From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: dev@dpdk.org, Hiroyuki Mikita <h.mikita89@gmail.com>,
olivier.matz@6wind.com
Subject: Re: [dpdk-dev] [PATCH v2] mbuf: decrease refcnt when detaching
Date: Tue, 17 May 2016 16:19:17 +0200 [thread overview]
Message-ID: <3377984.UT2r9Befy8@xps13> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB97725836B518CE@irsmsx105.ger.corp.intel.com>
2016-05-17 13:44, Ananyev, Konstantin:
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > 2016-05-17 12:59, Ananyev, Konstantin:
> > > > > The rte_pktmbuf_detach() function should decrease refcnt on a direct
> > > > > buffer.
> > > >
> > > > As you have noticed, "whenever the indirect buffer is detached,
> > > > the reference counter on the direct buffer is decremented."
> > > > So the current behaviour of rte_pktmbuf_detach() is buggy.
> > > > Why not fix it without renaming?
> > > > If you consider this behavioral bug is part of the API, we
> > > > can fix it in a new function unattach and deprecate detach.
> > > > But Konstantin, why do you want to keep a restore function?
> > > > What is the need?
> > >
> > > I think it might be a useful functionality in some situations:
> > > some users can attach/detach to external memory buffers (no mbufs)
> > > and similar functionality is required.
> >
> > Attach to external memory buffer (raw buffer) is not currently supported.
> >
> > > Let say right now examples/vhost/main.c has its own pktmbuf_detach_zcp()
> >
> > You should look at the commit http://dpdk.org/commit/68363d85
> > "examples/vhost: remove the non-working zero copy code"
> >
> > > which is doing pretty much the same - restore original values, after detaching
> > > mbuf from external (virtio) memory buffer.
> > > Would be good if we'll use a standard API function here.
> >
> > You are welcome to implement mbuf attach to raw buffer.
> > But it is not a requirement for this fix.
>
> Hmm, still not sure why we can't keep an existing function?
Because it does not do what its name (and doc) suggest.
> Obviously it wouldn't cost anything and I still think might be useful.
It costs to overcomplicate API for only a half support.
If you need the feature "attach to raw", please implement it completely.
next prev parent reply other threads:[~2016-05-17 14:19 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-15 15:50 [dpdk-dev] [PATCH] " Hiroyuki Mikita
2016-05-16 0:05 ` Ananyev, Konstantin
2016-05-16 2:46 ` Hiroyuki MIKITA
2016-05-16 8:49 ` Ananyev, Konstantin
2016-05-16 9:13 ` Thomas Monjalon
2016-05-16 16:24 ` Hiroyuki MIKITA
2016-05-16 8:52 ` Olivier Matz
2016-05-16 16:53 ` [dpdk-dev] [PATCH v2] " Hiroyuki Mikita
2016-05-17 10:58 ` Bruce Richardson
2016-05-17 11:06 ` Ananyev, Konstantin
2016-05-17 12:43 ` Thomas Monjalon
2016-05-17 12:59 ` Ananyev, Konstantin
2016-05-17 13:39 ` Thomas Monjalon
2016-05-17 13:44 ` Ananyev, Konstantin
2016-05-17 14:19 ` Thomas Monjalon [this message]
2016-05-17 15:45 ` Ananyev, Konstantin
2016-05-17 16:12 ` Hiroyuki MIKITA
2016-05-17 16:35 ` [dpdk-dev] [PATCH v3] " Hiroyuki Mikita
2016-05-18 11:58 ` Olivier Matz
2016-05-18 14:29 ` Hiroyuki Mikita
2016-05-18 14:41 ` [dpdk-dev] [PATCH v4] " Hiroyuki Mikita
2016-05-18 15:51 ` Olivier Matz
2016-05-19 12:38 ` Thomas Monjalon
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