> -----Original Message----- > From: Ananyev, Konstantin <konstantin.anan...@intel.com> > Sent: Wednesday, September 11, 2019 16:35 > To: Ruifeng Wang (Arm Technology China) <ruifeng.w...@arm.com>; > Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>; Kantecki, Tomasz > <tomasz.kante...@intel.com> > Cc: dev@dpdk.org; Gavin Hu (Arm Technology China) <gavin...@arm.com>; > nd <n...@arm.com>; nd <n...@arm.com>; nd <n...@arm.com> > Subject: RE: [dpdk-dev] [PATCH 0/2] add lock-free mode for l3fwd > > > > > -----Original Message----- > > From: Ruifeng Wang (Arm Technology China) > > [mailto:ruifeng.w...@arm.com] > > Sent: Wednesday, September 11, 2019 7:58 AM > > To: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>; Ananyev, > > Konstantin <konstantin.anan...@intel.com>; Kantecki, Tomasz > > <tomasz.kante...@intel.com> > > Cc: dev@dpdk.org; Gavin Hu (Arm Technology China) > <gavin...@arm.com>; > > nd <n...@arm.com>; nd <n...@arm.com>; nd <n...@arm.com> > > Subject: RE: [dpdk-dev] [PATCH 0/2] add lock-free mode for l3fwd > > > > > -----Original Message----- > > > From: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com> > > > Sent: Wednesday, September 11, 2019 13:38 > > > To: Ruifeng Wang (Arm Technology China) <ruifeng.w...@arm.com>; > > > Ananyev, Konstantin <konstantin.anan...@intel.com>; Kantecki, > Tomasz > > > <tomasz.kante...@intel.com> > > > Cc: dev@dpdk.org; Gavin Hu (Arm Technology China) > > > <gavin...@arm.com>; Honnappa Nagarahalli > > > <honnappa.nagaraha...@arm.com>; nd <n...@arm.com>; nd > <n...@arm.com> > > > Subject: RE: [dpdk-dev] [PATCH 0/2] add lock-free mode for l3fwd > > > > > > <snip> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Lock-free mode is supported by hash library and LPM library. > > > > > > > > Now we add an option for l3fwd example to enable the > > > > > > > > lock-free > > > > mode. > > > > > > > > Necessary preparation steps are added to use lock-free LPM > mode. > > > > > > > > > > > > > > Can I ask about the purpose of these changes? > > > > > > > Right now in l3fwd both lpm and hash tables are static and > > > > > > > hard- > > > coded. > > > > > > > we initialize them at startup and then just do read from them. > > > > > > > Do you plan to enhance l3fwd with ability to dynamically > > > > > > > update tables contents? > > > > > > > Though fir that we first have to get rid of hard-coded > > > > > > > values (config file or > > > > > so). > > > > > > > Konstantin > > > > > > > > > > > > > Thanks for your questions. > > > > > > Currently, we have no plan to enhance l3fwd with ability to > > > > > > dynamically > > > > > update table contents. > > > > > > Lock-free method is being integrated into Hash library and LPM > > > > > > library. Lock-free algorithms are not only about control > > > > > > plane (adding or deleting routes), they affect the data path > > > > > > performance as > > > well. > > > > > > Since l3fwd application is showcasing data path performance, > > > > > > we need to show the impact of including the quiescent state > > > > > > reporting on data > > > > path. > > > > > > This change also serves as an example of using the RCU APIs. > > > > > > > > > > > > > > > But what you suggest doesn't provide the complete picture. > > > > > With dynamic updates in place (via control path) the data-path > > > > > impact might be completely different then without. > > > > > Again without dynamic updates how can you test that your > > > > > data-path > > > > > lock- free approach does work as expected? > > > > > Also it can't even be used as a reference implementation for > > > > > users, as half of the functionality they need to implement is simply > missing. > > > > > My opinion - we either need to leave l3fwd as it is (static > > > > > routes), or implement a proper control path with ability to > > > > > dynamically update routes before starting to introduce some > > > > > synchronization schemes (RCU or whatever). > > > > > > > > > > Konstantin > > > > > > > > > > > > > Agree that dynamic control path updates should be included for a > > > > whole picture. > > > > I will add dynamic update to l3fwd and reroll the patch series. > > > > Thanks. > > > I think we should have an agreement on what exactly we mean by > > > 'dynamically update routes'. > > > IMO, we should not disturb the existing static routes as there might > > > be automated tests running in the labs. I suggest that we should > > > add/delete new routes/hash entries which are different from the > > > existing routes/hash entries. This should be sufficient to showcase > > > the functionality as well as measure the impact. > > > > > Yes, existing static routes should be kept intact. > > To perform regular route/hash entries add/delete, a dedicated lcore will be > needed. > > An interactive prompt is not an option since we need automatic add/delete. > > We can skip master core for data path main loop. And perform unrelated > route/hash entries add/delete regularly on master core. > > The impact is that command lines used in tests will need update since > master core will no longer do data path work. > > Not sure why it has to be master core? > Why interrupt thread wouldn't do? > I think what we need to: > 1. introduce reading routes from config file instead of having them hard- > coded within the app. > 2. add ability to update routes dynamically. > Probably the easiest (and commonly used way) re-read conf file and > update routes on the signal (SIGUSR1 or so). > Konstantin > > Sorry for delayed response. Just back from vacation. Thanks for your suggestion. I will try the config file based updating approach and get back with new version.
> > > > > > > > > > > > > > > > > > > > > > > > > > Patch 2/2 has dependency on RCU QSBR integration with LPM > > > library: > > > > > > > > http://patches.dpdk.org/project/dpdk/list/?series=6288 > > > > > > > > > > > > > > > > > > > > > > > > Ruifeng Wang (2): > > > > > > > > examples/l3fwd: add lock-free option for l3fwd > > > > > > > > examples/l3fwd: integrate RCU QSBR for LPM mode > > > > > > > > > > > > > > > > doc/guides/sample_app_ug/l3_forward.rst | 3 ++ > > > > > > > > examples/l3fwd/Makefile | 1 + > > > > > > > > examples/l3fwd/l3fwd.h | 4 +- > > > > > > > > examples/l3fwd/l3fwd_em.c | 10 +++- > > > > > > > > examples/l3fwd/l3fwd_lpm.c | 72 > > > > > +++++++++++++++++++++++-- > > > > > > > > examples/l3fwd/main.c | 27 ++++++++-- > > > > > > > > examples/l3fwd/meson.build | 1 + > > > > > > > > 7 files changed, 108 insertions(+), 10 deletions(-) > > > > > > > > > > > > > > > > -- > > > > > > > > 2.17.1 > > > > > > >
