[dpdk-dev] [PATCH v1 0/3] relax io barrier for aarch64 and use smp barriers for virtual pci memory
Gavin Hu (Arm Technology China)
Gavin.Hu at arm.com
Thu Nov 7 02:13:43 CET 2019
Hi Maxime,
> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin at redhat.com>
> Sent: Wednesday, October 23, 2019 4:23 PM
> To: Gavin Hu (Arm Technology China) <Gavin.Hu at arm.com>; dev at dpdk.org
> Cc: nd <nd at arm.com>; david.marchand at redhat.com; tiwei.bie at intel.com;
> thomas at monjalon.net; rasland at mellanox.com; matan at mellanox.com;
> shahafs at mellanox.com; viacheslavo at mellanox.com;
> arybchenko at solarflare.com; stephen at networkplumber.org;
> hemant.agrawal at nxp.com; jerinj at marvell.com;
> pbhagavatula at marvell.com; Honnappa Nagarahalli
> <Honnappa.Nagarahalli at arm.com>; Ruifeng Wang (Arm Technology China)
> <Ruifeng.Wang at arm.com>; Phil Yang (Arm Technology China)
> <Phil.Yang at arm.com>; Joyce Kong (Arm Technology China)
> <Joyce.Kong at arm.com>; Steve Capper <Steve.Capper at arm.com>
> Subject: Re: [PATCH v1 0/3] relax io barrier for aarch64 and use smp barriers
> for virtual pci memory
>
> Hi Gavin,
>
> On 10/22/19 5:27 PM, Gavin Hu wrote:
> > Armv8's peripheral coherence order is a total order on all reads and
> > writes to that peripheral, that makes a compiler barrier is enough for
> > abstracted rte io barrier.
> >
> > For virtual PCI devices, the virtual device memory is actually normal
> > memory and the Hypervisor view of things takes precedence and they are
> > within a smp configuration and smp barriers should be used, the
> > relaxed io barrier for aarch64 becomes insufficient.
>
> IIUC, this series is for performance optimization and not fixing
> coherency issues. Can you confirm?
Yes, this is for perf optimization.
>
> If that's the case, I'm afraid we'll have to postpone it to v20.02,
> our patch queues are already too big at that stage of the release.
Ok, no problem, thanks!
>
> Maxime
>
> > Gavin Hu (3):
> > eal/arm64: relax the io barrier for aarch64
> > net/virtio: virtual PCI requires smp barriers
> > crypto/virtio: virtual PCI requires smp barriers
> >
> > drivers/crypto/virtio/virtio_pci.c | 124 ++++++++++++++++-----
> > drivers/net/virtio/virtio_pci.c | 124 ++++++++++++++++-----
> > .../common/include/arch/arm/rte_atomic_64.h | 6 +-
> > 3 files changed, 191 insertions(+), 63 deletions(-)
> >
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