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Date:   Mon, 30 Oct 2023 14:05:05 -0400
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Subject: Re: [POC][RFC][PATCH v2] sched: Extended Scheduler Time Slice
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To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
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From:   Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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On 2023-10-30 09:45, Steven Rostedt wrote:
> On Mon, 30 Oct 2023 08:56:50 -0400
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
>>
>> This only works if "your" lock implementation is the only user of this
>> RSEQ feature within a process. RSEQ requires that multiple libraries can
>> share the facilities. Therefore, the rseq field should include the
>> nesting counter as part of the RSEQ ABI so various userspace libraries
>> can use it collaboratively.
>>
> 
> Then I would suggest allowing bit 31 be an "on/off" switch, and the lower
> bits to be a counter. When I first tried this with postgres, there was one
> lwlock that looked to be held for the majority of the run, so I got rid of
> the nesting. But I think a mixture of both would work, where you can have a
> nesting counter and an on/off switch with the caveat that if you use it and
> enable it, another library may disable it.

If you have the nesting counter, why do you need the explicit on/off 
switch ?

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com