-----Original Message-----
From: Nick Connolly <nick.conno...@mayadata.io>
Sent: Monday, November 2, 2020 3:17 AM
To: Khoa To <k...@microsoft.com>; dev@dpdk.org
Subject: Re: [EXTERNAL] [dpdk-dev] [RFC] pthread on Windows
Hi Khoa,
On 29/10/2020 21:19, Khoa To wrote:
-----Original Message-----
From: dev <dev-boun...@dpdk.org> On Behalf Of Nick Connolly
Sent: Monday, October 19, 2020 2:59 AM
To: dev@dpdk.org
Subject: [EXTERNAL] [dpdk-dev] [RFC] pthread on Windows
The proposed changes are:
1. An EAL implementation of pthread with a new rte_pthread API.
2. The DPDK code (libs, examples, drivers, apps, tests, etc) needs to
be modified to use the new rte_pthread API.
3. There needs to be an option for apps to use an external pthread
library as an alternative to the EAL implementation.
4. Eventually, apps can opt in to using the rte_pthread API if desired.
Item #3 isn't dependent on #1 and #2 - it can be implemented now,
allowing forward progress to be made without blocking on #1 and #2
which
may take longer to resolve.
One concern I have with starting on #3 first is that with this patch, we make
pthread semantics mandatory for DPDK core. When new code which
references pthread API is later added to DPDK core, and that functionality
doesn’t yet have a Windows emulation in EAL, DPDK core may take the
dependency on a certain pthread semantics that (a) not implemented
before, and (b) is hard to emulate.
That could represent a problem later, when we introduce the “EAL
threads” API layer with a more loose semantics (which can be backed by
either external pthread library, or by emulation on Windows).
Given that a compile flag is not part of any patch submission that introduces
such new pthread dependency, how do we detect this problem during said
submission?
Do we know if there is a test or submit requirements which ensures that
DPDK compiles on all platforms/environments (including this flag to use
external pthread library) to catch new pthread dependencies, prior to
accepting any new patch?
Khoa.
I think we are ok here ... the patch doesn't change any dependencies, or
make pthreads semantics mandatory for DPDK core. Any changes to DPDK
core will be built and tested against the Windows EAL in exactly the
same way as currently and the same standards of correctness apply. Any
enhancements needed by the DPDK core will need to go into the Windows
EAL as currently. All that the patch does is provide the flexibility to
use an external library to provide part of the functionality of the EAL
if the environment requires it (for example to fit with the
application's threading model).
