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* [dpdk-dev] issue with memory sync on P9
@ 2019-03-18  9:37 Dekel Peled
  2019-03-18  9:37 ` Dekel Peled
  0 siblings, 1 reply; 2+ messages in thread
From: Dekel Peled @ 2019-03-18  9:37 UTC (permalink / raw)
  To: Chao Zhu
  Cc: dev, pradeep, Yongseok Koh, Ori Kam, Thomas Monjalon,
	'David Wilder',
	Shahaf Shuler, Olga Shern

Hi Chao Zhu,

We have recently encountered runtime issues when running DPDK 18.11 (and later) MLX5 PMD on P9 setup.
Using rte_wmb() was found to be insufficient in specific location, memory sync problem occurred regardless.
Using rte_mb() in this specific location fixed the issue.

--- a/drivers/net/mlx5/mlx5_rxtx.h
+++ b/drivers/net/mlx5/mlx5_rxtx.h
@@ -706,7 +706,7 @@ mlx5_tx_dbrec_cond_wmb(struct mlx5_txq_data *txq, volatile struct mlx5_wqe *wqe,
        rte_cio_wmb();
        *txq->qp_db = rte_cpu_to_be_32(txq->wqe_ci);
        /* Ensure ordering between DB record and BF copy. */
-       rte_wmb();
+       rte_mb();
        mlx5_uar_write64_relaxed(*src, dst, txq->uar_lock);
        if (cond)
                rte_wmb();

I see the change in rte_wmb() implementation comes from your patch:
commit d23a6bd04d728226c99d6995c8bd65d49d7e61d1)
Author: Chao Zhu <chaozhu@linux.vnet.ibm.com>
Date:   Fri Jul 15 10:30:19 2016 +0800
eal/ppc: fix memory barrier for IBM POWER

I ran some performance tests and got the same results with and without this patch.
Do you have different findings? Will you approve removing this patch?

Regards,
Dekel

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Chao Zhu
> Sent: Wednesday, February 20, 2019 10:07 AM
> To: Thomas Monjalon <thomas@monjalon.net>; 'David Wilder'
> <dwilder@us.ibm.com>
> Cc: dev@dpdk.org; pradeep@us.ibm.com
> Subject: Re: [dpdk-dev] [dpdk-stable] [PATCH v3] mem: Fix anonymous
> mapping on Power9.
> 
> +Pradeep
> 
> > -----Original Message-----
> > From: Thomas Monjalon <thomas@monjalon.net>
> > Sent: Monday, February 18, 2019 11:47 PM
> > To: David Wilder <dwilder@us.ibm.com>
> > Cc: dev@dpdk.org; chaozhu@linux.vnet.ibm.com
> > Subject: Re: [dpdk-stable] [PATCH v3] mem: Fix anonymous mapping on
> > Power9.
> >
> > Hi,
> >
> > Long time no talk about the IBM Power support status.
> >
> > 16/11/2018 18:35, David Wilder:
> > > --- a/doc/guides/rel_notes/release_18_11.rst
> > > +++ b/doc/guides/rel_notes/release_18_11.rst
> > > +* IBM Power8 is not supported by this release of DPDK. IBM Power9
> > > +is
> > supported.
> >
> > The config file is defconfig_ppc_64-power8-linuxapp-gcc.
> > Given that only Power9 is supported, should we rename it?
> >
> > Is there more changes required to make Power9 working with the latest
> DPDK?
> >
> 
> 

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