Re: [PATCH v4 5/5] blktrace: Make init_blk_tracer() asynchronous when trace_async_init set

[Yaxiong Tian]

在 2026/1/30 17:30, Masami Hiramatsu (Google) 写道:
> On Thu, 29 Jan 2026 15:29:58 -0500
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> > On Wed, 28 Jan 2026 19:25:46 -0700
> > Jens Axboe <axboe@xxxxxxxxx> wrote:
> >
> > > On Jan 28, 2026, at 5:40 PM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> > > > 
> > > > Jens,
> > > >
> > > > Can you give me an acked-by on this patch and I can take the series through
> > > > my tree.
> > > On phone, hope this works:
> > >
> > > Acked-by: Jens Axboe <axboe@xxxxxxxxx>
> > Thanks!
> >
> > > > Or perhaps this doesn't even need to test the trace_async_init flag and can
> > > > always do the work queue? Does blk_trace ever do tracing at boot up? That
> > > > is, before user space starts?
> > > Not via the traditonal way of running blktrace.
> > Masami and Yaxiong,
> >
> > I've been thinking about this more and I'm not sure we need the
> > trace_async_init kernel parameter at all. As blktrace should only be
> > enabled by user space, it can always use the work queue.
> >
> > For kprobes, if someone is adding a kprobe on the kernel command line, then
> > they are already specifying that tracing is more important.
> >
> > Patch 3 already keeps kprobes from being an issue with contention of the
> > tracing locks, so I don't think it ever needs to use the work queue.
> >
> > Wouldn't it just be better to remove the trace_async_init and make blktrace
> > always use the work queue and kprobes never do it (but exit out early if
> > there were no kprobes registered)?
> Yeah, for kprobes event case, that sounds good to me. I think [3/5] is
> enough to speed it up if user does not define kprobe events on cmdline.
>
> Thank you,

Agreed.

Hi Jens：

 what do you think about this proposal (making blktrace always use the 
work queue)?

> > That is, remove patch 2 and 4 and make this patch always use the work queue.
> >
> > -- Steve