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Petersen'" Cc: , , , , , , , , In-Reply-To: Subject: RE: [PATCH v3 7/7] fs/ext4,jbd2: add support for passing write-hint with journal Date: Wed, 3 Apr 2019 19:12:00 +0530 Message-ID: <11cd01d4ea23$1bb6b260$53241720$@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 15.0 Thread-Index: AQE0pJf9fllz3AfCWkxgRsQT/9U6SAH+2IJzAfiHPhcCU6VO6ac4nyvg Content-Language: en-us X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrPKsWRmVeSWpSXmKPExsWy7bCmhm7QjiUxBtdeKVn8nj6F1eL/nmNs FuffHmay2HtL22LmvDtsFnv2nmSxuLxrDpvF/GVP2S2WH//HZHFlyiJmBy6Pic3v2D12zrrL 7rF5Sb3Hx6e3WDz6tqxi9Pi8SS6ALYrLJiU1J7MstUjfLoEr49alfYwFV/gqpq5/xNrA2MnT xcjBISFgItH3u6yLkYtDSGA3o8SNt4eZIZxPjBJ/Hy6Gcr4xSsy+sh7I4QTr2LCzhQkisReo 5XEzG0hCSOA5o0TXCiMQm01AVeLej16wuIiAucTECUdZQBqYBf4xShye+ZIdJMEpoCnx5HQP I4gtLBAt8fjDXLAGFgEViSNNzUwgNq+ApcTjW5ugbEGJkzOfsIDYzALyEtvfzoG6SEFi96ej rBDL3CQWNZ1ihqgRl3h59Ag7yGIJgW52ie/b37FDNLhI/Pl/gw3CFpZ4dXwLVFxK4mV/G5Rd LPHrzlFmiOYORonrDTNZIBL2Ehf3/GUChR4z0Afrd+lDLOOT6P39hAkSqLwSHW1CENWKEvcm PWWFsMUlHs5YAmV7SLyY9oZtAqPiLCSvzULy2iwkL8xCWLaAkWUVo2RqQXFuemqxaYFhXmq5 XnFibnFpXrpecn7uJkZwstLy3ME465zPIUYBDkYlHt4fq5fECLEmlhVX5h5ilOBgVhLhPdO/ IEaINyWxsiq1KD++qDQntfgQozQHi5I471zZudFCAumJJanZqakFqUUwWSYOTqkGRiPWxvny Jm+/XcozMBRhNr21vku4eMb8p8d8nNJmu23s2fZ8yoKSqY94SlZdn782Wf8kr+f/VVYPzyzf VRm3Xzb+SoFS9o3G0P9scRn1+2/XSVYY8/RO1PM5p6hutzVNYY1sZZdJ9JSXRtfuzPQTdHGM 3vtouVTxpVzdi2lTtrfW/L2ao2hxS4mlOCPRUIu5qDgRAObnvEBSAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrAIsWRmVeSWpSXmKPExsWy7bCSnG7gjiUxBpcPcVr8nj6F1eL/nmNs FuffHmay2HtL22LmvDtsFnv2nmSxuLxrDpvF/GVP2S2WH//HZHFlyiJmBy6Pic3v2D12zrrL 7rF5Sb3Hx6e3WDz6tqxi9Pi8SS6ALYrLJiU1J7MstUjfLoEr49alfYwFV/gqpq5/xNrA2MnT xcjJISFgIrFhZwtTFyMXh5DAbkaJp9/PMEIkxCWar/1gh7CFJVb+ew5mCwk8ZZTYtCgExGYT UJW496OXDcQWETCXmDjhKAvIIGaBDiaJVUchBgkJvGCU+PmlCMTmFNCUeHK6BywuLBApcePW F2YQm0VAReJIUzMTiM0rYCnx+NYmKFtQ4uTMJ0BDOYCG6km0bQRrZRaQl9j+dg4zxG0KErs/ HWWFuMFNYlHTKWaIGnGJl0ePsE9gFJ6FZNIshEmzkEyahaRjASPLKkbJ1ILi3PTcYsMCo7zU cr3ixNzi0rx0veT83E2M4HjT0trBeOJE/CFGAQ5GJR7eBSuXxAixJpYVV+YeYpTgYFYS4T3T vyBGiDclsbIqtSg/vqg0J7X4EKM0B4uSOK98/rFIIYH0xJLU7NTUgtQimCwTB6dUAyNr/+q6 FAaGTe9OPnKNMbiV8K9DRf+oz8eKHvPazscinI2df0Tm7jR9cDvDc6/wtcO++TLJvx459itv kJA0yq04kfot38QgwF3N+KsK2+2517+f+XL/wdfOK9wyu65dvNjyPOJn7JSd/HuC4y/9f+Q7 f1/bl2gjsbPTKwwWp4vKlQguOvW010iJpTgj0VCLuag4EQCEmH9rswIAAA== X-CMS-MailID: 20190403134241epcas5p4743b5b4e1584213856f1f963fa236b68 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P X-CMS-RootMailID: 20190329075800epcas2p4731f10eabf7d70dc7096117d161b05a3 References: <1553846032-4451-1-git-send-email-joshi.k@samsung.com> <1553846032-4451-8-git-send-email-joshi.k@samsung.com> Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Hi Martin, > Why not just introduce REQ_JOURNAL and let the device driver decide how to turn that into something appropriate for the device? It began with that kind of thought/goal i.e. introduce something just for FS journal. But it seems to have evolved for good. Current approach extends write-hint infra so that whole thing becomes extensible for other kind of use-cases (than FS journal) as well. Also in this approach, driver will do little, while block-layer will do majority of the work. > That's what I'll need for SCSI. Existing SCSI streams are not a good fit. Do you see that it's difficult for SCSI to use write-hint infrastructure for streams? -----Original Message----- From: Martin K. Petersen [mailto:martin.petersen@oracle.com] Sent: Wednesday, April 03, 2019 8:28 AM To: Kanchan Joshi Cc: linux-kernel@vger.kernel.org; linux-block@vger.kernel.org; linux-nvme@lists.infradead.org; linux-fsdevel@vger.kernel.org; linux-ext4@vger.kernel.org; axboe@fb.com; prakash.v@samsung.com; anshul@samsung.com; joshiiitr@gmail.com Subject: Re: [PATCH v3 7/7] fs/ext4,jbd2: add support for passing write-hint with journal Kanchan, > For NAND based SSDs, mixing of data with different life-time reduces > efficiency of internal garbage-collection. During FS operations, > series of journal updates will follow/precede series of data/meta > updates, causing intermixing inside SSD. By passing a write-hint with > journal, its write can be isolated from other data/meta writes, > leading to endurance/performance benefit on SSD. Why not just introduce REQ_JOURNAL and let the device driver decide how to turn that into something appropriate for the device? That's what I'll need for SCSI. Existing SCSI streams are not a good fit. -- Martin K. Petersen Oracle Linux Engineering