Received-SPF: pass (google.com: domain of linux-kernel+bounces-79454-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Message-ID: <cd56eb4e-520e-4ab2-a041-0a580cb42e1e@amd.com>
Date: Sat, 24 Feb 2024 08:45:06 +0530
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 00/30] PREEMPT_AUTO: support lazy rescheduling
Content-Language: en-US
From: Raghavendra K T <raghavendra.kt@amd.com>
To: Ankur Arora <ankur.a.arora@oracle.com>,
 Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
 torvalds@linux-foundation.org, paulmck@kernel.org,
 akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de,
 dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com,
 juri.lelli@redhat.com, vincent.guittot@linaro.org, willy@infradead.org,
 mgorman@suse.de, jpoimboe@kernel.org, mark.rutland@arm.com, jgross@suse.com,
 andrew.cooper3@citrix.com, bristot@kernel.org,
 mathieu.desnoyers@efficios.com, geert@linux-m68k.org,
 glaubitz@physik.fu-berlin.de, anton.ivanov@cambridgegreys.com,
 mattst88@gmail.com, krypton@ulrich-teichert.org, rostedt@goodmis.org,
 David.Laight@ACULAB.COM, richard@nod.at, mjguzik@gmail.com,
 jon.grimm@amd.com, bharata@amd.com, boris.ostrovsky@oracle.com,
 konrad.wilk@oracle.com
References: <20240213055554.1802415-1-ankur.a.arora@oracle.com>
 <15fcf98c-58c5-fa08-2e21-f3b0baf058e6@amd.com> <87zfvtg2mh.ffs@tglx>
 <f1a5fe09-f4bc-0dc5-edda-6b3e690bc0e3@amd.com> <87ttm0dwhk.ffs@tglx>
 <87bk87c1n7.fsf@oracle.com> <f32b90fe-2d56-4e9e-8f44-c7ee662af43d@amd.com>
In-Reply-To: <f32b90fe-2d56-4e9e-8f44-c7ee662af43d@amd.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?utf-8?B?cm1ELzdiQlV3VllUWDQ3cVJpYkpBbXdMTW1zbEpMWHZNZGZaNHc5d0xlc3Z1?=
 =?utf-8?B?V29wZ1RUcHpoQkNrL2M1bjI3WjhLMlhQNDEyTDUvUi9udjJVTC83ODN2MHpN?=
 =?utf-8?B?Zk13L0JtbHhyTHFKSEsrUlZaVUNJaHhRb1JHVnB0SkVSa3UxSFJZTDBBVmxE?=
 =?utf-8?B?cUQzSzdHbk92YTEyMjBGdGJDVXdkYXpZckZXeW9KSVUwREYxUTV4M0JXelFk?=
 =?utf-8?B?NWg1ZERzenl2aEF5UHltRWQvZDJDcVhqZElxVUNWUGlRaDR2d0c3NnY5TzRy?=
 =?utf-8?B?Q2o0aGt0c0R0MEJnU0YwYWlZZnBCQWk2eFY1RFNWaFZEa0FrTGsvUjN4dW1B?=
 =?utf-8?B?ODhtVDVMQzN4djhqMXQ3ZDhScE5QMmlrWmpUcXZjTGpFRmUvM3J1UWxqbm9G?=
 =?utf-8?B?VDhxa1FRTFZnbExxNnBhUkU1TlhBeGZJZ3EvZkwwdjFwbFhGZ2FGK1lPWEVJ?=
 =?utf-8?B?ZHBjcWRQdVBCeXFYeFlhOXRYN3B6VnZhanJCb3J5b05sR212aHpTT3JrTHlG?=
 =?utf-8?B?NzVqRjFKSEYzQUZPSDNEb3FUYnJGaWpXM2M0dXluNTdUbmxJTVV2Y1VGS1NW?=
 =?utf-8?B?Ry95NFNObUxxcnpvN0t4Tk5MRVk2UGNBNUpQT25pTUJFR3g5TU1ERVdXbEtI?=
 =?utf-8?B?VGRleUVkanN5bXcvTjNDWEJXY0l5M0dPbDRBVWRzVzRxbWhyZXNWV2YvUThl?=
 =?utf-8?B?U2EveEJRWksxMTllUm9COHdSbVd0TU04Zk1oM1ZSK29CWU9ReW5uNlo2Uk9X?=
 =?utf-8?B?d2lLTjluUFE0eFVOWWtVandNcGp6TDFWZlh4di9jVFVhNHlyUU1NTDF1NHZs?=
 =?utf-8?B?NmZibEhKSmpFbXlFMnF5REdWSTBxcXdqczNlNnF2Zm5kWmQvUVhFdWc1Q3dH?=
 =?utf-8?B?WXJ5ZWd5TmpwMWVBcXlUZUFRS2dQNk9RTG5CdzZqVklCWTRaMjVOQkVnL3VQ?=
 =?utf-8?B?MERFYTlpdXpmQVVzOG5NQXR0YjkrUk5OOWY5SHYxeExPQlJvVVRnRlhTOGVG?=
 =?utf-8?B?eDgrd3hiRXhsZXljN2FZWTRhd3J3MWR4bGZVSkw2K2pSYkUrM1RZQ0NiUEUr?=
 =?utf-8?B?aEhSVjRsMktwd1Z6S1dKRy9MMzR1T2VpdEZEeFlCZHdQTUhMTTkwVStRT2tt?=
 =?utf-8?B?cEwwRGFNeXFoSjJxWENWSHI2UjhobUhTS3FwTmtRbTdRYXBUd0QxUWR1RDJm?=
 =?utf-8?B?UmZvT1A4YXNubG4wdlBKT0pGRHJwNzV3bVJqRGdLMEkrS0JWUDhHaFZzaDdq?=
 =?utf-8?B?aERUdVgyMHcwd256UGVKL0JRVS83SjVYMXhUUHNFQzEyTk4rZ2syZldwTWZi?=
 =?utf-8?B?VDlsV1VIcnhlcHNBZHZDbVl3NlArbk1xUllaTERTcnhPMk5iWnptS09aT0dX?=
 =?utf-8?B?M1FhbjFBVHF6aWw3UHk1RzB4QXRRbktTRzdtZ21LVTFzMGF4Qlc4NHYzVksr?=
 =?utf-8?B?RDV5YytaZy90d2ZlZXREb2VaL3prSHl6V0ZqU3BRQUlMaGtBVkh2ZXJoMExq?=
 =?utf-8?B?YlBoUjVQOWQ1RytObEFsdktJeDg3WFN1YjJ0NlRSd2VRWUhIdXdaVDhJdStU?=
 =?utf-8?B?MmRzWW01SkpTdWkxWmF6MFRyTFVnU3JzNVdseVZMQ3V0SldRY2p3cDJPME5Q?=
 =?utf-8?B?a0RzWHBHVEdmUVRVb3NRL2JScEE2bXlFejJESEh0OHRYc1lyNTFQUUU1V1FN?=
 =?utf-8?B?UnJDSFZ6cUZoeDQ0QzZoLzk2VVc4YlVxWVJuNXBVcGJSZWJYV2tjdXQybkwv?=
 =?utf-8?B?UXlreWRCa21IZEM3WkRQdTU1c1JiVHRyWUxVK2UzbjFHYTQ2NkNldEJtMldY?=
 =?utf-8?B?ZUJUNGh1cHgvcFZtZ0M3ZmNPeHM0ZnpURE9ubStDUkVscngwK0dPZ2FoMGFQ?=
 =?utf-8?B?N0VFVXNXSjJlUDA4WEV1dTR4THQrbEFnRmRRVWRad1VIVDdxUE1oYnhBcVkv?=
 =?utf-8?B?c3hpanVQZGZ0cG5JaUcxR2xNbHlzckRmR3N3WStsMDZDUVFxR3p2NE9YMFdT?=
 =?utf-8?B?NjhJcS9JeHBiM1o1NjNzb3hLTzdmNTh2OWIyS2tYWWdpcFp4dFRuSEJDUHh6?=
 =?utf-8?B?R0thb0NtRk9zRG9jMFBWT1ZZZFF4Y0graVJZQVZQRTFnUTZYWnV5c2w5Wi81?=
 =?utf-8?Q?FlR9qiansc0aOQ7NNHDcWbQ0W?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 8accebbc-d32e-42a0-8488-08dc34e6d5fd
X-MS-Exchange-CrossTenant-AuthSource: PH7PR12MB5805.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Feb 2024 03:15:22.0554
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: BZj3MDsRtySUNwNlXQUQgZS90xytpgi342LxApnbGOYAWS3FQorZpzqOk9BI2Ub9OL1G+Eqaat0Sj/L3LRH0jQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR12MB4558

On 2/23/2024 11:58 AM, Raghavendra K T wrote:
> On 2/23/2024 8:44 AM, Ankur Arora wrote:
>>
>> Thomas Gleixner <tglx@linutronix.de> writes:
>>
>>> On Wed, Feb 21 2024 at 22:57, Raghavendra K T wrote:
>>>> On 2/21/2024 10:45 PM, Thomas Gleixner wrote:
>>>>> On Wed, Feb 21 2024 at 17:53, Raghavendra K T wrote:
>>>>>> Configuration tested.
>>>>>> a) Base kernel (6.7),
>>>>>
>>>>> Which scheduling model is the baseline using?
>>>>>
>>>>
>>>> baseline is also PREEMPT_DYNAMIC with voluntary preemption
>>>>
>>>>>> b) patched with PREEMPT_AUTO voluntary preemption.
>>>>>> c) patched with PREEMPT_DYNAMIC voluntary preemption.
>>>
>>> Which RCU variant do you have enabled with a, b, c ?
>>>
>>> I.e. PREEMPT_RCU=?
>>
>> Raghu please confirm this, but if the defaults were chosen
>> then we should have:
>>
>>>> baseline is also PREEMPT_DYNAMIC with voluntary preemption
>> PREEMPT_RCU=y
>>
>>>>>> b) patched with PREEMPT_AUTO voluntary preemption.
>>
>> If this was built with PREEMPT_VOLUNTARY then, PREEMPT_RCU=n.
>> If with CONFIG_PREEMPT, PREEMPT_RCU=y.
>>
>> Might be worth rerunning the tests with the other combination
>> as well (still with voluntary preemption).
>>
>>>>>> c) patched with PREEMPT_DYNAMIC voluntary preemption.
>> PREEMPT_RCU=y
> 
> Hello Thomas, Ankur,
> Yes, Ankur's understanding is right, defaults were chosen all the time so
> for
> a) base 6.7.0+ + PREEMPT_DYNAMIC with voluntary preemption PREEMPT_RCU=y
> b) patched + PREEMPT_AUTO voluntary preemption. PREEMPT_RCU = n
> c) patched + PREEMPT_DYNAMIC with voluntary preemption PREEMPT_RCU=y

> I will check with other combination (CONFIG_PREEMPT/PREEMPT_RCU) for (b)
> and comeback if I see anything interesting.
> 

I see that

d) patched + PREEMPT_AUTO=y voluntary preemption CONFIG_PREEMPT, 
PREEMPT_RCU = y

All the results at 80% confidence
		case (d)
HashJoin         0%
Graph500         0%
XSBench          +1.2%
NAS-ft           +2.1%

In general averages are better for all the benchmarks but at 99%
confidence there seem to be no difference.

Overall looks on par or better for case (d)

Thanks and Regards
- Raghu