Subject: Re: [PATCH net-next v2 1/2] selftests/ptr_ring: add benchmark application for ptr_ring

From: "Michael S. Tsirkin" <[email-masked]>
Date: Sun, 27 Jun 2021 02:09:29 -0400

On Fri, Jun 25, 2021 at 11:52:16AM +0800, Yunsheng Lin wrote:
> On 2021/6/25 11:36, Jason Wang wrote:
> > 
> > 在 2021/6/25 上午11:18, Yunsheng Lin 写道:
> >> Currently ptr_ring selftest is embedded within the virtio
> >> selftest, which involves some specific virtio operation,
> >> such as notifying and kicking.
> >>
> >> As ptr_ring has been used by various subsystems, it deserves
> >> it's owner's selftest in order to benchmark different usecase
> >> of ptr_ring, such as page pool and pfifo_fast qdisc.
> >>
> >> So add a simple application to benchmark ptr_ring performance.
> >> Currently two test mode is supported:
> >> Mode 0: Both enqueuing and dequeuing is done in a single thread,
> >>          it is called simple test mode in the test app.
> >> Mode 1: Enqueuing and dequeuing is done in different thread
> >>          concurrently, also known as SPSC(single-producer/
> >>          single-consumer) test.
> >>
> >> The multi-producer/single-consumer test for pfifo_fast case is
> >> not added yet, which can be added if using CAS atomic operation
> >> to enable lockless multi-producer is proved to be better than
> >> using r->producer_lock.
> >>
> >> Only supported on x86 and arm64 for now.
> >>
> >> Signed-off-by: Yunsheng Lin <[email-masked]>
> >> ---
> >>   MAINTAINERS                                      |   5 +
> >>   tools/testing/selftests/ptr_ring/Makefile        |   6 +
> >>   tools/testing/selftests/ptr_ring/ptr_ring_test.c | 249 +++++++++++++++++++++++
> >>   tools/testing/selftests/ptr_ring/ptr_ring_test.h | 150 ++++++++++++++
> >>   4 files changed, 410 insertions(+)
> > 
> > 
> > Why can't you simply reuse tools/virtio/ringtest?
> 
> The main reason is stated in the commit log:
> "Currently ptr_ring selftest is embedded within the virtio
> selftest, which involves some specific virtio operation,
> such as notifying and kicking.
> 
> As ptr_ring has been used by various subsystems, it deserves
> it's owner's selftest in order to benchmark different usecase
> of ptr_ring, such as page pool and pfifo_fast qdisc."
> 
> More specificly in tools/virtio/ringtest/main.c and
> tools/virtio/ringtest/ptr_ring.c, there are a lot of operation
> related to virtio usecase, such as start_guest(), start_host(),
> poll_used(), notify() or kick() ....., so it makes more sense
> to add a generic selftest for ptr ring as it is not only used
> by virtio now.

Okay that answers why you didn't just run main.c
but why not add a new test under tools/virtio/ringtest/
reusing the rest of infrastructure that you currently copied?

> > Thanks
> > .