From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753042AbaJFQ0T (ORCPT ); Mon, 6 Oct 2014 12:26:19 -0400 Received: from mailout4.samsung.com ([203.254.224.34]:18556 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752163AbaJFQ0R (ORCPT ); Mon, 6 Oct 2014 12:26:17 -0400 X-AuditID: cbfee690-f79ab6d0000046f7-68-5432c2a7829a Date: Mon, 06 Oct 2014 16:26:15 +0000 (GMT) From: PINTU KUMAR Subject: Re: Re: [PATCH 1/1] [ion]: system-heap use PAGE_ALLOC_COSTLY_ORDER for high order To: Laura Abbott , Heesub Shin , "akpm@linux-foundation.org" , "gregkh@linuxfoundation.org" , "john.stultz@linaro.org" , "rebecca@android.com" , "ccross@android.com" , "devel@driverdev.osuosl.org" , "linux-kernel@vger.kernel.org" Cc: IQBAL SHAREEF , "pintu_agarwal@yahoo.com" , Vishnu Pratap Singh , "cpgs@samsung.com" Reply-to: pintu.k@samsung.com MIME-version: 1.0 X-MTR: 20141006153958031@pintu.k Msgkey: 20141006153958031@pintu.k X-EPLocale: en_US.windows-1252 X-Priority: 3 X-EPWebmail-Msg-Type: personal X-EPWebmail-Reply-Demand: 0 X-EPApproval-Locale: X-EPHeader: ML X-MLAttribute: X-RootMTR: 20141006153958031@pintu.k X-ParentMTR: X-ArchiveUser: X-CPGSPASS: Y X-ConfirmMail: N,general Content-type: text/plain; charset=windows-1252 MIME-version: 1.0 Message-id: <1689163249.303621412612771982.JavaMail.weblogic@epmlwas07b> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrMIsWRmVeSWpSXmKPExsWyRsSkSnf5IaMQg5mfDC0u75rD5sDo8XmT XABjFJdNSmpOZllqkb5dAlfGzo0nGAt+yVWsO72KvYFxglwXIweHkICSxOtFtl2MnBwSAiYS W86sZ4awxSQu3FvPBmILCSxllDj5UQ2m5vXL70xdjFxA8TmMEsdubwJrYBFQkVi8cj8LiM0m oCGx8skFsLiwQJTEh93/2UAaRATuMEs8+HYKzGEW2MMo8aP7DRvEFbISlzu5QBp4BQQlTs58 wgISlhBQkPiyzxEirCix+Pc3dogj5CSWTL3MBGHzSsxof8oCE5/2dQ3UA9IS52dtYIR5ZvH3 x1BxfqCbd0D1CkhMPXMQqkZVYk3Xaag5fBJrFr5lganfdWo5M8yuho2/oW6QkNja8oQVxGYG um1K90N2CNtA4siiOazoXuEV8JD4v1MC5HMJgYkcEgdf3GGcwKg0C0nZLCSjZiEZhaxmASPL KkbR1ILkguKk9CITveLE3OLSvHS95PzcTYzAtHD637MJOxjvHbA+xCjAwajEwxu5wzBEiDWx rLgy9xCjKTCaJjJLiSbnA5NPXkm8obGZkYWpiamxkbmlmZI472upn8FCAumJJanZqakFqUXx RaU5qcWHGJk4OKUaGN1X20SxaiqWW+5W0/9l4n747pk7XJoSmg91+Y9ek5phmyJp4bx0Q+ST qHt9y86qz5y/aWbR00p/Vj3rrBVHvj87NHeSq5R7w2aLkopLHotPX3fMX/05fqHTlqRbphZa XaFv+pqXh8ncDND6x3r40ylte30F4aqbCrobP+lXr1/j9rtu3mT7iUosxRmJhlrMRcWJAAvx JpQGAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrKKsWRmVeSWpSXmKPExsVy+t/tXt3lh4xCDL4e17S4vGsOmwOjx+dN cgGMUWk2GamJKalFCql5yfkpmXnptkrewfHO8aZmBoa6hpYW5koKeYm5qbZKLj4Bum6ZOUBD lRTKEnNKgUIBicXFSvp2NkX5pSWpChn5xSW2StGG5kZ6RgZ6pkZ6hqaxVoYGBkamQDUJaRk7 N55gLPglV7Hu9Cr2BsYJcl2MHBxCAkoSrxfZdjFyckgImEi8fvmdCcIWk7hwbz1bFyMXUMkc RoljtzcxgyRYBFQkFq/czwJiswloSKx8cgEsLiwQJfFh93+wBhGBO8wSD76dAnOYBfYwSvzo fsMGsU1W4nInF0gDr4CgxMmZT1hAwhICChJf9jlChBUlFv/+xg5xhJzEkqmXoQ7ilZjR/pQF Jj7t6xpmCFta4vysDYwwRy/+/hgqzg908w6oXgGJqWcOQtWoSqzpOg01h09izcK3LDD1u04t Z4bZ1bDxN9QNEhJbW56wgtjMQLdN6X7IDmEbSBxZNIcV3Su8Ah4S/3dKTGCUnYUkMwtJ9ywk 3chqFjCyrGIUTS1ILihOSq8w1CtOzC0uzUvXS87P3cQITkLPFu5g/HLe+hCjAAejEg9vxA7D ECHWxLLiytxDjBIczEoivObzjEKEeFMSK6tSi/Lji0pzUosPMZoCI20is5Rocj4wQeaVxBsa m5ibGptaGBiam5spifPevZkUJCSQnliSmp2aWpBaBNPHxMEp1cAoortA3kl5w2+zc6lS5/q6 bsspbGWU27BK57RZh1co6w2zjtp/5/wfJappBz3veMkhkHpMaKo03wwBQZkrpsv+qa1b0D7T arlZnlKa1YPt4T0fNgQeuvdmT+Wz0D2rRaXsq+8+dvuh9JuhPGQ9s/Jtz9Y/AtMOfe2csv3A m70qO6t+7v4xm0dUiaU4I9FQi7moOBEAMbQNvFgDAAA= DLP-Filter: Pass X-CFilter-Loop: Reflected 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 s96GQObZ007703 Hi, >________________________________ > From: Laura Abbott >To: Heesub Shin ; Pintu Kumar ; akpm@linux-foundation.org; gregkh@linuxfoundation.org; john.stultz@linaro.org; rebecca@android.com; ccross@android.com; devel@driverdev.osuosl.org; linux-kernel@vger.kernel.org >Cc: iqbal.ams@samsung.com; pintu_agarwal@yahoo.com; vishnu.ps@samsung.com >Sent: Monday, 6 October 2014 7:37 PM >Subject: Re: [PATCH 1/1] [ion]: system-heap use PAGE_ALLOC_COSTLY_ORDER for high order > > >On 10/6/2014 3:27 AM, Heesub Shin wrote: > > > > >> Hello Kumar, >> >> On 10/06/2014 05:31 PM, Pintu Kumar wrote: >>> The Android ion_system_heap uses allocation fallback mechanism >>> based on 8,4,0 order pages available in the system. >>> It changes gfp flags based on higher order allocation request. >>> This higher order value is hard-coded as 4, instead of using >>> the system defined higher order value. >>> Thus replacing this hard-coded value with PAGE_ALLOC_COSTLY_ORDER >>> which is defined as 3. >>> This will help mapping the higher order request in system heap with >>> the actual allocation request. >> >> Quite reasonable. >> >> Reviewed-by: Heesub Shin >> >> BTW, Anyone knows how the allocation order (8,4 and 0) was decided? I >> think only Google guys might know the answer. >> >> regards, >> heesub >> > >My understanding was this was completely unrelated to the costly order >and was related to the page sizes corresponding to IOMMU page sizes >(1MB, 64K, 4K). This won't make a difference for the uncached page >pool case but for the not page pool case, I'm not sure if there would >be a benefit for trying to get 32K pages with some effort vs. just >going back to 4K pages. No, it is not just related to IOMMU case. It comes into picture also for normal system-heap allocation (without iommu cases). Also, it is applicable for both uncached and page_pool cases. Please also check the changes under ion_system_heap_create. Here the gfp_flags are set under the pool structure. This value is used in ion_page_pool_alloc_pages. In both the cases, it internally calls alloc_pages, with this gfp_flags. Now, during memory pressure scenario, when alloc_pages moves to slowpath this gfp_flags will be used to decide allocation retry. In the current code, the higher-order flag is set only when order is greater than 4. But, in MM, the order 4 is also considered as higher-order request. This higher-order is decided based on PAGE_ALLOC_COSTLY_ORDER (3) value. Hence, I think this value should be in sync with the MM code. > >Do you have any data/metrics that show a benefit from this patch? I think it is not related to any data or metrics. It is about replacing the hard-coded higher-order check to be in sync with the MM code. {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I