From: Daeho Jeong Subject: Question about CFQ queue preemption with REQ_PRIO Date: Tue, 29 Mar 2016 03:08:42 +0000 (GMT) Message-ID: <742004835.98611459220921290.JavaMail.weblogic@epmlwas04d> Reply-To: daeho.jeong@samsung.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: base64 Cc: linux-block@vger.kernel.org, linux-ext4@vger.kernel.org To: axboe@fb.com Return-path: Received: from mailout1.samsung.com ([203.254.224.24]:36608 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751230AbcC2DIp (ORCPT ); Mon, 28 Mar 2016 23:08:45 -0400 Received: from epcpsbgr4.samsung.com (u144.gpu120.samsung.co.kr [203.254.230.144]) by mailout1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0O4S02X1062IZ810@mailout1.samsung.com> for linux-ext4@vger.kernel.org; Tue, 29 Mar 2016 12:08:42 +0900 (KST) MIME-version: 1.0 Sender: linux-ext4-owner@vger.kernel.org List-ID: SGksDQoNCkZpcnN0IG9mIGFsbCwgSSBhbSBhIGJpZyBmYW4gb2YgdGhlIENGUSBJL08gc2NoZWR1 bGVyLiBUaGFuayB5b3UgZm9yIHlvdXIgY29udHJpYnV0aW9uLiA6LSkNCkkgaGF2ZSBhIHF1ZXN0 aW9uIGFib3V0IHRoZSBiZWxvdyBDRlEgcXVldWUgcHJlZW1wdGlvbiBjb25kaXRpb24gaW4gY2Zx X3Nob3VsZF9wcmVlbXB0KCkuDQoNCiAgICAgICAgLyoNCiAgICAgICAgICogU28gYm90aCBxdWV1 ZXMgYXJlIHN5bmMuIExldCB0aGUgbmV3IHJlcXVlc3QgZ2V0IGRpc2sgdGltZSBpZg0KICAgICAg ICAgKiBpdCdzIGEgbWV0YWRhdGEgcmVxdWVzdCBhbmQgdGhlIGN1cnJlbnQgcXVldWUgaXMgZG9p bmcgcmVndWxhciBJTy4NCiAgICAgICAgICovDQogICAgICAgIGlmICgocnEtPmNtZF9mbGFncyAm IFJFUV9QUklPKSAmJiAhY2ZxcS0+cHJpb19wZW5kaW5nKQ0KICAgICAgICAgICAgICAgIHJldHVy biB0cnVlOw0KDQpOb3JtYWxseSwgUkVRX1BSSU8gZmxhZyBpcyB1c2VkIGZvciBSRUFEIHJlcXVl c3RzIGZvciByZWFkaW5nIG1ldGFkYXRhLCBzbyB0aGVuLCB0aGUgQ0ZRDQpxdWV1ZSBjb250YWlu aW5nICJycSIgbXVzdCBiZSBhIFNZTkMgcXVldWUgYW5kIGNmcXEgaXMgYWxzbyBhIFNZTkMgcXVl dWUgYmVjYXVzZSB3ZQ0KYWxyZWFkeSBwYXNzZWQgdGhyb3VnaCB0aGUgYmVsb3cgY29uZGl0aW9u LiBUaGVyZWZvcmUsIHRoZSBjb21tZW50ICJTbyBib3RoIHF1ZXVlcyBhcmUgc3luYyINCmlzIFRS VUUuDQoNCiAgICAgICAgaWYgKHJxX2lzX3N5bmMocnEpICYmICFjZnFfY2ZxcV9zeW5jKGNmcXEp KQ0KICAgICAgICAgICAgICAgIHJldHVybiB0cnVlOw0KDQpCdXQsIEkgYW0gd29yZGVyaW5nIGFi b3V0IHRoZSBjYXNlIG9mIHRoYXQgYW4gYXN5bmNocm9ub3VzIFdSSVRFIHJlcXVlc3Qgd2l0aCBS RVFfUFJJTw0KaXMgaW5zZXJ0ZWQgaW50byB0aGUgcmVxdWVzdCBxdWV1ZS4gQWN0dWFsbHksIGV4 dDQgbWV0YWRhdGEgYXJlIHN1Ym1pdHRlZCBhcyBhc3luY2hyb25vdXMNCldSSVRFIHJlcXVlc3Rz IHdpdGggUkVRX1BSSU8gYnkga3dvcmtlci4gSW4gdGhpcyBjYXNlLCBhc3luY2hyb25vdXMgV1JJ VEUgcmVxdWVzdHMgY2FuDQpwcmVlbXB0IHN5bmNocm9ub3VzIFJFQUQgcmVxdWVzdHMuIEFueXdh eXMsIEkgdGhpbmsgZXh0NCBtZXRhZGF0YSB3cml0ZSBzaG91bGQgaGF2ZQ0KcHJpb3JpdHkgZm9y IGJldHRlciBmaWxlc3lzdGVtIGNhbGwgcmVzcG9uc2l2ZW5lc3MsIGJ1dCB0aGUgY29tbWVudCBp biB0aGUgc291cmNlIGNvZGUsDQoiU28gYm90aCBxdWV1ZXMgYXJlIHN5bmMiLCBtYWtlcyBtZSBh IGxpdHRsZSBjb25mdXNlZC4NCg0KQ291bGQgeW91IGV4cGxhaW4gYWJvdXQgdGhlIG1lYW5pbmcg b2YgdGhlIGNvbW1lbnQgaW4gdGhlIHNvdXJjZSBjb2RlPw0KDQpCZXN0IFJlZ2FyZHMsDQoNCg==