From: "Morten Brørup" <mb@smartsharesystems.com>
To: "David Marchand" <david.marchand@redhat.com>,
"Stephen Hemminger" <stephen@networkplumber.org>
Cc: <dev@dpdk.org>, <konstantin.v.ananyev@yandex.ru>
Subject: RE: [PATCH] dumpcap: fix mbuf pool ring type
Date: Mon, 2 Oct 2023 10:42:53 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35D87C27@smartserver.smartshare.dk> (raw)
In-Reply-To: <CAJFAV8yktcK4DZXCYeLnsJ==tEWvD3y=uS9rZFZX=HjZHdEvnQ@mail.gmail.com>
> From: David Marchand [mailto:david.marchand@redhat.com]
> Sent: Monday, 2 October 2023 09.34
>
> On Fri, Aug 4, 2023 at 6:16 PM Stephen Hemminger
> <stephen@networkplumber.org> wrote:
> >
> > The ring used to store mbufs needs to be multiple producer,
> > multiple consumer because multiple queues might on multiple
> > cores might be allocating and same time (consume) and in
> > case of ring full, the mbufs will be returned (multiple producer).
>
> I think I get the idea, but can you rephrase please?
>
>
> >
> > Bugzilla ID: 1271
> > Fixes: cb2440fd77af ("dumpcap: fix mbuf pool ring type")
>
> This Fixes: tag looks wrong.
>
>
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > ---
> > app/dumpcap/main.c | 7 +++----
> > 1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/app/dumpcap/main.c b/app/dumpcap/main.c
> > index 64294bbfb3e6..991174e95022 100644
> > --- a/app/dumpcap/main.c
> > +++ b/app/dumpcap/main.c
> > @@ -691,10 +691,9 @@ static struct rte_mempool *create_mempool(void)
> > data_size = mbuf_size;
> > }
> >
> > - mp = rte_pktmbuf_pool_create_by_ops(pool_name, num_mbufs,
> > - MBUF_POOL_CACHE_SIZE, 0,
> > - data_size,
> > - rte_socket_id(), "ring_mp_sc");
> > + mp = rte_pktmbuf_pool_create(pool_name, num_mbufs,
> > + MBUF_POOL_CACHE_SIZE, 0,
> > + data_size, rte_socket_id());
>
> Switching to rte_pktmbuf_pool_create() still leaves the user with the
> possibility to shoot himself in the foot (I was thinking of setting
> some --mbuf-pool-ops-name EAL option).
>
> This application has explicit requirements in terms of concurrent
> access (and I don't think the mempool library exposes per driver
> capabilities in that regard).
> The application was enforcing the use of mempool/ring so far.
>
> I think it is safer to go with an explicit
> rte_pktmbuf_pool_create_by_ops(... "ring_mp_mc").
> WDYT?
<feature creep>
Or perhaps one of "ring_mt_rts" or "ring_mt_hts", if any of those mbuf pool drivers are specified on the command line; otherwise fall back to "ring_mp_mc".
Actually, I prefer Stephen's suggestion of using the default mbuf pool driver. The option is there for a reason.
However, David is right: We want to prevent the user from using a thread-unsafe mempool driver in this use case.
And I guess there might be other use cases than this one, where a thread-safe mempool driver is required. So adding a generalized function to get the "upgraded" (i.e. thread safe) variant of a mempool driver would be nice.
</feature creep>
Feel free to ignore my suggested feature creep, and go ahead with David's suggestion instead.
>
>
> > if (mp == NULL)
> > rte_exit(EXIT_FAILURE,
> > "Mempool (%s) creation failed: %s\n", pool_name,
> > --
> > 2.39.2
> >
>
> Thanks.
>
> --
> David Marchand
next prev parent reply other threads:[~2023-10-02 8:42 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-04 16:16 Stephen Hemminger
2023-08-05 9:05 ` Morten Brørup
2023-10-02 7:33 ` David Marchand
2023-10-02 8:42 ` Morten Brørup [this message]
2023-11-06 19:23 ` Stephen Hemminger
2023-11-06 21:50 ` Morten Brørup
2023-11-07 2:36 ` Stephen Hemminger
2023-11-07 7:22 ` Morten Brørup
2023-11-07 16:41 ` Stephen Hemminger
2023-11-07 17:38 ` Morten Brørup
2023-11-08 16:50 ` Stephen Hemminger
2023-11-08 17:43 ` Morten Brørup
2023-11-07 17:00 ` Stephen Hemminger
2023-11-06 19:24 ` Stephen Hemminger
2023-11-06 19:34 ` [PATCH v2] " Stephen Hemminger
2023-11-08 17:47 ` [PATCH v3 ] " Stephen Hemminger
2023-11-09 7:21 ` Morten Brørup
2023-11-12 14:05 ` Thomas Monjalon
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