[dpdk-dev] [PATCH] net/mlx5: revert mbuf address calculation for x86

[Shahaf Shuler]

Thursday, March 28, 2019 12:21 AM, Yongseok Koh:
>
> Cc: dev <dev at dpdk.org>; dpdk stable <stable at dpdk.org>; Kevin Traynor
> <ktraynor at redhat.com>
> Subject: Re: [dpdk-dev] [PATCH] net/mlx5: revert mbuf address calculation
> for x86
> 
> 
> > On Mar 27, 2019, at 4:51 AM, Kevin Traynor <ktraynor at redhat.com>
> wrote:
> >
> > On 25/03/2019 19:13, Yongseok Koh wrote:
> >> When replenishing mbufs on Rx, buffer address (mbuf->buf_addr) should
> >> be loaded. non-x86 processors (mostly RISC such as ARM and Power) are
> >> more vulnerable to load stall. For x86, reducing the number of
> >> instructions seems to matter most.
> >>
> >> For x86, this is simply a load but for other architectures, it is
> >> calculated from the address of mbuf structure by rte_mbuf_buf_addr()
> >> without having to load the first cacheline of the mbuf.
> >>
> >
> > Hi Yongseok,
> >
> >> Fixes: 12d468a62bc1 ("net/mlx5: fix instruction hotspot on
> >> replenishing Rx buffer")
> >
> > A similar backport was just added into 18.11.1-RC2, should it be
> > reverted? I'm not keen to put another fix for it in for 18.11.1 at
> > this stage, I think it can be part of 18.11.2. WDYT?
> 
> I spoke with Kevin and we decided to drop the old fix.
> I have also dropped it from 17.11.6-rc1.
> 
> This new fix will be merged to 18.11.2.
> I'll merge it to 17.11.6 (or 17.11.7) if it is merged in the master.

Applied to next-net-mlx, thanks.