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Date: Tue, 5 Mar 2024 13:02:25 -0800
From: Tyler Retzlaff <roretzla@linux.microsoft.com>
To: Mattias =?iso-8859-1?Q?R=F6nnblom?= <hofors@lysator.liu.se>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: RTE lock
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On Tue, Mar 05, 2024 at 09:18:20PM +0100, Mattias Rönnblom wrote:
> Shouldn't we have a DPDK-native mutex API, rather than using direct
> POSIX mutex lock calls?

David raised this a while back and the consensus is yes. I admit it's
been on my radar for a long time for the obvious reasons you list below
but with other work hasn't been a priority (yet).

> 
> There are two reasons for this, as I see it
> 1) more cleanly support non-POSIX operating system (i.e., Microsoft
> Windows).
> 2) to discourage mechanical use of spinlocks in places where a
> regular mutex lock is more appropriate.
> 
> I think (and hope) DPDK developers will tend to pick DPDK-native
> rather than other APIs as their first choice.

I spent some time evaluating C11 mutex but it really didn't strike me as
being fit for purpose so I think DPDK-native is probably the only way to
go. If behind the scenes particular locks relied on something standard
for Windows perhaps it could be hidden as an implementation detail.

> 
> For locks, they go for spinlocks, even in control (non-fast
> path/non-packet processing) code paths (e.g., calls made by the
> typical non-EAL thread).
> 
> Using spinlocks to synchronize threads that may be preempted aren't
> great idea.

If you're thinking of looking into this i'd be happy to see it solved.

ty