From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by dpdk.org (Postfix) with ESMTP id 8807C1B19D for ; Thu, 11 Oct 2018 12:14:31 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Oct 2018 03:14:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,368,1534834800"; d="scan'208";a="270416704" Received: from aburakov-mobl1.ger.corp.intel.com (HELO [10.237.220.79]) ([10.237.220.79]) by fmsmga005.fm.intel.com with ESMTP; 11 Oct 2018 03:13:17 -0700 To: Shreyansh Jain Cc: ferruh.yigit@intel.com, dev@dpdk.org References: <20180925125423.7505-1-shreyansh.jain@nxp.com> <20180925125423.7505-4-shreyansh.jain@nxp.com> <894130a9-017c-348d-31f8-c4c23f517f25@nxp.com> <2d2e9008-fb5b-3ecd-2d2c-e86250f5d363@nxp.com> <5e153c76-6eaa-e6a5-28ed-7cec191d4581@intel.com> <2c377b57-c418-5c03-a23d-5da91ef898d0@nxp.com> <16940ff0-278c-2376-1a86-6beaf0770a09@nxp.com> From: "Burakov, Anatoly" Message-ID: <4f10749d-b6e8-e257-0606-2fbb3c1e3d76@intel.com> Date: Thu, 11 Oct 2018 11:13:17 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <16940ff0-278c-2376-1a86-6beaf0770a09@nxp.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH 3/5] common/dpaax: add library for PA VA translation table X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Oct 2018 10:14:32 -0000 On 11-Oct-18 11:07 AM, Shreyansh Jain wrote: > On Thursday 11 October 2018 03:32 PM, Shreyansh Jain wrote: >> On Thursday 11 October 2018 02:33 PM, Burakov, Anatoly wrote: >>> On 09-Oct-18 11:45 AM, Shreyansh Jain wrote: >>>> On Tuesday 25 September 2018 07:09 PM, Shreyansh Jain wrote: >>>>> Hello Anatoly, >>>>> >>>>> On Tuesday 25 September 2018 06:58 PM, Burakov, Anatoly wrote: >>>>>> On 25-Sep-18 1:54 PM, Shreyansh Jain wrote: >>>>>>> A common library, valid for dpaaX drivers, which is used to maintain >>>>>>> a local copy of PA->VA translations. >>>>>>> >>>>>>> In case of physical addressing mode (one of the option for FSLMC, >>>>>>> and >>>>>>> only option for DPAA bus), the addresses of descriptors Rx'd are >>>>>>> physical. These need to be converted into equivalent VA for rte_mbuf >>>>>>> and other similar calls. >>>>>>> >>>>>>> Using the rte_mem_virt2iova or rte_mem_virt2phy is expensive. This >>>>>>> library is an attempt to reduce the overall cost associated with >>>>>>> this translation. >>>>>>> >>>>>>> A small table is maintained, containing continuous entries >>>>>>> representing a continguous physical range. Each of these entries >>>>>>> stores the equivalent VA, which is fed during mempool creation, or >>>>>>> memory allocation/deallocation callbacks. >>>>>>> >>>> >>>> [...] >>>> >>>>> >>>>>> >>>>>> Also, a couple of nitpicks below. >>>>>> >>>>>>>   cosnfig/common_base                            |   5 + >>>>>>>   config/common_linuxapp                        |   5 + >>>>>>>   drivers/common/Makefile                       |   4 + >>>>>>>   drivers/common/dpaax/Makefile                 |  31 ++ >>>>>>>   drivers/common/dpaax/dpaax_iova_table.c       | 509 >>>>>>> ++++++++++++++++++ >>>>>>>   drivers/common/dpaax/dpaax_iova_table.h       | 104 ++++ >>>>>>>   drivers/common/dpaax/dpaax_logs.h             |  39 ++ >>>>>>>   drivers/common/dpaax/meson.build              |  12 + >>>>>> >>>>>> >>>>>> >>>>>>> +    DPAAX_DEBUG("Add: Found slot at (%"PRIu64")[(%zu)] for >>>>>>> vaddr:(%p)," >>>>>>> +            " phy(%"PRIu64"), len(%zu)", entry[i].start, e_offset, >>>>>>> +            vaddr, paddr, length); >>>>>>> +    return 0; >>>>>>> +} >>>>>>> + >>>>>>> +int >>>>>>> +dpaax_iova_table_del(phys_addr_t paddr, size_t len __rte_unused) >>>>>> >>>>>> len is not unused. >>>>> >>>>> I will fix this. >>>>> Actually, this function itself is useless - more for symmetry reason. >>>>> Callers would be either simply updating the table, or ignoring it >>>>> completely. But, yes, this is indeed wrong that I set that unused. >>>>> >>>> >>>> Actually, I was wrong in my first reply. In case of >>>> dpaax_iova_table_del(), len is indeed redundant. This is because the >>>> mapping is for a complete page (min of 2MB size), even if the >>>> request is for lesser length. So, removal of a single entry (of >>>> fixed size) would be done. >>>> >>>> In fact, while on this, I think deleting a PA->VA entry itself is >>>> incorrect (not just useless). A single entry (~2MB equivalent) can >>>> represent multiple users (working on a rte_malloc'd area, for >>>> example). So, effectively, its always an update - not an add or del. >>> >>> I'm not sure what you mean here. If you got a mem event about memory >>> area being freed, it's guaranteed to *not* have any users - neither >>> malloc, nor any other memory. And len is always page-aligned. >> >> ok. Maybe I am getting this wrong, but consider this: >> >> 1) hugepage size=2MB >> 2) a = malloc(1M) >>    this will pin an entry in table for a block starting at VA=(a) and >> PA=(a'). Each entry is of 2MB length - that means, even if someone >> were to access a+1048577 for an equivalent PA, they would get it >> (though, that is a incorrect access). >> 3) b = malloc(1M) >>    this *might* lead to a case where same 2MB page is used and >> VA=(b==(a+1MB)). Being hugepage backed, PA=(b=PA(a)+1M). >> = After b, the PA-VA table has a single entry of 2MB, representing two >> mallocs. It can be used for translation for any thread requesting PAs >> of a or b. >> 4) Free(a) >>   - this would attempt to remove one 2MB entry from PA-VA table. But, >> 'b' is already valid. Access to get_pa(VA(b)) should return me the PA(b). >>   - 'len' is not even used as the entry in PA-VA table is of a fixed >> size. > > Just to add to this: > - if talking about the mem_event callback, it definitely won't be a case > where same page is still being served under another rte_malloc > - But, calls can come to delete from users of PA-VA table based on their > own rte_free(). > > And, your comment makes me think - I should probably del entry from the > table only when mem_event callback is received. Mem events are not triggered on rte_free(), they're triggered on page deallocation. A call to rte_free/rte_memzone_free/rte_mempool_free etc. *might* trigger a page deallocation, but *only* if the memory area being freed encompasses an entire page. If you rte_malloc() 64 bytes and then rte_free() those 64 bytes, you won't get a mem event *unless* these were the only 64 bytes allocated on a particular page, and the entire page is no longer used by anything else. > >> >> In the above, (3) is an assumption I am making based on my >> understanding how mem allocator is working. Is that wrong? >> >> Basically, this is a restriction of this table - it has a min chunk of >> 2MB - even for 1G hugepages - and hence, it is not possible to honor >> deletes. I know this is convoluted logic - but, this keeps it simple >> and use-able without much performance impact. >> >> [...] >> > > -- Thanks, Anatoly