linux-kernel - Re: [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlock implementation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Fri, 02 Aug 2013 08:30:32 +0530
From:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To:	Waiman Long <waiman.long@...com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Arnd Bergmann <arnd@...db.de>,
	linux-arch@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Richard Weinberger <richard@....at>,
	Catalin Marinas <catalin.marinas@....com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Akinobu Mita <akinobu.mita@...il.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Michel Lespinasse <walken@...gle.com>,
	Andi Kleen <andi@...stfloor.org>,
	Rik van Riel <riel@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	George Spelvin <linux@...izon.com>,
	Harvey Harrison <harvey.harrison@...il.com>,
	"Chandramouleeswaran, Aswin" <aswin@...com>,
	"Norton, Scott J" <scott.norton@...com>
Subject: Re: [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlock
 implementation

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.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/