linux-kernel - Re: [RFC PATCH v2] Implement Batched (group) ticket lock

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Date:	Tue, 01 Jul 2014 16:41:06 +0530
From:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	konrad.wilk@...cle.com, pbonzini@...hat.com, gleb@...hat.com,
	paulmck@...ux.vnet.ibm.com, torvalds@...ux-foundation.org,
	waiman.long@...com, riel@...hat.com, davej@...hat.com,
	oleg@...hat.com, x86@...nel.org, jeremy@...p.org,
	paul.gortmaker@...driver.com, ak@...ux.intel.com,
	jasowang@...hat.com, fernando_b1@....ntt.co.jp,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	xen-devel@...ts.xenproject.org, mtosatti@...hat.com,
	chegu_vinod@...com
Subject: Re: [RFC PATCH v2] Implement Batched (group) ticket lock

>>
>> For baremetal we continue to have 'fully fair ticketlock' with this patch
>> series.
>>
>
> But but but, we're looking at removing ticket locks. So why do we want
> to invest in them now?
>

I have nothing against qspinlock. I am happy to test it/add any bit to 
it if I could.

With this patch we get excellent performance for guest with the
unmodified kernel without affecting host.

My test on guest with batch_size =16,32 showed even better performance
               bs=16      bs=32
  ebizzy_0.5x   0.14       0.90
  ebizzy_1.0x   3.57       7.52
  ebizzy_1.5x  58.97      67.65
  ebizzy_2.0x 121.55     136.45




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