From: "H. Peter Anvin" <hpa@zytor.com>
To: Mike Galbraith <bitbucket@online.de>
Cc: Andi Kleen <andi@firstfloor.org>,
linux-kernel@vger.kernel.org, x86@kernel.org, mingo@kernel.org,
torvalds@linux-foundation.org
Subject: Re: Re-tune x86 uaccess code for PREEMPT_VOLUNTARY
Date: Sat, 10 Aug 2013 21:27:26 -0700 [thread overview]
Message-ID: <520712AE.6060904@zytor.com> (raw)
In-Reply-To: <1376194657.7006.11.camel@marge.simpson.net>
On 08/10/2013 09:17 PM, Mike Galbraith wrote:
>>
>> Do you have any quantification of "munches throughput?" It seems odd
>> that it would be worse than polling for preempt all over the kernel, but
>> perhaps the additional locking is what costs.
>
> I hadn't compared in ages, so made some fresh samples.
>
> Q6600 3.11-rc4
>
> vmark
> voluntary 169808 155826 154741 1.000
> preempt 149354 124016 128436 .836
>
> That should be ~worst case, it hates preemption.
>
> tbench 8
> voluntary 1027.96 1028.76 1044.60 1.000
> preempt 929.06 935.01 928.64 .900
>
> hackbench -l 10000
> voluntary 23.146 23.124 23.230 1.000
> preempt 25.065 24.633 24.789 1.071
>
> kbuild vmlinux
> voluntary 3m44.842s 3m42.975s 3m42.954s 1.000
> preempt 3m46.141s 3m45.835s 3m45.953s 1.010
>
> Compute load comparisons are boring 'course.
>
I presume voluntary is indistinguishable from no preemption at all?
Either way, that is definitely a reproducible test case, so if someone
is willing to take on optimizing preemption they can use vmark as the
litmus test. It would be really awesome if we genuinely could get the
cost of preemption down to where it just doesn't matter.
-hpa
next prev parent reply other threads:[~2013-08-11 4:28 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-09 23:04 Re-tune x86 uaccess code for PREEMPT_VOLUNTARY Andi Kleen
2013-08-09 23:04 ` [PATCH 01/13] x86: Add 1/2/4/8 byte optimization to 64bit __copy_{from,to}_user_inatomic Andi Kleen
2013-08-09 23:04 ` [PATCH 02/13] x86: Include linux/sched.h in asm/uaccess.h Andi Kleen
2013-08-09 23:04 ` [PATCH 03/13] tree-sweep: Include linux/sched.h for might_sleep users Andi Kleen
2013-08-09 23:04 ` [PATCH 04/13] Move might_sleep and friends from kernel.h to sched.h Andi Kleen
2013-08-09 23:04 ` [PATCH 05/13] sched: mark should_resched() __always_inline Andi Kleen
2013-08-09 23:04 ` [PATCH 06/13] x86: Add 32bit versions of SAVE_ALL/RESTORE_ALL to calling.h Andi Kleen
2013-08-09 23:04 ` [PATCH 07/13] Add might_fault_debug_only() Andi Kleen
2013-08-14 18:24 ` Michael S. Tsirkin
2013-08-09 23:04 ` [PATCH 08/13] x86: Move cond_resched into the out of line put_user code Andi Kleen
2013-08-09 23:04 ` [PATCH 09/13] x86: Move cond_resched into the out of line get_user code Andi Kleen
2013-08-09 23:04 ` [PATCH 10/13] x86: Move cond resched for copy_{from,to}_user into low level code 64bit Andi Kleen
2013-08-10 15:42 ` Linus Torvalds
2013-08-10 16:10 ` Andi Kleen
2013-08-10 16:27 ` Linus Torvalds
2013-08-10 18:23 ` Borislav Petkov
2013-08-10 19:05 ` Jörn Engel
2013-08-20 21:03 ` KOSAKI Motohiro
2013-08-15 5:04 ` Michael S. Tsirkin
2013-08-09 23:04 ` [PATCH 11/13] sched: Inline the need_resched test into the caller for _cond_resched Andi Kleen
2013-08-09 23:04 ` [PATCH 12/13] x86: move __copy_*_nocache might fault check out of line Andi Kleen
2013-08-09 23:04 ` [PATCH 13/13] x86: drop cond rescheds from __copy_{from,to}_user Andi Kleen
2013-08-10 4:42 ` Re-tune x86 uaccess code for PREEMPT_VOLUNTARY H. Peter Anvin
2013-08-10 5:55 ` Mike Galbraith
2013-08-10 16:09 ` H. Peter Anvin
2013-08-10 16:43 ` Linus Torvalds
2013-08-10 17:18 ` H. Peter Anvin
2013-08-10 18:51 ` Linus Torvalds
2013-08-10 19:18 ` H. Peter Anvin
2013-08-10 20:26 ` H. Peter Anvin
2013-08-10 23:00 ` H. Peter Anvin
2013-08-11 4:17 ` Mike Galbraith
2013-08-11 4:27 ` H. Peter Anvin [this message]
2013-08-11 4:36 ` Mike Galbraith
2013-08-11 4:57 ` H. Peter Anvin
2013-08-11 5:58 ` Mike Galbraith
2013-08-13 18:09 ` H. Peter Anvin
2013-08-13 18:12 ` Andi Kleen
2013-08-14 18:27 ` Michael S. Tsirkin
2013-08-14 22:08 ` Andi Kleen
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