Re: [dpdk-dev] [PATCH v4] build: add meson options of max_memseg_lists and atomic_mbuf_ref_counts

[kefu chai <tchaikov@gmail.com>]

On Mon, Sep 20, 2021 at 4:08 PM Bruce Richardson
<bruce.richardson@intel.com> wrote:
>
> On Mon, Sep 20, 2021 at 03:51:06PM +0800, kefu chai wrote:
> > hello Bruce,
> >
> > do you have any further concerns? is there anything i can do to move
> > this forward?
> >
> > cheers,
> >
>
> +Anatoly, for his input for the memory segments change.
>
> I still would prefer not to have these as config options, but perhaps one
> or both needs to be. The atomic refcount seems more reasonable to add of
> the two. For the max memseg lists, what is the impact if we were to
> increase this value globally?

hi Bruce, thank you for your insights.

yeah, as i explained in the previous email.the atomic refcount is more
critical for my work on integration of DPDK+SPDK+Seastar. since
Seastar enforces share-nothing in its design, there is no need to use
atomic refcount under almost all circumstances. regarding to the max
memseg list, what i am trying is to port the change of
https://github.com/scylladb/seastar/commit/716c7c04db693c266f52de6b0cced0252d70b3bf
to the DPDK used by the latest release of SPDK.

i am copying Avi also for his input. he is the author of the change above.

cheers,

>
> /Bruce
>
> > On Thu, Sep 9, 2021 at 12:51 AM Kefu Chai <tchaikov@gmail.com> wrote:
> > >
> > > RTE_MAX_MEMSEG_LISTS = 128 is not enough for high-memory machines, in our
> > > case, we need to increase it to 8192. so add an option so user can
> > > override it. RTE_MBUF_REFCNT_ATOMIC = 0 is not necessary for applications
> > > like Seastar, where it's safe to assume that the mbuf refcnt is only
> > > updated by a single core only.
> > >
> > > ---
> > >
> > > v4:
> > >
> > > fix the coding style issue by reduce the line length to under 75.
> > > this change should silence the warning like:
> > >
> > > WARNING:COMMIT_LOG_LONG_LINE: Possible unwrapped commit description (prefer a maximum 75 chars per line)
> > > #81:
> > > RTE_MAX_MEMSEG_LISTS = 128 is not enough for high-memory machines, in our case,
> > >
> > > total: 0 errors, 1 warnings, 35 lines checked
> > >
> > > Signed-off-by: Kefu Chai <tchaikov@gmail.com>
> > > ---
> > >  config/meson.build  | 5 ++++-
> > >  config/rte_config.h | 2 --
> > >  meson_options.txt   | 4 ++++
> > >  3 files changed, 8 insertions(+), 3 deletions(-)
> > >
>
> <snip>



-- 
Regards
Kefu Chai