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[209.132.180.67]) by mx.google.com with ESMTP id j25si308063otk.154.2020.04.06.14.40.29; Mon, 06 Apr 2020 14:40:41 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=kvQOK4Gg; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726331AbgDFVkC (ORCPT + 99 others); Mon, 6 Apr 2020 17:40:02 -0400 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:10876 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725933AbgDFVkC (ORCPT ); Mon, 6 Apr 2020 17:40:02 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 06 Apr 2020 14:38:19 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 06 Apr 2020 14:40:01 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 06 Apr 2020 14:40:01 -0700 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 6 Apr 2020 21:40:00 +0000 Received: from [10.2.164.193] (172.20.13.39) by DRHQMAIL107.nvidia.com (10.27.9.16) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 6 Apr 2020 21:39:59 +0000 Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver From: Sowjanya Komatineni To: Dmitry Osipenko , , , , , , CC: , , , , , References: <1585963507-12610-1-git-send-email-skomatineni@nvidia.com> <1585963507-12610-7-git-send-email-skomatineni@nvidia.com> <200bb96e-2d07-764f-9e14-55538dc742fd@gmail.com> <23bfab09-b464-6e51-9843-06d13000e9b9@nvidia.com> <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.com> <12a834ac-52b1-6dc0-7d3a-3e6a1fa85a2a@gmail.com> Message-ID: Date: Mon, 6 Apr 2020 14:39:58 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To DRHQMAIL107.nvidia.com (10.27.9.16) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1586209099; bh=o0hT2mgBLzZYzTwAxCmEeFHH5UCRVvtcMzb/Xs+59co=; h=X-PGP-Universal:Subject:From:To:CC:References:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=kvQOK4GgGgPHSuaGCrkAEoD0fzmKhvZbHlQmJWp1gFjW7cdoyx4QWJYTb4DgimWxO bpvvSQXr42gHwohZSAMAN98Z19FbSRdV1mWpJ63aNUSsu5sehMjGKB5YUPh6QVSEqn 4iYE4xJjzSzwAderHqXG7FFt92y9zgQXBNBtetmBlGt/C8GJa8Zq/bYljyHnR814OR esili6YrDmQzrfqPprS+4sGbSRDzl3Pd+EGQtesSkGMwam9tAVV5vD7Rd/LpAa7bXv sfAZl4DQ8g80XQV36cYYjII3rw38ikQl+klym4HGy8cSfWLWq5Rb4/esUlNty08jF9 ehJU23kkDxTFA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/6/20 2:15 PM, Sowjanya Komatineni wrote: > > On 4/6/20 2:11 PM, Dmitry Osipenko wrote: >> External email: Use caution opening links or attachments >> >> >> 07.04.2020 00:02, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>>>>>> Am I understanding correctly that this thread will take 100% CPU, >>>>>>>> spinning here, if more than 2 frame-captures queued? >>>>>>> on more than 2 frames captures, it breaks thread and on next=20 >>>>>>> wakeup it >>>>>>> continues >>>>>> The wait_event() won't wait if condition is true. >>>>> condition is checked when waitqueue is woken up >>>> https://elixir.bootlin.com/linux/v5.6.2/source/include/linux/wait.h#L4= 62=20 >>>> >>> process is put to sleep until the condition evaluates to true or signal >>> is received. >>> >>> condition is checked each time the waitqueue head is woken up. >> This is a wrong assumption in accordance to the code. > > when every buffer is available as long as we are in streaming, we=20 > should process it. > > So if wake up happens when list has buffer, it will be processed but=20 > at a time we limit processing 2 simultaneous buffer capture starts only. > Fixing typo. I meant when ever buffer is available as long as we are in streaming, we=20 should process it. So capture thread processes as long as buffers are available from user=20 space limiting 2 simultaneous trigger of captures and thread will be in=20 sleep when capture buffers list is empty or no stop thread is signaled.