue, Apr 24, 2018 at 03:28:33PM +0300, Andrew Rybchenko wrote:
> > > > On 04/24/2018 04:38 AM, Yongseok Koh wrote:
[...]
> > > > > + m->buf_addr = buf_addr;
> > > > > + m->buf_iova = buf_iova;
> > > > > +
> > > > > + if (shinfo == NULL) {
> > > > > + shinfo = RTE_PTR_ALIGN_FLOOR(RTE_PTR_SUB(buf_end,
> > > > > + sizeof(*shinfo)), sizeof(uintptr_t));
> > > > > + if ((void *)shinfo <= buf_addr)
> > > > > + return NULL;
> > > > > +
> > > > > + m->buf_len = RTE_PTR_DIFF(shinfo, buf_addr);
> > > > > + } else {
> > > > > + m->buf_len = buf_len;
> > > > > + }
> > > > > +
> > > > > + m->data_len = 0;
> > > > > +
> > > > > + rte_pktmbuf_reset_headroom(m);
> > > > I would suggest to make data_off one more parameter.
> > > > If I have a buffer with data which I'd like to attach to an mbuf, I'd like
> > > > to control data_off.
> > > Another option is to set the headroom to 0.
> > > Because the after attaching the mbuf to an external buffer, we will
> > > still require to set the length.
> > >
> > > A user can do something like this:
> > >
> > > rte_pktmbuf_attach_extbuf(m, buf_va, buf_iova, buf_len, shinfo,
> > > free_cb, free_cb_arg);
> > > rte_pktmbuf_append(m, data_len + headroom);
> > > rte_pktmbuf_adj(m, headroom);
I'd take this option. Will make the change and document it.
> > > > > + m->ol_flags |= EXT_ATTACHED_MBUF;
> > > > > + m->shinfo = shinfo;
> > > > > +
> > > > > + rte_mbuf_ext_refcnt_set(shinfo, 1);
> > > > Why is assignment used here? Cannot we attach extbuf already attached to
> > > > other mbuf?
> > > In rte_pktmbuf_attach(), this is true. That's not illogical to
> > > keep the same approach here. Maybe an assert could be added?
Like I described in the doc, intention is to attach external buffer by
_attach_extbuf() for the first time and _attach() is just for additional mbuf
attachment. Will add an assert.
> > > > May be shinfo should be initialized only if it is not provided (shinfo ==
> > > > NULL on input)?
> > > I don't get why, can you explain please?
> >
> > May be I misunderstand how it should look like when one huge buffer
> > is partitioned. I thought that it should be only one shinfo per huge buffer
> > to control when it is not used any more by any mbufs with extbuf.
>
> OK I got it.
>
> I think both approach could make sense:
> - one shinfo per huge buffer
> - or one shinfo per mbuf, and use the callback to manage another refcnt
> (like what Yongseok described)
>
> So I agree with your proposal, shinfo should be initialized by
> the caller if it is != NULL, else it can be initialized by
> rte_pktmbuf_attach_extbuf().
Also agreed. Will change.
> > Other option is to have shinfo per small buf plus reference counter
> > per huge buf (which is decremented when small buf reference counter
> > becomes zero and free callback is executed). I guess it is assumed above.
> > My fear is that it is too much reference counters:
> > 1. mbuf reference counter
> > 2. small buf reference counter
> > 3. huge buf reference counter
> > May be it is possible use (1) for (2) as well?
>
> I would prefer to have only 2 reference counters, one in the mbuf
> and one in the shinfo.
Good discussion. It should be a design decision by user.
In my use-case, it would be a good idea to make all the mbufs in a same chunk
point to the same shared info in the head of the chunk and reset the refcnt of
shinfo to the total number of slices in the chunk.
+--+----+----+--------------+----+--------------+---+- - -
|global |head|mbuf1 data |head|mbuf2 data | |
| shinfo|room| |room| | |
+--+----+----+--------------+----+--------------+---+- - -
Thanks,
Yongseok
next prev parent reply other threads:[~2018-04-24 23:35 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-10 1:25 [dpdk-dev] [PATCH v1 0/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-03-10 1:25 ` [dpdk-dev] [PATCH v1 1/6] mbuf: add buffer offset field for flexible indirection Yongseok Koh
2018-03-10 1:25 ` [dpdk-dev] [PATCH v1 2/6] net/mlx5: separate filling Rx flags Yongseok Koh
2018-03-10 1:25 ` [dpdk-dev] [PATCH v1 3/6] net/mlx5: add a function to rdma-core glue Yongseok Koh
2018-03-12 9:13 ` Nélio Laranjeiro
2018-03-10 1:25 ` [dpdk-dev] [PATCH v1 4/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-03-12 9:20 ` Nélio Laranjeiro
2018-03-10 1:25 ` [dpdk-dev] [PATCH v1 5/6] net/mlx5: release Tx queue resource earlier than Rx Yongseok Koh
2018-03-10 1:25 ` [dpdk-dev] [PATCH v1 6/6] app/testpmd: conserve mbuf indirection flag Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 0/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 1/6] mbuf: add buffer offset field for flexible indirection Yongseok Koh
2018-04-03 8:26 ` Olivier Matz
2018-04-04 0:12 ` Yongseok Koh
2018-04-09 16:04 ` Olivier Matz
2018-04-10 1:59 ` Yongseok Koh
2018-04-11 0:25 ` Ananyev, Konstantin
2018-04-11 5:33 ` Yongseok Koh
2018-04-11 11:39 ` Ananyev, Konstantin
2018-04-11 14:02 ` Andrew Rybchenko
2018-04-11 17:18 ` Yongseok Koh
2018-04-11 17:08 ` Yongseok Koh
2018-04-12 16:34 ` Ananyev, Konstantin
2018-04-12 18:58 ` Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 2/6] net/mlx5: separate filling Rx flags Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 3/6] net/mlx5: add a function to rdma-core glue Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 4/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 5/6] net/mlx5: release Tx queue resource earlier than Rx Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 6/6] app/testpmd: conserve mbuf indirection flag Yongseok Koh
2018-04-19 1:11 ` [dpdk-dev] [PATCH v3 1/2] mbuf: support attaching external buffer to mbuf Yongseok Koh
2018-04-19 1:11 ` [dpdk-dev] [PATCH v3 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-23 11:53 ` [dpdk-dev] [PATCH v3 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-24 2:04 ` Yongseok Koh
2018-04-25 13:16 ` Ananyev, Konstantin
2018-04-25 16:44 ` Yongseok Koh
2018-04-25 18:05 ` Ananyev, Konstantin
2018-04-23 16:18 ` Olivier Matz
2018-04-24 1:29 ` Yongseok Koh
2018-04-24 15:36 ` Olivier Matz
2018-04-24 1:38 ` [dpdk-dev] [PATCH v4 " Yongseok Koh
2018-04-24 1:38 ` [dpdk-dev] [PATCH v4 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-24 5:01 ` [dpdk-dev] [PATCH v4 1/2] mbuf: support attaching external buffer to mbuf Stephen Hemminger
2018-04-24 11:47 ` Yongseok Koh
2018-04-24 12:28 ` Andrew Rybchenko
2018-04-24 16:02 ` Olivier Matz
2018-04-24 18:21 ` [dpdk-dev] ***Spam*** " Andrew Rybchenko
2018-04-24 19:15 ` [dpdk-dev] " Olivier Matz
2018-04-24 20:22 ` Thomas Monjalon
2018-04-24 21:53 ` Yongseok Koh
2018-04-24 22:15 ` Thomas Monjalon
2018-04-25 8:21 ` Olivier Matz
2018-04-25 15:06 ` Stephen Hemminger
2018-04-24 23:34 ` Yongseok Koh [this message]
2018-04-25 14:45 ` Andrew Rybchenko
2018-04-25 17:40 ` Yongseok Koh
2018-04-25 8:28 ` Olivier Matz
2018-04-25 9:08 ` Yongseok Koh
2018-04-25 9:19 ` Yongseok Koh
2018-04-25 20:00 ` Olivier Matz
2018-04-25 22:54 ` Yongseok Koh
2018-04-24 22:30 ` Yongseok Koh
2018-04-25 2:53 ` [dpdk-dev] [PATCH v5 " Yongseok Koh
2018-04-25 2:53 ` [dpdk-dev] [PATCH v5 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-25 13:31 ` [dpdk-dev] [PATCH v5 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-25 17:06 ` Yongseok Koh
2018-04-25 17:23 ` Ananyev, Konstantin
2018-04-25 18:02 ` Yongseok Koh
2018-04-25 18:22 ` Yongseok Koh
2018-04-25 18:30 ` Yongseok Koh
2018-04-26 1:10 ` [dpdk-dev] [PATCH v6 " Yongseok Koh
2018-04-26 1:10 ` [dpdk-dev] [PATCH v6 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-26 11:39 ` [dpdk-dev] [PATCH v6 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-26 16:05 ` Andrew Rybchenko
2018-04-26 16:10 ` Thomas Monjalon
2018-04-26 19:42 ` Olivier Matz
2018-04-26 19:58 ` Thomas Monjalon
2018-04-26 20:07 ` Olivier Matz
2018-04-26 20:24 ` Thomas Monjalon
2018-04-26 17:18 ` Yongseok Koh
2018-04-26 19:45 ` Olivier Matz
2018-04-27 0:01 ` [dpdk-dev] [PATCH v7 " Yongseok Koh
2018-04-27 0:01 ` [dpdk-dev] [PATCH v7 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-27 8:00 ` Andrew Rybchenko
2018-04-27 7:22 ` [dpdk-dev] [PATCH v7 1/2] mbuf: support attaching external buffer to mbuf Andrew Rybchenko
2018-04-27 17:22 ` [dpdk-dev] [PATCH v8 " Yongseok Koh
2018-04-27 17:22 ` [dpdk-dev] [PATCH v8 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-27 18:09 ` [dpdk-dev] [PATCH v8 1/2] mbuf: support attaching external buffer to mbuf Thomas Monjalon
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