Re: [dpdk-dev] [PATCH v1] app/crypto-perf: set mbuf lengths correctly for DOCSIS tests

[Akhil Goyal <akhil.goyal@nxp.com>]

> Hi Pablo/David,
> >
> > Hi David,
> >
> > > Hi Pablo,
> > >
> > > > -----Original Message-----
> > > > From: De Lara Guarch, Pablo <pablo.de.lara.guarch@intel.com>
> > > > Sent: Friday, July 17, 2020 8:04 PM
> > > > > @@ -48,6 +48,10 @@ cperf_set_ops_security(struct rte_crypto_op
> **ops,
> > > > >  			} else
> > > > >  				buf_sz = options->test_buffer_size;
> > > > >
> > > > > +			sym_op->m_src->buf_len = options-
> >segment_sz;
> > > > > +			sym_op->m_src->data_len = buf_sz;
> > > > > +			sym_op->m_src->pkt_len = buf_sz;
> > > > > +
> > > >
> > > > Actually, I am wondering why this is needed at all (for DOCSIS and
> > > > PDCP). This is already set in " fill_multi_seg_mbuf" or "
> > > > fill_single_seg_mbuf" (and this was already working without this patch,
> > right?).
> > >
> > > [DC] I have found that if a number of buffer sizes are specified like this on
> the
> > > cmd line "--buffer-sz 64,256,1024", then the pkt_len and data_len filled in
> > > "fill_multi_seg_mbuf" or " fill_single_seg_mbuf" is always the largest of the
> > sizes
> > > specified. The cipher/auth lengths are then set based on the --buffer-sz
> option.
> > >
> > > For DOCSIS, I tried to be more accurate and set the correct pkt_len and
> > data_len
> > > in the mbuf. This followed what PDCP did too, even though I'm not sure of
> the
> > > background why PDCP did it - possibly spotted the same issue. I have also
> > found
> > > that DOCSIS performance figures can be better if the correct pkt_len and
> > > data_len are set in the mbuf - I don't have any proper explanation for this
> > > though as the cipher/ auth lengths are always the same.
> > >
> > > I've dug around a bit more on this now though and this is actually a problem
> > > across the perf tool. Some of the crypto PMDs have logic based on the mbuf
> > > pkt_len and data_len, but because the perf tool isn't always setting these
> fields
> > > correctly, that logic may not work as expected.
> > > >
> >
> > Right, thanks for checking this. If I remember correctly, it was fine to have this
> > set to the maximum size as the important field for crypto PMDs to check is the
> > cipher/auth lengths, as you said. If there is more logic that depends on
> data_len
> > on other PMDs, I agree it might be a problem. The only usage I knew for it was
> > the multi segment case (in AES-GCM PMD), where data_len is checked in each
> > segment size to see if all the cipher/auth length resides within these segments,
> > but in the tool we set data_len for each segment when "going multi-segment".
> I
> > see that other PMDs like DPAA2_SEC use these fields for something which I am
> > not sure what's for. It would be good if the maintainers check if this is a
> problem
> > for them, and in that case, this should be fixed for the other functions (for
> > "normal" crypto).
> >
> 
> In case of test-crypto-perf, the buffers are flat and there is no case of multi
> segment.
> So this is not because of that.
> In case of PDCP and probably all the protocol offload cases would need the
> buf_len/
> data_len/pkt_len to be set properly. As the complete buffer is given to hardware
> and depending on the headers added, HW/PMD will adjust these lengths when
> the
> packet is dequeued, provided it has room available to expand.
> 
> We may not need this in cases of pure crypto which have fixed lengths and PMD
> does
> not control them.
> 
> So in my opinion this patch is fine.
> 
> Acked-by: Akhil Goyal <akhil.goyal@nxp.com>
> 
> 
This patch was applied yesterday to dpdk-next-crypto
And is now pulled to master as well.