Re: [PATCH 1/3] net/hns3: fix simple Tx path incorrect free the mbuf

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 8 Jan 2025 10:40:43 +0800
Jie Hai <haijie1@huawei.com> wrote:

> On 2024/12/31 1:55, Stephen Hemminger wrote:
> > On Mon, 30 Dec 2024 14:54:03 +0800
> > Jie Hai <haijie1@huawei.com> wrote:
> >   
> >> From: Jie Hai <haijie1@huawei.com>
> >> To: <dev@dpdk.org>, <thomas@monjalon.net>, <ferruh.yigit@amd.com>,  <david.marchand@redhat.com>, <andrew.rybchenko@oktetlabs.ru>, Chengwen Feng  <fengchengwen@huawei.com>, "Wei Hu (Xavier)" <xavier.huwei@huawei.com>,  Huisong Li <lihuisong@huawei.com>
> >> CC: <haijie1@huawei.com>, <huangdengdui@huawei.com>
> >> Subject: [PATCH 1/3] net/hns3: fix simple Tx path incorrect free the mbuf
> >> Date: Mon, 30 Dec 2024 14:54:03 +0800
> >> X-Mailer: git-send-email 2.22.0
> >>
> >> From: Dengdui Huang <huangdengdui@huawei.com>
> >>
> >> When RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE offload is not set,
> >> use rte_pktmbuf_free_seg() to free the mbuf.
> >>
> >> Fixes: 7ef933908f04 ("net/hns3: add simple Tx path")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Dengdui Huang <huangdengdui@huawei.com>
> >> Signed-off-by: Jie Hai <haijie1@huawei.com>  
> > 
> > What about the fast free case which is using rte_mempool_put_bulk when
> > it should use rte_pktmbuf_free_bulk instead?
> > 
> >   
> Hi, Stephen Hemminger,
> 
> During the fast free case, the performance of using
> rte_mempool_put_bulk is higher than that of using
> rte_pktmbuf_free_bulk because other references
> to mbuf do not need to be considered. So it's better
>   to not change.
> 
> Thanks,
> Jie Hai

The problem is that having an open coded version of this buried in
one driver is a long term potential problem.

If you really think that optimizing free like this is noticeable, then
why not make a new function "rte_pktmuf_fast_free_bulk" and put it in the
regular mbuf library.