From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
To: Waiman Long <waiman.long@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@linux-foundation.org>,
Richard Weinberger <richard@nod.at>,
Catalin Marinas <catalin.marinas@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Matt Fleming <matt.fleming@intel.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Akinobu Mita <akinobu.mita@gmail.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Michel Lespinasse <walken@google.com>,
Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
George Spelvin <linux@horizon.com>Harvey Harrison <har>
Subject: Re: [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlock implementation
Date: Fri, 02 Aug 2013 08:30:32 +0530 [thread overview]
Message-ID: <51FB20D0.5070306@linux.vnet.ibm.com> (raw)
In-Reply-To: <51FACE78.9070901@hp.com>
On 08/02/2013 02:39 AM, Waiman Long wrote:
> On 08/01/2013 04:23 PM, Raghavendra K T wrote:
>> On 08/01/2013 08:07 AM, Waiman Long wrote:
[..]
>>
>> Though I could see some gains in overcommit, but it hurted undercommit
>> in some workloads :(.
>
> The gcc 4.4.7 compiler that I used in my test machine has the tendency
> of allocating stack space for variables instead of using registers when
> a loop is present. So I try to avoid having loop in the fast path. Also
> the count itself is rather arbitrary. For the first pass, I would like
> to make thing simple. We can always enhance it once it is accepted and
> merged.
Yes. agree.
>>
>> I have not yet tested on bigger machine. I hope that bigger machine will
>> see significant undercommit improvements.
>>
>
> Thank for running the test. I am a bit confused about the terminology.
> What exactly do undercommit and overcommit mean?
>
Undercommit means I meant total #vcpu < #pcpus in virtual env. so
overcommit should not be an issue in baremetal.
WARNING: multiple messages have this Message-ID (diff)
From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
To: Waiman Long <waiman.long@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@linux-foundation.org>,
Richard Weinberger <richard@nod.at>,
Catalin Marinas <catalin.marinas@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Matt Fleming <matt.fleming@intel.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Akinobu Mita <akinobu.mita@gmail.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Michel Lespinasse <walken@google.com>,
Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
George Spelvin <linux@horizon.com>,
Harvey Harrison <harvey.harrison@gmail.com>,
"Chandramouleeswaran, Aswin" <aswin@hp.com>,
"Norton, Scott J" <scott.norton@hp.com>
Subject: Re: [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlock implementation
Date: Fri, 02 Aug 2013 08:30:32 +0530 [thread overview]
Message-ID: <51FB20D0.5070306@linux.vnet.ibm.com> (raw)
Message-ID: <20130802030032.8fhKqEteu0MImYH0k0CykxUsrONDi9431uz-C8m8NT4@z> (raw)
In-Reply-To: <51FACE78.9070901@hp.com>
On 08/02/2013 02:39 AM, Waiman Long wrote:
> On 08/01/2013 04:23 PM, Raghavendra K T wrote:
>> On 08/01/2013 08:07 AM, Waiman Long wrote:
[..]
>>
>> Though I could see some gains in overcommit, but it hurted undercommit
>> in some workloads :(.
>
> The gcc 4.4.7 compiler that I used in my test machine has the tendency
> of allocating stack space for variables instead of using registers when
> a loop is present. So I try to avoid having loop in the fast path. Also
> the count itself is rather arbitrary. For the first pass, I would like
> to make thing simple. We can always enhance it once it is accepted and
> merged.
Yes. agree.
>>
>> I have not yet tested on bigger machine. I hope that bigger machine will
>> see significant undercommit improvements.
>>
>
> Thank for running the test. I am a bit confused about the terminology.
> What exactly do undercommit and overcommit mean?
>
Undercommit means I meant total #vcpu < #pcpus in virtual env. so
overcommit should not be an issue in baremetal.
next prev parent reply other threads:[~2013-08-02 2:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1375324631-32868-1-git-send-email-Waiman.Long@hp.com>
2013-08-01 2:37 ` [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlock implementation Waiman Long
2013-08-01 2:37 ` Waiman Long
[not found] ` <20130801094029.GK3008@twins.programming.kicks-ass.net>
2013-08-01 10:11 ` Raghavendra K T
2013-08-01 10:11 ` Raghavendra K T
2013-08-01 10:12 ` Peter Zijlstra
2013-08-01 10:12 ` Peter Zijlstra
2013-08-01 10:14 ` Peter Zijlstra
2013-08-01 10:14 ` Peter Zijlstra
[not found] ` <51FAA1C3.2050507@hp.com>
2013-08-01 18:16 ` Raghavendra K T
2013-08-01 18:16 ` Raghavendra K T
2013-08-01 20:10 ` Peter Zijlstra
2013-08-01 20:10 ` Peter Zijlstra
2013-08-01 20:36 ` Raghavendra K T
2013-08-01 20:36 ` Raghavendra K T
2013-08-01 20:23 ` Raghavendra K T
2013-08-01 20:23 ` Raghavendra K T
2013-08-01 20:47 ` Peter Zijlstra
2013-08-01 20:47 ` Peter Zijlstra
2013-08-02 2:54 ` Raghavendra K T
2013-08-02 2:54 ` Raghavendra K T
2013-08-01 21:09 ` Waiman Long
2013-08-01 21:09 ` Waiman Long
2013-08-02 3:00 ` Raghavendra K T [this message]
2013-08-02 3:00 ` Raghavendra K T
2013-08-01 2:37 ` [PATCH RFC 2/2] qspinlock x86: Enable x86 to use queue spinlock Waiman Long
2013-08-01 2:37 ` Waiman Long
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