From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: "Kani, Toshimitsu" To: "dan.j.williams@intel.com" CC: "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "jmoyer@redhat.com" , "tglx@linutronix.de" , "hch@lst.de" , "viro@zeniv.linux.org.uk" , "x86@kernel.org" , "mawilcox@microsoft.com" , "hpa@zytor.com" , "linux-nvdimm@lists.01.org" , "mingo@redhat.com" , "linux-fsdevel@vger.kernel.org" , "ross.zwisler@linux.intel.com" , "jack@suse.cz" Subject: Re: [PATCH v2] x86, uaccess: introduce copy_from_iter_wt for pmem / writethrough operations Date: Fri, 5 May 2017 22:44:40 +0000 Message-ID: <1494024273.30303.71.camel@hpe.com> References: <20170427063054.soejyqocqqrihfdw@gmail.com> <149340820800.28724.16189291963486607562.stgit@dwillia2-desk3.amr.corp.intel.com> <1494016773.30303.69.camel@hpe.com> In-Reply-To: Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: T24gRnJpLCAyMDE3LTA1LTA1IGF0IDE1OjI1IC0wNzAwLCBEYW4gV2lsbGlhbXMgd3JvdGU6DQo+ IE9uIEZyaSwgTWF5IDUsIDIwMTcgYXQgMTozOSBQTSwgS2FuaSwgVG9zaGltaXRzdSA8dG9zaGku a2FuaUBocGUuY29tPg0KPiB3cm90ZToNCiA6DQo+ID4gPiAtLS0NCj4gPiA+IENoYW5nZXMgc2lu Y2UgdGhlIGluaXRpYWwgUkZDOg0KPiA+ID4gKiBzL3dyaXRldGhydS93dC8gc2luY2Ugd2UgYWxy ZWFkeSBoYXZlIGlvcmVtYXBfd3QoKSwNCj4gPiA+IHNldF9tZW1vcnlfd3QoKSwgZXRjLiAoSW5n bykNCj4gPiANCj4gPiBTb3JyeSBJIHNob3VsZCBoYXZlIHNhaWQgZWFybGllciwgYnV0IEkgdGhp bmsgdGhlIHRlcm0gInd0IiBpcw0KPiA+IG1pc2xlYWRpbmcuwqDCoE5vbi10ZW1wb3JhbCBzdG9y ZXMgdXNlZCBpbiBtZW1jcHlfd3QoKSBwcm92aWRlIFdDDQo+ID4gc2VtYW50aWNzLCBub3QgV1Qg c2VtYW50aWNzLg0KPiANCj4gVGhlIG5vbi10ZW1wb3JhbCBzdG9yZXMgZG8sIGJ1dCBtZW1jcHlf d3QoKSBpcyB1c2luZyBhIGNvbWJpbmF0aW9uIG9mDQo+IG5vbi10ZW1wb3JhbCBzdG9yZXMgYW5k IGV4cGxpY2l0IGNhY2hlIGZsdXNoaW5nLg0KPiANCj4gPiBIb3cgYWJvdXQgdXNpbmcgIm5vY2Fj aGUiIGFzIGl0J3MgYmVlbg0KPiA+IHVzZWQgaW4gX19jb3B5X3VzZXJfbm9jYWNoZSgpPw0KPiAN Cj4gVGhlIGRpZmZlcmVuY2UgaW4gbXkgbWluZCBpcyB0aGF0IHRoZSAiX25vY2FjaGUiIHN1ZmZp eCBpbmRpY2F0ZXMNCj4gb3Bwb3J0dW5pc3RpYyAvIG9wdGlvbmFsIGNhY2hlIHBvbGx1dGlvbiBh dm9pZGFuY2Ugd2hlcmVhcyAiX3d0Ig0KPiBzdHJpY3RseSBhcnJhbmdlcyBmb3IgY2FjaGVzIG5v dCB0byBjb250YWluIGRpcnR5IGRhdGEgdXBvbg0KPiBjb21wbGV0aW9uIG9mIHRoZSByb3V0aW5l LiBGb3IgZXhhbXBsZSwgbm9uLXRlbXBvcmFsIHN0b3JlcyBvbiBvbGRlcg0KPiB4ODYgY3B1cyBj b3VsZCBwb3RlbnRpYWxseSBsZWF2ZSBkaXJ0eSBkYXRhIGluIHRoZSBjYWNoZSwgc28NCj4gbWVt Y3B5X3d0IG9uIHRob3NlIGNwdXMgd291bGQgbmVlZCB0byB1c2UgZXhwbGljaXQgY2FjaGUgZmx1 c2hpbmcuDQoNCkkgc2VlLiAgSSBhZ3JlZSB0aGF0IGl0cyBiZWhhdmlvciBpcyBkaWZmZXJlbnQg ZnJvbSB0aGUgZXhpc3Rpbmcgb25lDQp3aXRoICJfbm9jYWNoZSIuICAgVGhhdCBzYWlkLCBJIHRo aW5rICJ3dCIgb3IgIndyaXRlLXRocm91Z2giIGdlbmVyYWxseQ0KbWVhbnMgdGhhdCB3cml0ZXMg YWxsb2NhdGUgY2FjaGVsaW5lcyBhbmQga2VlcCB0aGVtIGNsZWFuIGJ5IHdyaXRpbmcgdG8NCm1l bW9yeS4gIFNvLCBzdWJzZXF1ZW50IHJlYWRzIHRvIHRoZSBkZXN0aW5hdGlvbiB3aWxsIGhpdCB0 aGUNCmNhY2hlbGluZXMuICBUaGlzIGlzIG5vdCB0aGUgY2FzZSB3aXRoIHRoaXMgaW50ZXJmYWNl Lg0KDQpUaGFua3MsDQotVG9zaGkNCiA= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from g2t2353.austin.hpe.com (g2t2353.austin.hpe.com [15.233.44.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 731C021A1348D for ; Fri, 5 May 2017 15:44:44 -0700 (PDT) From: "Kani, Toshimitsu" Subject: Re: [PATCH v2] x86, uaccess: introduce copy_from_iter_wt for pmem / writethrough operations Date: Fri, 5 May 2017 22:44:40 +0000 Message-ID: <1494024273.30303.71.camel@hpe.com> References: <20170427063054.soejyqocqqrihfdw@gmail.com> <149340820800.28724.16189291963486607562.stgit@dwillia2-desk3.amr.corp.intel.com> <1494016773.30303.69.camel@hpe.com> In-Reply-To: Content-Language: en-US Content-ID: <8A23498DC05EBE4FACADA88123ACAA65@NAMPRD84.PROD.OUTLOOK.COM> MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: "dan.j.williams@intel.com" Cc: "jack@suse.cz" , "mawilcox@microsoft.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-nvdimm@lists.01.org" , "mingo@redhat.com" , "viro@zeniv.linux.org.uk" , "hpa@zytor.com" , "linux-fsdevel@vger.kernel.org" , "tglx@linutronix.de" , "hch@lst.de" List-ID: T24gRnJpLCAyMDE3LTA1LTA1IGF0IDE1OjI1IC0wNzAwLCBEYW4gV2lsbGlhbXMgd3JvdGU6DQo+ IE9uIEZyaSwgTWF5IDUsIDIwMTcgYXQgMTozOSBQTSwgS2FuaSwgVG9zaGltaXRzdSA8dG9zaGku a2FuaUBocGUuY29tPg0KPiB3cm90ZToNCiA6DQo+ID4gPiAtLS0NCj4gPiA+IENoYW5nZXMgc2lu Y2UgdGhlIGluaXRpYWwgUkZDOg0KPiA+ID4gKiBzL3dyaXRldGhydS93dC8gc2luY2Ugd2UgYWxy ZWFkeSBoYXZlIGlvcmVtYXBfd3QoKSwNCj4gPiA+IHNldF9tZW1vcnlfd3QoKSwgZXRjLiAoSW5n bykNCj4gPiANCj4gPiBTb3JyeSBJIHNob3VsZCBoYXZlIHNhaWQgZWFybGllciwgYnV0IEkgdGhp bmsgdGhlIHRlcm0gInd0IiBpcw0KPiA+IG1pc2xlYWRpbmcuwqDCoE5vbi10ZW1wb3JhbCBzdG9y ZXMgdXNlZCBpbiBtZW1jcHlfd3QoKSBwcm92aWRlIFdDDQo+ID4gc2VtYW50aWNzLCBub3QgV1Qg c2VtYW50aWNzLg0KPiANCj4gVGhlIG5vbi10ZW1wb3JhbCBzdG9yZXMgZG8sIGJ1dCBtZW1jcHlf d3QoKSBpcyB1c2luZyBhIGNvbWJpbmF0aW9uIG9mDQo+IG5vbi10ZW1wb3JhbCBzdG9yZXMgYW5k IGV4cGxpY2l0IGNhY2hlIGZsdXNoaW5nLg0KPiANCj4gPiBIb3cgYWJvdXQgdXNpbmcgIm5vY2Fj aGUiIGFzIGl0J3MgYmVlbg0KPiA+IHVzZWQgaW4gX19jb3B5X3VzZXJfbm9jYWNoZSgpPw0KPiAN Cj4gVGhlIGRpZmZlcmVuY2UgaW4gbXkgbWluZCBpcyB0aGF0IHRoZSAiX25vY2FjaGUiIHN1ZmZp eCBpbmRpY2F0ZXMNCj4gb3Bwb3J0dW5pc3RpYyAvIG9wdGlvbmFsIGNhY2hlIHBvbGx1dGlvbiBh dm9pZGFuY2Ugd2hlcmVhcyAiX3d0Ig0KPiBzdHJpY3RseSBhcnJhbmdlcyBmb3IgY2FjaGVzIG5v dCB0byBjb250YWluIGRpcnR5IGRhdGEgdXBvbg0KPiBjb21wbGV0aW9uIG9mIHRoZSByb3V0aW5l LiBGb3IgZXhhbXBsZSwgbm9uLXRlbXBvcmFsIHN0b3JlcyBvbiBvbGRlcg0KPiB4ODYgY3B1cyBj b3VsZCBwb3RlbnRpYWxseSBsZWF2ZSBkaXJ0eSBkYXRhIGluIHRoZSBjYWNoZSwgc28NCj4gbWVt Y3B5X3d0IG9uIHRob3NlIGNwdXMgd291bGQgbmVlZCB0byB1c2UgZXhwbGljaXQgY2FjaGUgZmx1 c2hpbmcuDQoNCkkgc2VlLiAgSSBhZ3JlZSB0aGF0IGl0cyBiZWhhdmlvciBpcyBkaWZmZXJlbnQg ZnJvbSB0aGUgZXhpc3Rpbmcgb25lDQp3aXRoICJfbm9jYWNoZSIuICAgVGhhdCBzYWlkLCBJIHRo aW5rICJ3dCIgb3IgIndyaXRlLXRocm91Z2giIGdlbmVyYWxseQ0KbWVhbnMgdGhhdCB3cml0ZXMg YWxsb2NhdGUgY2FjaGVsaW5lcyBhbmQga2VlcCB0aGVtIGNsZWFuIGJ5IHdyaXRpbmcgdG8NCm1l bW9yeS4gIFNvLCBzdWJzZXF1ZW50IHJlYWRzIHRvIHRoZSBkZXN0aW5hdGlvbiB3aWxsIGhpdCB0 aGUNCmNhY2hlbGluZXMuICBUaGlzIGlzIG5vdCB0aGUgY2FzZSB3aXRoIHRoaXMgaW50ZXJmYWNl Lg0KDQpUaGFua3MsDQotVG9zaGkNCiAKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX18KTGludXgtbnZkaW1tIG1haWxpbmcgbGlzdApMaW51eC1udmRpbW1AbGlz dHMuMDEub3JnCmh0dHBzOi8vbGlzdHMuMDEub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtbnZk aW1tCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from g2t2353.austin.hpe.com ([15.233.44.26]:28853 "EHLO g2t2353.austin.hpe.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751721AbdEEWoo (ORCPT ); Fri, 5 May 2017 18:44:44 -0400 From: "Kani, Toshimitsu" To: "dan.j.williams@intel.com" CC: "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "jmoyer@redhat.com" , "tglx@linutronix.de" , "hch@lst.de" , "viro@zeniv.linux.org.uk" , "x86@kernel.org" , "mawilcox@microsoft.com" , "hpa@zytor.com" , "linux-nvdimm@lists.01.org" , "mingo@redhat.com" , "linux-fsdevel@vger.kernel.org" , "ross.zwisler@linux.intel.com" , "jack@suse.cz" Subject: Re: [PATCH v2] x86, uaccess: introduce copy_from_iter_wt for pmem / writethrough operations Date: Fri, 5 May 2017 22:44:40 +0000 Message-ID: <1494024273.30303.71.camel@hpe.com> References: <20170427063054.soejyqocqqrihfdw@gmail.com> <149340820800.28724.16189291963486607562.stgit@dwillia2-desk3.amr.corp.intel.com> <1494016773.30303.69.camel@hpe.com> In-Reply-To: Content-Language: en-US Content-Type: text/plain; charset="utf-8" Content-ID: <8A23498DC05EBE4FACADA88123ACAA65@NAMPRD84.PROD.OUTLOOK.COM> Content-Transfer-Encoding: base64 MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: T24gRnJpLCAyMDE3LTA1LTA1IGF0IDE1OjI1IC0wNzAwLCBEYW4gV2lsbGlhbXMgd3JvdGU6DQo+ IE9uIEZyaSwgTWF5IDUsIDIwMTcgYXQgMTozOSBQTSwgS2FuaSwgVG9zaGltaXRzdSA8dG9zaGku a2FuaUBocGUuY29tPg0KPiB3cm90ZToNCiA6DQo+ID4gPiAtLS0NCj4gPiA+IENoYW5nZXMgc2lu Y2UgdGhlIGluaXRpYWwgUkZDOg0KPiA+ID4gKiBzL3dyaXRldGhydS93dC8gc2luY2Ugd2UgYWxy ZWFkeSBoYXZlIGlvcmVtYXBfd3QoKSwNCj4gPiA+IHNldF9tZW1vcnlfd3QoKSwgZXRjLiAoSW5n bykNCj4gPiANCj4gPiBTb3JyeSBJIHNob3VsZCBoYXZlIHNhaWQgZWFybGllciwgYnV0IEkgdGhp bmsgdGhlIHRlcm0gInd0IiBpcw0KPiA+IG1pc2xlYWRpbmcuwqDCoE5vbi10ZW1wb3JhbCBzdG9y ZXMgdXNlZCBpbiBtZW1jcHlfd3QoKSBwcm92aWRlIFdDDQo+ID4gc2VtYW50aWNzLCBub3QgV1Qg c2VtYW50aWNzLg0KPiANCj4gVGhlIG5vbi10ZW1wb3JhbCBzdG9yZXMgZG8sIGJ1dCBtZW1jcHlf d3QoKSBpcyB1c2luZyBhIGNvbWJpbmF0aW9uIG9mDQo+IG5vbi10ZW1wb3JhbCBzdG9yZXMgYW5k IGV4cGxpY2l0IGNhY2hlIGZsdXNoaW5nLg0KPiANCj4gPiBIb3cgYWJvdXQgdXNpbmcgIm5vY2Fj aGUiIGFzIGl0J3MgYmVlbg0KPiA+IHVzZWQgaW4gX19jb3B5X3VzZXJfbm9jYWNoZSgpPw0KPiAN Cj4gVGhlIGRpZmZlcmVuY2UgaW4gbXkgbWluZCBpcyB0aGF0IHRoZSAiX25vY2FjaGUiIHN1ZmZp eCBpbmRpY2F0ZXMNCj4gb3Bwb3J0dW5pc3RpYyAvIG9wdGlvbmFsIGNhY2hlIHBvbGx1dGlvbiBh dm9pZGFuY2Ugd2hlcmVhcyAiX3d0Ig0KPiBzdHJpY3RseSBhcnJhbmdlcyBmb3IgY2FjaGVzIG5v dCB0byBjb250YWluIGRpcnR5IGRhdGEgdXBvbg0KPiBjb21wbGV0aW9uIG9mIHRoZSByb3V0aW5l LiBGb3IgZXhhbXBsZSwgbm9uLXRlbXBvcmFsIHN0b3JlcyBvbiBvbGRlcg0KPiB4ODYgY3B1cyBj b3VsZCBwb3RlbnRpYWxseSBsZWF2ZSBkaXJ0eSBkYXRhIGluIHRoZSBjYWNoZSwgc28NCj4gbWVt Y3B5X3d0IG9uIHRob3NlIGNwdXMgd291bGQgbmVlZCB0byB1c2UgZXhwbGljaXQgY2FjaGUgZmx1 c2hpbmcuDQoNCkkgc2VlLiAgSSBhZ3JlZSB0aGF0IGl0cyBiZWhhdmlvciBpcyBkaWZmZXJlbnQg ZnJvbSB0aGUgZXhpc3Rpbmcgb25lDQp3aXRoICJfbm9jYWNoZSIuICAgVGhhdCBzYWlkLCBJIHRo aW5rICJ3dCIgb3IgIndyaXRlLXRocm91Z2giIGdlbmVyYWxseQ0KbWVhbnMgdGhhdCB3cml0ZXMg YWxsb2NhdGUgY2FjaGVsaW5lcyBhbmQga2VlcCB0aGVtIGNsZWFuIGJ5IHdyaXRpbmcgdG8NCm1l bW9yeS4gIFNvLCBzdWJzZXF1ZW50IHJlYWRzIHRvIHRoZSBkZXN0aW5hdGlvbiB3aWxsIGhpdCB0 aGUNCmNhY2hlbGluZXMuICBUaGlzIGlzIG5vdCB0aGUgY2FzZSB3aXRoIHRoaXMgaW50ZXJmYWNl Lg0KDQpUaGFua3MsDQotVG9zaGkNCiA= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754050AbdEEWor (ORCPT ); Fri, 5 May 2017 18:44:47 -0400 Received: from g2t2353.austin.hpe.com ([15.233.44.26]:28853 "EHLO g2t2353.austin.hpe.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751721AbdEEWoo (ORCPT ); Fri, 5 May 2017 18:44:44 -0400 X-Greylist: delayed 7499 seconds by postgrey-1.27 at vger.kernel.org; Fri, 05 May 2017 18:44:44 EDT From: "Kani, Toshimitsu" To: "dan.j.williams@intel.com" CC: "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "jmoyer@redhat.com" , "tglx@linutronix.de" , "hch@lst.de" , "viro@zeniv.linux.org.uk" , "x86@kernel.org" , "mawilcox@microsoft.com" , "hpa@zytor.com" , "linux-nvdimm@lists.01.org" , "mingo@redhat.com" , "linux-fsdevel@vger.kernel.org" , "ross.zwisler@linux.intel.com" , "jack@suse.cz" Subject: Re: [PATCH v2] x86, uaccess: introduce copy_from_iter_wt for pmem / writethrough operations Thread-Topic: [PATCH v2] x86, uaccess: introduce copy_from_iter_wt for pmem / writethrough operations Thread-Index: AQHSwFf2pYpBQohMYEm6dbBc4FPj86HmPreAgAAdeoCAAAVzgA== Date: Fri, 5 May 2017 22:44:40 +0000 Message-ID: <1494024273.30303.71.camel@hpe.com> References: <20170427063054.soejyqocqqrihfdw@gmail.com> <149340820800.28724.16189291963486607562.stgit@dwillia2-desk3.amr.corp.intel.com> <1494016773.30303.69.camel@hpe.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: intel.com; dkim=none (message not signed) header.d=none;intel.com; dmarc=none action=none header.from=hpe.com; x-originating-ip: [15.219.163.8] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;AT5PR84MB0260;7:km7ZgC4IAIvZIIruKgcgQMdh7S3GVeJbb4RCojSxuk8I4ywgbAjLNgE7J2IMa1kbX7dNJCojUIa+zGGJhP2Z0JUn4j/IvSJrxTK6UGQGZCWfrz54fqhaGkIbqzr0QjJ8kXRMFh5i3dulvxtgD7qRJdPbIdypsSLDGjSqcphIy9dy8ztxgeotWDhHgUSb6mYBIBbenj09LEALOswDm5KFihmA6q/ridC5kaCjkIq/bw7rC9wWj7R9zUjDuKFUM37skPi8xLPZvhMg2e7CX69oLuOzunAAl7/pPs5MR0PWegL5WiR3p/XkomecIHq9PN/XTOecHZ78HsTi9d6jWo8twg== x-ms-office365-filtering-correlation-id: 488bd2cf-acbd-429f-cbc8-08d4940850df x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(2017030254075)(48565401081)(201703131423075)(201703031133081)(201702281549075);SRVR:AT5PR84MB0260; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(227479698468861); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(6040450)(601004)(2401047)(8121501046)(5005006)(10201501046)(3002001)(93006095)(93001095)(6055026)(6041248)(20161123560025)(20161123562025)(20161123558100)(20161123555025)(20161123564025)(201703131423075)(201703061421075)(201703161042150)(6042181)(6072148);SRVR:AT5PR84MB0260;BCL:0;PCL:0;RULEID:;SRVR:AT5PR84MB0260; x-forefront-prvs: 02981BE340 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(377454003)(377424004)(24454002)(6246003)(6506006)(6436002)(33646002)(5640700003)(7416002)(8666007)(110136004)(4326008)(54906002)(3660700001)(76176999)(50986999)(8936002)(6486002)(53936002)(2906002)(86362001)(38730400002)(2351001)(2501003)(5660300001)(3846002)(6512007)(3280700002)(498600001)(7736002)(305945005)(102836003)(6116002)(54356999)(6916009)(189998001)(2950100002)(5250100002)(66066001)(53546009)(2900100001)(36756003)(229853002)(81166006)(103116003)(93886004)(25786009)(8676002);DIR:OUT;SFP:1102;SCL:1;SRVR:AT5PR84MB0260;H:AT5PR84MB0260.NAMPRD84.PROD.OUTLOOK.COM;FPR:;SPF:None;MLV:sfv;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: <8A23498DC05EBE4FACADA88123ACAA65@NAMPRD84.PROD.OUTLOOK.COM> MIME-Version: 1.0 X-MS-Exchange-CrossTenant-originalarrivaltime: 05 May 2017 22:44:40.2915 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 105b2061-b669-4b31-92ac-24d304d195dc X-MS-Exchange-Transport-CrossTenantHeadersStamped: AT5PR84MB0260 X-OriginatorOrg: hpe.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id v45MiuYs013329 On Fri, 2017-05-05 at 15:25 -0700, Dan Williams wrote: > On Fri, May 5, 2017 at 1:39 PM, Kani, Toshimitsu > wrote: : > > > --- > > > Changes since the initial RFC: > > > * s/writethru/wt/ since we already have ioremap_wt(), > > > set_memory_wt(), etc. (Ingo) > > > > Sorry I should have said earlier, but I think the term "wt" is > > misleading.  Non-temporal stores used in memcpy_wt() provide WC > > semantics, not WT semantics. > > The non-temporal stores do, but memcpy_wt() is using a combination of > non-temporal stores and explicit cache flushing. > > > How about using "nocache" as it's been > > used in __copy_user_nocache()? > > The difference in my mind is that the "_nocache" suffix indicates > opportunistic / optional cache pollution avoidance whereas "_wt" > strictly arranges for caches not to contain dirty data upon > completion of the routine. For example, non-temporal stores on older > x86 cpus could potentially leave dirty data in the cache, so > memcpy_wt on those cpus would need to use explicit cache flushing. I see. I agree that its behavior is different from the existing one with "_nocache". That said, I think "wt" or "write-through" generally means that writes allocate cachelines and keep them clean by writing to memory. So, subsequent reads to the destination will hit the cachelines. This is not the case with this interface. Thanks, -Toshi