Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7;
Message-ID: <0bfc5c56-467e-40ef-b0ee-0a15d7f64e33@intel.com>
Date:   Mon, 20 Nov 2023 08:34:41 -0700
User-Agent: Betterbird (Linux)
Subject: Re: [PATCH 09/34] dmaengine: idxd: optimize perfmon_assign_event()
To:     Yury Norov <yury.norov@gmail.com>, <linux-kernel@vger.kernel.org>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Vinod Koul <vkoul@kernel.org>, <dmaengine@vger.kernel.org>
CC:     Jan Kara <jack@suse.cz>,
        Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>,
        Matthew Wilcox <willy@infradead.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>,
        Alexey Klimov <klimov.linux@gmail.com>,
        "Fenghua Yu" <fenghua.yu@intel.com>,
        "tom.zanussi@linux.intel.com" <tom.zanussi@linux.intel.com>
References: <20231118155105.25678-1-yury.norov@gmail.com>
 <20231118155105.25678-10-yury.norov@gmail.com>
Content-Language: en-US
From:   Dave Jiang <dave.jiang@intel.com>
In-Reply-To: <20231118155105.25678-10-yury.norov@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?b29CNmtRNkZzOW1WL3UxR0VTL2hkbk9DY3pKOUYwMkd2aDBnMkk1S0JDaUxE?=
 =?utf-8?B?VDlGVVJHSTR6S3U0OUxrOUpYY3owZWh1NituSVhBKzJFbldiazdYMzRQR0JE?=
 =?utf-8?B?dnlmY2xCdXh6bTBPU3hqMHZYK3ZiODdnYmgvSTFTR1l0ZVN2U21DSVNoMTA3?=
 =?utf-8?B?WlJGZzdTLy9zMkl6RDQ0QklpUE9rLzhCYTcvTnlReXVjMUp6ZW0ycklSSWhY?=
 =?utf-8?B?TERUSmhSRU5nczZKVzJBUC9kbzZsMnhndk9wd3o4aWwwQUFBQWxqTjd1bXox?=
 =?utf-8?B?ZWt2L0J5NHJVdjdpNXlCeTM3dCtjTHQ3aFNuZG1VOE9qZ3VmdnFFK1UwUDRD?=
 =?utf-8?B?M3BvbVNyNXZOM3k5akFBbVF2Z0crTkNIVDZsWi9wZXBqZ0FhR0RpU241OEZ6?=
 =?utf-8?B?RHF5LzAyUlV6UVovNnJtOEZRN3dlVEVkUFRGT3E5c3RVWFpJanRkbWFZMzZv?=
 =?utf-8?B?VEFtVE1mRzlRc3hhbkxUOWYxY1BMRUFFWWRsTmhycndGbFdJTE9qZHlOdW02?=
 =?utf-8?B?MmNPeVJzMHZSWTdjS0tNZWlkRXJxZDYva0VneFVXSXJmRy9iZUt2MjFWRHN5?=
 =?utf-8?B?UVFPS1FkbzJidk9jdHplSDdob1hyWlJvMVpjNExRVnhNNDlidmhFZ1hNekt4?=
 =?utf-8?B?Vm9uRi9mU24rOEJYMXRoTXBRaE5mUnYyMCt2NzFmSlNLYUdRd1I0SU43eEM1?=
 =?utf-8?B?a0xZOXllOGd2eUUyaTNaMnN0VWNMNU03c3RvaVJiOXl1Z1R1Wk0yRk1GMmxa?=
 =?utf-8?B?d1BJdlhDSTRlTDFNVnZYcXlNc1prUTJlc0FrR1REbTA2bDU1bkttUXF3S25z?=
 =?utf-8?B?Mit6ZU9wWnRTa0lKM1IzblpJeWx1UThBY0wrbFczNHBCcldDYzZTWTJhTjlP?=
 =?utf-8?B?MWp1a0RwbW5NSjkyYVExVXk3Mk1KKzVMQU9tdWx0MnV0RjZZb2pjaG93dFNI?=
 =?utf-8?B?UHNweWoxMm45OUtoWWpmVzdiR3FvME9wWGlBZVRuQm94dWRJNFpuditmRDZE?=
 =?utf-8?B?Tmx0WEVhYjEvME9EUkcvRnExOE41VWtZQUdSbE0wb0NzNzRyY3FnMGV5L0lt?=
 =?utf-8?B?aUhTUm8rVERxQ3UzM2taVGltOWp4aDZHbmRSczB0OC9vR0FSb21nd3NYK0hX?=
 =?utf-8?B?emRuZ2NtSnBHVFNFUXcwclk3bjFBQ3RKaVVaYnBSMWlaeUdhc1pNN1R3cE8r?=
 =?utf-8?B?cWpZbmN3bnB1VmNJekE1SDJNU2FUWmlZaktPK3VPUjloYWtOVmpzWm84RVVs?=
 =?utf-8?B?V2RQNlpWTEZMcGl5bEFUb1VFSlJZZFM0WVdJUGZiRG92d3hvaEFuc1lOUFRs?=
 =?utf-8?B?dmNDb0Z0RHg0QTZZaHdjcnArOGVZNVcvRG5NdWgvVW5NbWx4ZXpNbXc5b3BO?=
 =?utf-8?B?ak02RzBjTEErcTRPaUIrS09OQjBMcDk4QWFzbUROSWhNZ2sxY0RHN21sNkxl?=
 =?utf-8?B?Mkl2QmQ4dkhxcFdYb2tpeHdxRFFnaE5jbmJoYlBXTkk1bVJFK3JzOWRoZis1?=
 =?utf-8?B?N2FtbXJGdThWU2VmUElpSXRadkdReFQ3RlMzS1BnNGJUZmdwU3JpdTBDVzlQ?=
 =?utf-8?B?SzZ5S2F6V1cwSnR4L1YreHdHU3FPa3VDZEU5N1NHeitLSTFuNEVlWFZkczI0?=
 =?utf-8?B?TXAxZUlHeE9zWXIvWlFxaXg3S01ZaDBLdUpOTWlZN3VvcTltK3d2a01STzV3?=
 =?utf-8?B?VlFYK2JBYWptWHdDR01FR1dkTmVCUklSNnJtalk2S0hRbHB0empLeFJraC9M?=
 =?utf-8?B?NVorSzRxbjVnbnVoMHJ6K2k4T0F6ZHJ4enlqWXptbFE2emErZ0dZaXpTR3N2?=
 =?utf-8?B?Z2w3RE5pUHl3TlV4VW5PaDdtMmJXZnA1UXcwTHI5WDI1QldkU1N4amNRQXR6?=
 =?utf-8?B?VERjM05ZY2lpSkhHVFJQWWNTRVZMMFQ4L2I1eG95NnNmck4zd2dzV29mNlNB?=
 =?utf-8?B?WWJtUzNMb0poT2l6K0k1bGJpa0kvZVdmVTc2cFB2bjd3K3ZyOGNLdVdjQkZB?=
 =?utf-8?B?RjV0RE90aFluakQ1UWczVjZTWnJlRUxucytzcEwzUGE0RnBqSmFRanI5R0hY?=
 =?utf-8?B?Y1gvUDF5a3RQdkpOdkIxUGowU254YnE1OGRXeUVwK25WUU1FUkRiV3BYcG11?=
 =?utf-8?Q?/1+3oNf3S7fYHRSvHocAjpPFQ?=
X-MS-Exchange-CrossTenant-Network-Message-Id: f79cfcd2-98e0-4f29-70ea-08dbe9de3864
X-MS-Exchange-CrossTenant-AuthSource: PH7PR11MB5984.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Nov 2023 15:34:44.3099
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: N3vodUW6W+Ss6G3PwLWsSS5koE5/rCufTOpH7hAFV377ezWhzBZkhpY+D/v/HemW6SA8b9FOjS+tcugHUY8J1g==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW5PR11MB5761
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,
        SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no
        version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Mon, 20 Nov 2023 07:35:07 -0800 (PST)


On 11/18/23 08:50, Yury Norov wrote:
> The function searches used_mask for a set bit in a for-loop bit by bit.
> We can do it faster by using atomic find_and_set_bit().
> 
> Signed-off-by: Yury Norov <yury.norov@gmail.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/dma/idxd/perfmon.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/idxd/perfmon.c b/drivers/dma/idxd/perfmon.c
> index fdda6d604262..4dd9c0d979c3 100644
> --- a/drivers/dma/idxd/perfmon.c
> +++ b/drivers/dma/idxd/perfmon.c
> @@ -134,13 +134,9 @@ static void perfmon_assign_hw_event(struct idxd_pmu *idxd_pmu,
>  static int perfmon_assign_event(struct idxd_pmu *idxd_pmu,
>  				struct perf_event *event)
>  {
> -	int i;
> -
> -	for (i = 0; i < IDXD_PMU_EVENT_MAX; i++)
> -		if (!test_and_set_bit(i, idxd_pmu->used_mask))
> -			return i;
> +	int i = find_and_set_bit(idxd_pmu->used_mask, IDXD_PMU_EVENT_MAX);
>  
> -	return -EINVAL;
> +	return i < IDXD_PMU_EVENT_MAX ? i : -EINVAL;
>  }
>  
>  /*