linux-kernel - Re: [PATCH tip/core/rcu 3/4] md/bitmap: Fix list_entry

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Message-ID: <20150924044552.GG4029@linux.vnet.ibm.com>
Date:	Wed, 23 Sep 2015 21:45:53 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Patrick Marlier <patrick.marlier@...il.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>, NeilBrown <neilb@...e.de>,
	linux-kernel@...r.kernel.org, mingo@...nel.org,
	laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
	josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
	dhowells@...hat.com, edumazet@...gle.com, dvhart@...ux.intel.com,
	fweisbec@...il.com, oleg@...hat.com, bobby.prani@...il.com,
	wangyun@...ux.vnet.ibm.com
Subject: Re: [PATCH tip/core/rcu 3/4] md/bitmap: Fix list_entry_rcu usage

On Wed, Sep 23, 2015 at 07:57:53PM +0200, Patrick Marlier wrote:
> 
> On 09/22/2015 10:50 PM, Paul E. McKenney wrote:
> >On Sun, Sep 13, 2015 at 09:10:24AM -0700, Paul E. McKenney wrote:
> >>On Sun, Sep 13, 2015 at 12:06:33PM +0200, Patrick Marlier wrote:
> >
> >[ . . . ]
> >
> >>>Paul,
> >>>
> >>>This sounds good to me. It should fix the performance issue (will
> >>>check with my benchmark).
> >>
> >>Thank you, looking forward to seeing the results!
> >
> >Just following up -- how is the benchmarking going?
> 
> Note that in my module I am using the kernel version 3.16.0-31 (I
> ported your change).
> Here the results of my benchmark that tests rculist in the case of
> read only.
> 
> # 1st column : The number of threads
> # 2nd : ops/s the original version
> # 3rd : ops/s your version with lockless_dereference
> 1 883923 1747554
> 2 1741441 3543062
> 3 2462360 5103647
> 4 3437273 7176608
> 6 5155803 9812348
> 8 6718111 13330050
> 10 8519227 17458294
> 12 9773632 20298897
> 14 11555198 23191424
> 16 11643264 25125712
> 
> I get same performance with my patch.
> So indeed it fixes the performance problem I was seeing.

Nice, thank you!!!

							Thanx, Paul

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