Re: [PATCH] trace/pid_list: optimize pid_list->lock contention

[Steven Rostedt]

On Wed, 12 Nov 2025 13:27:10 +0800
Yongliang Gao <leonylgao@xxxxxxxxx> wrote:

> Thank you for your detailed response and the proposed RCU-like approach.
> 
> I've looked into using a regular seqlock instead of the current
> implementation, but as you pointed out, the write side is indeed a
> critical path. More importantly, I found that even with seqlock, the
> write_seqlock() function internally uses spin_lock() which on
> PREEMPT_RT gets converted to an mutex. This would cause the same
> issues we're trying to avoid - potential sleep in atomic contexts.

I believe there is a raw_read_seqcount() functionality that is safe for
PREEMPT_RT. Have you looked into using that?

-- Steve