From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out162-62-58-216.mail.qq.com (out162-62-58-216.mail.qq.com [162.62.58.216]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E4D2711714 for ; Fri, 23 Feb 2024 05:17:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=162.62.58.216 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708665481; cv=none; b=A7V/fQfY7WB2WvXDTvUbeds3f6rl9uVzLxTHS0XCqJWuAdtFnBdhwjbkk1uWVe2hX+IvyF7EAE3sIociFZQX78y7lM6lEG6XZeuZCyJRs2J5ikJFLtEgDOpDC7zQXb5RYakeYU6iUf/pAd7xKNcoqXwpYB3OGUSpuI/IY2WQLe4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708665481; c=relaxed/simple; bh=X/W5DwQO7kT7FYswAnD6pfP/r7ijSZmYe1K+mAC1F3g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qLDrczYW7JrM2v8bZr2pyLV1iRkuCcD+Jp1hsng55bTbwLzVPx46d3vCji3XoTz9cECGZQDKUQN6pN1lJ0xy+sx0k5c1X0GlTxVLADUtvWI+NbFZgDECSgcm1M/QlezB7QL7v66v8zEw73F8bHqqsYhv/nRzndVgo/dT9z2VyOs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=foxmail.com; spf=pass smtp.mailfrom=foxmail.com; dkim=pass (1024-bit key) header.d=foxmail.com header.i=@foxmail.com header.b=bNtK8dMH; arc=none smtp.client-ip=162.62.58.216 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=foxmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=foxmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=foxmail.com header.i=@foxmail.com header.b="bNtK8dMH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foxmail.com; s=s201512; t=1708665474; bh=7BRUNUShwwd1gbD7m9jCq76qqkjH47dO+405L2MFVRA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=bNtK8dMHNaXcKCTyoO7tQhbCTNJyzuSHUkjYup3CG4erhViR/Y6RJOUqMvxCtnPZR dxwBo1fn+8CcaX6kIp74+/rpT5Ekj5Ah/v0bLFFwxTFvzWVgQwpCmgWPfOiB2sM0S5 3lOvwRiexXE+6ChQ2Hax0E+NYJVDfEtPW62dbHnE= Received: from [IPV6:2409:8961:2a00:95cb:ea24:ca0f:4466:39d5] ([2409:8961:2a00:95cb:ea24:ca0f:4466:39d5]) by newxmesmtplogicsvrsza10-0.qq.com (NewEsmtp) with SMTP id 4731E03F; Fri, 23 Feb 2024 13:17:51 +0800 X-QQ-mid: xmsmtpt1708665471ta754ocoi Message-ID: X-QQ-XMAILINFO: NyTsQ4JOu2J2nQUV7WtK8TK7JidjFHCKiemiGG1RIe+Sce/bIdazkayQW/jwVt 0esl/eyHmqiuP9zpuflDaPwEeEVtqHDvLHjyefZiNAeVy53ZhaYqA2P/FEWRjQSBa2/iPZrM1ffY pJq3uUMG82q899oZtEWtGbarmLgXcKT1vf0Fh+vNCPHegm17mRw4VGuffXNMuwanHDes70Fxu+ZF 9P6h/3elX3h4CAdXHuZL0N6plFOsVn0BlXejPbkFq7PMegOMDjByRfXq08Lo/ymmO5/gsCxvNpEJ tuWvAFcArQg506f4qBb6s+DLglc2YDDve2j1BMl/RGIosqhGI90lt3WK47iwrtA6UITrvPe8+0NB F0L40+BbARcMRD7Zz+bUvUaZDtQyXQWg9X8XRYrJRtraIWZvGfPXsIx5dZxXnRJVP+UStXYM/8L0 MQh7b8SCGju1iasYL87rAgGeCSAAq2yoMWRkn9I1yc1JRk9dkpcqi7KHkUrflLFSwfrPnzGfPz0T JAtg8LK2uu7SPZ62P7Pdj/hTnXCE82ldu3cE6Wpx3OuJRq/0AwIO/yW51tU3B+Pqg2ySoZWNRf7a +jHd5whRLc796u59oGF79Abr9lqzTOI7g+ZujBw9gznMBogP6u/sOwc0umXzs9luiXKRMElRsazJ 7H3YTT6DdScJlWqKhfEecn2etI7JLjGk7ar0ib9GcUcbHsys8F4yEYahLfShk/pGByGkXy3ELy+g VuBrNBwwfzt+wjTVcG04fgSxeu9NqfWhi+HqPT307nI6P498GQsZ8yxF4aQOp6w9khfJ5IiPhcNq ovwE/dCjfW8NynyowNQR4Km4VQQJYqkDafUsEeAVEEXP4FXSO6tM7I4OeNqOV20//7N7qXSDvA4w r6nEkS7shmsA5/uJtvwcnfkInMkT/Z8y/sEf94Kv2TBWwvWdx8nMIUbOpBFuwldCgIaxRP9mfP5O FeFghsVoPZwF43YuzJHWGUIVHE5535HKCMkxYHuNU3jNZlYbethyjr08wzPStARaKD559KbtjF75 ZjVTA8CENmv5cEWMJtmUnhVK5ovpttSaFhEfjzXu87hTB6eB+k X-QQ-XMRINFO: MSVp+SPm3vtS1Vd6Y4Mggwc= X-OQ-MSGID: Date: Fri, 23 Feb 2024 13:17:50 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH 1/2] exit: add a tracepoint for profiling a task that is starting to exit Content-Language: en-US To: Mathieu Desnoyers , Steven Rostedt , Masami Hiramatsu , Ingo Molnar Cc: Oleg Nesterov , Mel Gorman , Peter Zijlstra , linux-kernel@vger.kernel.org References: From: Wen Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/2/23 00:25, Mathieu Desnoyers wrote: > On 2024-02-22 11:04, wenyang.linux@foxmail.com wrote: >> From: Wen Yang >> >> Currently coredump_task_exit() takes some time to wait for the generation >> of the dump file. But if the user-space wants to receive a notification >> as soon as possible it maybe inconvenient. >> >> Commit 2d4bcf886e42 ("exit: Remove profile_task_exit & profile_munmap") >> simplified the code, but also removed profile_task_exit(), which may >> prevent third-party kernel modules from detecting process exits timely. >> >> Add the new trace_sched_profile_task_exit() this way a user-space monitor >> could detect the exits and potentially make some preparations in advance. > > I don't see any explanation justifying adding an extra tracepoint > rather than just moving trace_sched_process_exit() earlier in do_exit(). > > Why is moving trace_sched_process_exit() earlier in do_exit() an issue, > considering that any tracer interested in knowing the point where a task > is really reclaimed (from zombie state) is trace_sched_process_free() > called from delayed_put_task_struct() ? > > Thanks, > > Mathieu > Thanks. We will make the modifications according to your suggestions. -- Best wishes, Wen >> >> Signed-off-by: Wen Yang >> Cc: Oleg Nesterov >> Cc: Steven Rostedt >> Cc: Masami Hiramatsu >> Cc: Mathieu Desnoyers >> Cc: Ingo Molnar >> Cc: Mel Gorman >> Cc: Peter Zijlstra >> Cc: linux-kernel@vger.kernel.org >> --- >>   include/trace/events/sched.h | 28 ++++++++++++++++++++++++++++ >>   kernel/exit.c                |  1 + >>   2 files changed, 29 insertions(+) >> >> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h >> index dbb01b4b7451..750b2f0bdf69 100644 >> --- a/include/trace/events/sched.h >> +++ b/include/trace/events/sched.h >> @@ -341,6 +341,34 @@ DEFINE_EVENT(sched_process_template, >> sched_wait_task, >>       TP_PROTO(struct task_struct *p), >>       TP_ARGS(p)); >> +/* >> + * Tracepoint for profiling a task that is starting to exit: >> + */ >> +TRACE_EVENT(sched_profile_task_exit, >> + >> +    TP_PROTO(struct task_struct *task, long code), >> + >> +    TP_ARGS(task, code), >> + >> +    TP_STRUCT__entry( >> +        __array(    char,    comm,    TASK_COMM_LEN    ) >> +        __field(    pid_t,    pid            ) >> +        __field(    int,    prio            ) >> +        __field(    long,    code            ) >> +    ), >> + >> +    TP_fast_assign( >> +        memcpy(__entry->comm, task->comm, TASK_COMM_LEN); >> +        __entry->pid        = task->pid; >> +        __entry->prio        = task->prio; >> +        __entry->code        = code; >> +    ), >> + >> +    TP_printk("comm=%s pid=%d prio=%d exit_code=0x%lx", >> +          __entry->comm, __entry->pid, __entry->prio, >> +          __entry->code) >> +); >> + >>   /* >>    * Tracepoint for a waiting task: >>    */ >> diff --git a/kernel/exit.c b/kernel/exit.c >> index 493647fd7c07..f675f879a1b2 100644 >> --- a/kernel/exit.c >> +++ b/kernel/exit.c >> @@ -826,6 +826,7 @@ void __noreturn do_exit(long code) >>       WARN_ON(tsk->plug); >> +    trace_sched_profile_task_exit(tsk, code); >>       kcov_task_exit(tsk); >>       kmsan_task_exit(tsk); >