Hi Maxime, > -----Original Message----- > From: Maxime Coquelin <[email protected]> > Sent: Wednesday, April 7, 2021 3:48 PM > To: Jiang, Cheng1 <[email protected]>; Xia, Chenbo > <[email protected]>; Thomas Monjalon <[email protected]> > Cc: [email protected]; Hu, Jiayu <[email protected]>; Yang, YvonneX > <[email protected]>; Wang, Yinan <[email protected]>; > [email protected] > Subject: Re: [PATCH] examples/vhost: fix ioat ring space in callbacks > > > > On 3/17/21 6:40 AM, Cheng Jiang wrote: > > We use ioat ring space for determining if ioat callbacks can enqueue a > > packet to ioat device. But there is one slot can't be used in ioat > > ring due to the ioat driver design, so we need to reduce one slot in > > ioat ring to prevent ring size mismatch in ioat callbacks. > > > > Fixes: 2aa47e94bfb2 ("examples/vhost: add ioat ring space count and > check") > > Cc: [email protected] > > > > Signed-off-by: Cheng Jiang <[email protected]> > > --- > > examples/vhost/ioat.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/examples/vhost/ioat.c b/examples/vhost/ioat.c > > index 60b73be93..9cb5e0d50 100644 > > --- a/examples/vhost/ioat.c > > +++ b/examples/vhost/ioat.c > > @@ -113,7 +113,7 @@ open_ioat(const char *value) > > goto out; > > } > > rte_rawdev_start(dev_id); > > - cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE; > > + cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE - 1; > > That really comforts me in thinking we need a generic abstraction for > DMA devices. How is the application developer supposed to know that > the DMA driver has such weird limitations? > > Can the driver be fixed to have a proper behavior?
Here is the patch of providing capacity check API for DMA: http://patches.dpdk.org/project/dpdk/patch/[email protected]/ Thanks, Jiayu > > > dma_info->nr++; > > i++; > > } > >
