Re: [PATCH v3] printk: Add console owner and waiter logic to load balance console writes

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From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	akpm@linux-foundation.org, linux-mm@kvack.org,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@kernel.org>,
	Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	"yuwang.yuwang" <yuwang.yuwang@alibaba-inc.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jan Kara <jack@suse.cz>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Subject: Re: [PATCH v3] printk: Add console owner and waiter logic to load balance console writes
Date: Sat, 4 Nov 2017 12:13:13 +0900	[thread overview]
Message-ID: <20171104031313.GA539@tigerII.localdomain> (raw)
In-Reply-To: <20171102231507.18f6b3b6@vmware.local.home>

On (11/02/17 23:15), Steven Rostedt wrote:
> On Thu, 2 Nov 2017 23:16:16 +0100
> Vlastimil Babka <vbabka@suse.cz> wrote:
> 
> > > +			if (spin) {
> > > +				/* We spin waiting for the owner to release us */
> > > +				spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
> > > +				/* Owner will clear console_waiter on hand off */
> > > +				while (!READ_ONCE(console_waiter))  
> > 
> > This should not be negated, right? We should spin while it's true, not
> > false.
> 
> Ug, yes. How did that not crash in my tests.

Ah, right... Good catch, Vlastimil. The V1 didn't work as expected
on my tests.

	-ss

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WARNING: multiple messages have this Message-ID (diff)

From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	akpm@linux-foundation.org, linux-mm@kvack.org,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@kernel.org>,
	Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	"yuwang.yuwang" <yuwang.yuwang@alibaba-inc.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jan Kara <jack@suse.cz>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Subject: Re: [PATCH v3] printk: Add console owner and waiter logic to load balance console writes
Date: Sat, 4 Nov 2017 12:13:13 +0900	[thread overview]
Message-ID: <20171104031313.GA539@tigerII.localdomain> (raw)
In-Reply-To: <20171102231507.18f6b3b6@vmware.local.home>

On (11/02/17 23:15), Steven Rostedt wrote:
> On Thu, 2 Nov 2017 23:16:16 +0100
> Vlastimil Babka <vbabka@suse.cz> wrote:
> 
> > > +			if (spin) {
> > > +				/* We spin waiting for the owner to release us */
> > > +				spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
> > > +				/* Owner will clear console_waiter on hand off */
> > > +				while (!READ_ONCE(console_waiter))  
> > 
> > This should not be negated, right? We should spin while it's true, not
> > false.
> 
> Ug, yes. How did that not crash in my tests.

Ah, right... Good catch, Vlastimil. The V1 didn't work as expected
on my tests.

	-ss

next prev parent reply	other threads:[~2017-11-04  3:13 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-02 17:45 [PATCH v3] printk: Add console owner and waiter logic to load balance console writes Steven Rostedt
2017-11-02 22:16 ` Vlastimil Babka
2017-11-02 22:16   ` Vlastimil Babka
2017-11-03  3:15   ` Steven Rostedt
2017-11-03  3:15     ` Steven Rostedt
2017-11-04  3:13     ` Sergey Senozhatsky [this message]
2017-11-04  3:13       ` Sergey Senozhatsky
2017-11-03  4:09   ` John Hubbard
2017-11-03 11:21     ` Steven Rostedt
2017-11-03 11:21       ` Steven Rostedt
2017-11-03 11:54       ` Steven Rostedt
2017-11-03 11:54         ` Steven Rostedt
2017-11-03 11:54         ` Steven Rostedt
2017-11-03 11:54           ` Steven Rostedt
2017-11-03 21:46         ` John Hubbard
2017-11-04  3:34           ` John Hubbard
2017-11-04  8:32             ` [PATCH v3] printk: Add console owner and waiter logic to loadbalance " Tetsuo Handa
2017-11-04  8:32               ` Tetsuo Handa
2017-11-04  8:43               ` Tetsuo Handa
2017-11-04  8:43                 ` Tetsuo Handa
2017-11-06 12:06 ` [PATCH v3] printk: Add console owner and waiter logic to load balance " Tetsuo Handa
2017-11-06 12:06   ` Tetsuo Handa
2017-11-07  1:40   ` Sergey Senozhatsky
2017-11-07  1:40     ` Sergey Senozhatsky
2017-11-07 11:05     ` [PATCH v3] printk: Add console owner and waiter logic to loadbalance " Tetsuo Handa
2017-11-07 11:05       ` Tetsuo Handa
2017-11-08  5:19     ` [PATCH v3] printk: Add console owner and waiter logic to load balance " Sergey Senozhatsky
2017-11-08  5:19       ` Sergey Senozhatsky
2017-11-08 14:29       ` Steven Rostedt
2017-11-08 14:29         ` Steven Rostedt
2017-11-09  0:56         ` Sergey Senozhatsky
2017-11-09  0:56           ` Sergey Senozhatsky
2017-11-09  3:29           ` Steven Rostedt
2017-11-09  3:29             ` Steven Rostedt
2017-11-09  4:45             ` Sergey Senozhatsky
2017-11-09  4:45               ` Sergey Senozhatsky
2017-11-09  5:06               ` Steven Rostedt
2017-11-09  5:06                 ` Steven Rostedt
2017-11-09  5:33                 ` Sergey Senozhatsky
2017-11-09  5:33                   ` Sergey Senozhatsky

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