From: Jens Axboe <axboe@kernel.dk>
To: Wander Costa <wcosta@redhat.com>
Cc: Wander Lairson Costa <wander@redhat.com>,
open list <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
"open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH v5 1/1] blktrace: switch trace spinlock to a raw spinlock
Date: Mon, 20 Dec 2021 13:24:52 -0700 [thread overview]
Message-ID: <b07b97b4-dff2-5915-ce56-a039a14a74dd@kernel.dk> (raw)
In-Reply-To: <CAAq0SUn_Nru1NTyzgjB9ETsaM46bgDRf3DTa+Z9sG-c8yjuQdw@mail.gmail.com>
On 12/20/21 12:49 PM, Wander Costa wrote:
> On Mon, Dec 20, 2021 at 4:38 PM Jens Axboe <axboe@kernel.dk> wrote:
>>
>> On 12/20/21 12:28 PM, Wander Lairson Costa wrote:
>>> The running_trace_lock protects running_trace_list and is acquired
>>> within the tracepoint which implies disabled preemption. The spinlock_t
>>> typed lock can not be acquired with disabled preemption on PREEMPT_RT
>>> because it becomes a sleeping lock.
>>> The runtime of the tracepoint depends on the number of entries in
>>> running_trace_list and has no limit. The blk-tracer is considered debug
>>> code and higher latencies here are okay.
>>
>> You didn't put a changelog in here. Was this one actually compiled? Was
>> it runtime tested?
>
> It feels like the changelog reached the inboxes after patch (at least
> mine was so). Would you like that I send a v6 in the hope things
> arrive in order?
Not sure how you are sending them, but they don't appear to thread
properly. But the changelog in the cover letter isn't really a
changelog, it doesn't say what changed.
--
Jens Axboe
next prev parent reply other threads:[~2021-12-20 20:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 19:28 [PATCH v5 1/1] blktrace: switch trace spinlock to a raw spinlock Wander Lairson Costa
2021-12-20 19:38 ` Jens Axboe
2021-12-20 19:49 ` Wander Costa
2021-12-20 20:24 ` Jens Axboe [this message]
2021-12-20 20:34 ` Wander Costa
2021-12-20 20:37 ` Jens Axboe
2021-12-20 20:43 ` Wander Costa
2021-12-20 20:49 ` Jens Axboe
2021-12-20 23:30 ` Steven Rostedt
2021-12-20 23:45 ` Jens Axboe
2021-12-20 20:50 ` Jens Axboe
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