RE: [PATCH v7] net/bonding: another fix to LACP mempool size

[Matan Azrad <matan@nvidia.com>]

Hi Ferruh, Gaoxiang

From: Ferruh Yigit
> On 3/28/2022 4:16 PM, Gaoxiang Liu wrote:
> > The following log message may appear after a slave is idle(or nearly
> > idle)
> > for a few minutes:"PMD: Failed to allocate LACP packet from pool".
> > And bond mode 4 negotiation may fail.
> >
> > Problem:When bond mode 4 has been chosed and delicated queue has not
> > been enable, all mbufs from a slave' private pool(used exclusively for
> > transmitting LACPDUs) have been allocated in interrupt thread, and are
> > still sitting in the device's tx descriptor ring and other cores'
> > mempool caches in fwd thread.
> > Thus the interrupt thread can not alloc LACP packet from pool.
> >
> > Solution: Ensure that each slave'tx (LACPDU) mempool owns more than
> > n-tx-queues * n-tx-descriptor + fwd_core_num *
> > per-core-mmempool-flush-threshold mbufs.
> >
> > Note that the LACP tx machine fuction is the only code that allocates
> > from a slave's private pool. It runs in the context of the interrupt
> > thread, and thus it has no mempool cache of its own.
> >
> > Signed-off-by: Gaoxiang Liu <liugaoxiang@huawei.com>
> >
> > ---
> > v2:
> > * Fixed compile issues.
> >
> > v3:
> > * delete duplicate code.
> >
> > v4;
> > * Fixed some issues.
> > 1. total_tx_desc should use +=
> > 2. add detailed logs
> >
> > v5:
> > * Fixed some issues.
> > 1. move CACHE_FLUSHTHRESH_MULTIPLIER to rte_eth_bond-8023ad.c 2.
> use
> > RTE_MIN
> >
> > v6:
> > * add a comment of CACHE_FLUSHTHRESH_MULTIPLIER macro
> >
> > v7:
> > * Fixed some issues.
> > 1. move CACHE_FLUSHTHRESH_MULTIPLIER to rte_mempool.h
> > ---
> >   drivers/net/bonding/rte_eth_bond_8023ad.c | 7 ++++---
> >   lib/mempool/rte_mempool.h                 | 2 ++
> >   2 files changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/bonding/rte_eth_bond_8023ad.c
> > b/drivers/net/bonding/rte_eth_bond_8023ad.c
> > index ca50583d62..f7f6828126 100644
> > --- a/drivers/net/bonding/rte_eth_bond_8023ad.c
> > +++ b/drivers/net/bonding/rte_eth_bond_8023ad.c
> > @@ -1050,6 +1050,7 @@ bond_mode_8023ad_activate_slave(struct
> rte_eth_dev *bond_dev,
> >       uint32_t total_tx_desc;
> >       struct bond_tx_queue *bd_tx_q;
> >       uint16_t q_id;
> > +     uint32_t cache_size;
> >
> >       /* Given slave mus not be in active list */
> >       RTE_ASSERT(find_slave_by_id(internals->active_slaves,
> > @@ -1100,11 +1101,11 @@ bond_mode_8023ad_activate_slave(struct
> rte_eth_dev *bond_dev,
> >               total_tx_desc += bd_tx_q->nb_tx_desc;
> >       }
> >
> > +     cache_size = RTE_MIN(RTE_MEMPOOL_CACHE_MAX_SIZE, 32);
> > +     total_tx_desc += rte_lcore_count() * cache_size *
> > + RTE_MEMPOOL_CACHE_FLUSHTHRESH_MULTIPLIER;
> >       snprintf(mem_name, RTE_DIM(mem_name), "slave_port%u_pool",
> slave_id);
> >       port->mbuf_pool = rte_pktmbuf_pool_create(mem_name,
> total_tx_desc,
> > -             RTE_MEMPOOL_CACHE_MAX_SIZE >= 32 ?
> > -                     32 : RTE_MEMPOOL_CACHE_MAX_SIZE,
> > -             0, element_size, socket_id);
> > +             cache_size, 0, element_size, socket_id);
> >
> >       /* Any memory allocation failure in initialization is critical because
> >        * resources can't be free, so reinitialization is impossible.
> > */ diff --git a/lib/mempool/rte_mempool.h
> b/lib/mempool/rte_mempool.h
> > index 1e7a3c1527..fa15ed710f 100644
> > --- a/lib/mempool/rte_mempool.h
> > +++ b/lib/mempool/rte_mempool.h
> > @@ -56,6 +56,8 @@
> >   extern "C" {
> >   #endif
> >
> > +#define RTE_MEMPOOL_CACHE_FLUSHTHRESH_MULTIPLIER 1.5
> > +
> 
> This change seems already get some comments and changes in previous
> versions.
> 
> I also thought why we are adding a new macro to the mempool for a bonding
> driver update, but that is not the whole picture.
> There is an existing 'CACHE_FLUSHTHRESH_MULTIPLIER' macro in mempool,
> this patch wants to use it but that macro is not exposed.
> And I can see there is other user of that macros (mlx5_rxq.c [1]) suffering
> from same problem.
> 
> So, what do you think having two patches,
> - first one is only for mempool update, which removes the
> 'CACHE_FLUSHTHRESH_MULTIPLIER' from 'rte_mempool.c', adds
> 'RTE_MEMPOOL_CACHE_FLUSHTHRESH_MULTIPLIER' to 'rte_mempool.h' as
> this patch does, and update existing usage.
> 
> - second patch just updates the bonding driver and use the new
> 'RTE_MEMPOOL_CACHE_FLUSHTHRESH_MULTIPLIER' macro
> 
> 
> 
> [1] @Matan, @Slava,
> 'mlx5_rxq.c', comment mentions that it intends to use
> 'CACHE_FLUSHTHRESH_MULTIPLIER' but can't access it and use a hardcoded
> value (2). But the hard coded value and macro values doesn't match, is it
> intentional.

I think it is to pass the cache size check into mempool API.


> When 'RTE_MEMPOOL_CACHE_FLUSHTHRESH_MULTIPLIER' is exposed in
> header, can it be replaced with hard coded value in the driver?

Yes, we need to be careful with the types when doing the calculation to ensure it will continue to pass the mempool check.
For sure, we can help and validate here.

Matan



> 
> 
> 
> >   #define RTE_MEMPOOL_HEADER_COOKIE1  0xbadbadbadadd2e55ULL
> /**< Header cookie. */
> >   #define RTE_MEMPOOL_HEADER_COOKIE2  0xf2eef2eedadd2e55ULL
> /**< Header cookie. */
> >   #define RTE_MEMPOOL_TRAILER_COOKIE  0xadd2e55badbadbadULL
> /**<
> > Trailer cookie.*/