Messages in this thread | | | From | "kanchan" <> | 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 |
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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 <joshi.k@samsung.com> 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
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