From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756661AbdJKVWO (ORCPT ); Wed, 11 Oct 2017 17:22:14 -0400 Received: from mga01.intel.com ([192.55.52.88]:27461 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752412AbdJKVWK (ORCPT ); Wed, 11 Oct 2017 17:22:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,362,1503385200"; d="scan'208";a="137575553" From: "Luck, Tony" To: Rik van Riel , lkp , Gargi Sharma CC: "kbuild-all@01.org" , "linux-kernel@vger.kernel.org" , "julia.lawall@lip6.fr" , "akpm@linux-foundation.org" , "mingo@kernel.org" , "pasha.tatashin@oracle.com" , "ktkhai@virtuozzo.com" , "oleg@redhat.com" , "ebiederm@xmission.com" , "hch@infradead.org" , linux-ia64 Subject: RE: [PATCH v4 2/2] pid: Remove pidhash Thread-Topic: [PATCH v4 2/2] pid: Remove pidhash Thread-Index: AQHTQptqjRuhkxewzka+NfUR96TlpaLfJrMQ Date: Wed, 11 Oct 2017 21:22:08 +0000 Message-ID: <3908561D78D1C84285E8C5FCA982C28F770037C6@ORSMSX114.amr.corp.intel.com> References: <201710111737.ZHqmaPa5%fengguang.wu@intel.com> <1507731304.21121.185.camel@surriel.com> In-Reply-To: <1507731304.21121.185.camel@surriel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiNTI4ZmQ5MmUtYmVlZC00OTU0LTk5YzItZWEyZTUxZmY4MmRhIiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX0lDIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE3LjIuNS4xOCIsIlRydXN0ZWRMYWJlbEhhc2giOiJFTGdoaXVRUnpwVjcrWkFTSnpUemxIQkhKbHVLOXBcL3B2RG02RUd2bWVzSlIyMmxCRVBuRm5pR0pUTDBFK2R4WSJ9 x-ctpclassification: CTP_IC dlp-product: dlpe-windows dlp-version: 11.0.0.116 dlp-reaction: no-action x-originating-ip: [10.22.254.138] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 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 nfs id v9BLMIwP011651 >        DEFINE(IA64_UPID_SHIFT, 5); > > Grepping for IA64_UPID_SHIFT leads us to some assembly > code implementing fsys_getpid (why is that in assembly?!): The fast system call path has a whole host of serious restrictions on what it can touch. See Documentation/ia64/fsys.txt. Why is getpid() a fast system call? I think there was some application (or perhaps benchmark) that used it a lot. > add r8=IA64_PID_LEVEL_OFFSET,r17 > ;; > ld4 r8=[r8] // r8 = pid->level > add r17=IA64_PID_UPID_OFFSET,r17 // r17 = &pid->numbers[0] > ;; > shl r8=r8,IA64_UPID_SHIFT > ;; > add r17=r17,r8 // r17 = &pid->numbers[pid->level] > ;; > ld4 r8=[r17] // r8 = pid->numbers[pid->level].nr > ;; > mov r17=0 > > Luckily it looks like this is only referencing the first members of struct upid, > and you are removing the last member, so I suspect you will be fine changing the IA64 > to this: > >        BUILD_BUG_ON(sizeof(struct upid) != 16); >        DEFINE(IA64_UPID_SHIFT, 4); > > Tony, does that look ok to you? I think so. Respin and Cc: me on both patches in the series and I'll take it for a spin on h/w to make sure. -Tony From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luck, Tony" Date: Wed, 11 Oct 2017 21:22:08 +0000 Subject: RE: [PATCH v4 2/2] pid: Remove pidhash Message-Id: <3908561D78D1C84285E8C5FCA982C28F770037C6@ORSMSX114.amr.corp.intel.com> List-Id: References: <201710111737.ZHqmaPa5%fengguang.wu@intel.com> <1507731304.21121.185.camel@surriel.com> In-Reply-To: <1507731304.21121.185.camel@surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Rik van Riel , lkp , Gargi Sharma Cc: "kbuild-all@01.org" , "linux-kernel@vger.kernel.org" , "julia.lawall@lip6.fr" , "akpm@linux-foundation.org" , "mingo@kernel.org" , "pasha.tatashin@oracle.com" , "ktkhai@virtuozzo.com" , "oleg@redhat.com" , "ebiederm@xmission.com" , "hch@infradead.org" , linux-ia64 PsKgwqDCoMKgwqDCoMKgwqBERUZJTkUoSUE2NF9VUElEX1NISUZULCA1KTsNCj4NCj4gR3JlcHBp bmcgZm9yIElBNjRfVVBJRF9TSElGVCBsZWFkcyB1cyB0byBzb21lIGFzc2VtYmx5DQo+IGNvZGUg aW1wbGVtZW50aW5nIGZzeXNfZ2V0cGlkICh3aHkgaXMgdGhhdCBpbiBhc3NlbWJseT8hKToNCg0K VGhlIGZhc3Qgc3lzdGVtIGNhbGwgcGF0aCBoYXMgYSB3aG9sZSBob3N0IG9mIHNlcmlvdXMgcmVz dHJpY3Rpb25zIG9uIHdoYXQgaXQgY2FuDQp0b3VjaC4gU2VlIERvY3VtZW50YXRpb24vaWE2NC9m c3lzLnR4dC4gIFdoeSBpcyBnZXRwaWQoKSBhIGZhc3Qgc3lzdGVtIGNhbGw/IEkgdGhpbmsNCnRo ZXJlIHdhcyBzb21lIGFwcGxpY2F0aW9uIChvciBwZXJoYXBzIGJlbmNobWFyaykgdGhhdCB1c2Vk IGl0IGEgbG90Lg0KDQo+ICAgICAgICBhZGQgcjg9SUE2NF9QSURfTEVWRUxfT0ZGU0VULHIxNw0K PiAgICAgICAgOzsNCj4gICAgICAgIGxkNCByOD1bcjhdICAgICAgICAgICAgICAgICAgICAgICAg ICAgICAvLyByOCA9IHBpZC0+bGV2ZWwNCj4gICAgICAgIGFkZCByMTc9SUE2NF9QSURfVVBJRF9P RkZTRVQscjE3ICAgICAgICAvLyByMTcgPSAmcGlkLT5udW1iZXJzWzBdDQo+ICAgICAgICA7Ow0K PiAgICAgICAgc2hsIHI4PXI4LElBNjRfVVBJRF9TSElGVA0KPiAgICAgICAgOzsNCj4gICAgICAg IGFkZCByMTc9cjE3LHI4ICAgICAgICAgICAgICAgICAgICAgICAgICAvLyByMTcgPSAmcGlkLT5u dW1iZXJzW3BpZC0+bGV2ZWxdDQo+ICAgICAgICA7Ow0KPiAgICAgICAgbGQ0IHI4PVtyMTddICAg ICAgICAgICAgICAgICAgICAgICAgICAgIC8vIHI4ID0gcGlkLT5udW1iZXJzW3BpZC0+bGV2ZWxd Lm5yDQo+ICAgICAgICA7Ow0KPiAgICAgICAgbW92IHIxNz0wDQo+DQo+IEx1Y2tpbHkgaXQgbG9v a3MgbGlrZSB0aGlzIGlzIG9ubHkgcmVmZXJlbmNpbmcgdGhlIGZpcnN0IG1lbWJlcnMgb2Ygc3Ry dWN0IHVwaWQsDQo+IGFuZCB5b3UgYXJlIHJlbW92aW5nIHRoZSBsYXN0IG1lbWJlciwgc28gSSBz dXNwZWN0IHlvdSB3aWxsIGJlIGZpbmUgY2hhbmdpbmcgdGhlIElBNjQNCj4gdG8gdGhpczoNCj4N Cj7CoMKgwqDCoMKgwqDCoMKgQlVJTERfQlVHX09OKHNpemVvZihzdHJ1Y3QgdXBpZCkgIT0gMTYp Ow0KPsKgwqDCoMKgwqDCoMKgwqBERUZJTkUoSUE2NF9VUElEX1NISUZULCA0KTsNCj4NCj4gVG9u eSwgZG9lcyB0aGF0IGxvb2sgb2sgdG8geW91Pw0KDQpJIHRoaW5rIHNvLiAgUmVzcGluIGFuZCBD YzogbWUgb24gYm90aCBwYXRjaGVzIGluIHRoZSBzZXJpZXMgYW5kIEknbGwgdGFrZSBpdCBmb3Ig YSBzcGluDQpvbiBoL3cgdG8gbWFrZSBzdXJlLg0KDQotVG9ueQ0K