From: Christoph Hellwig <hch@lst.de> To: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>, Sebastian Ott <sebott@linux.ibm.com>, Sagi Grimberg <sagi@grimberg.me>, Max Gurtovoy <maxg@mellanox.com>, Bart Van Assche <bvanassche@acm.org>, Ulf Hansson <ulf.hansson@linaro.org>, Alan Stern <stern@rowland.harvard.edu>, Oliver Neukum <oneukum@suse.com>, linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, linux-mmc@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, "PDL,MEGARAIDLINUX" <megaraidlinux.pdl@broadcom.com>, PDL-MPT-FUSIONLINUX <mpt-fusionlinux.pdl@broadcom.com>, linux-hyperv@vger.kernel.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH 10/13] megaraid_sas: set virt_boundary_mask in the scsi host Date: Mon, 17 Jun 2019 10:44:33 +0200 [thread overview] Message-ID: <20190617084433.GA7969@lst.de> (raw) In-Reply-To: <98f6557ae91a7cdfe8069fcf7d788c88@mail.gmail.com> On Fri, Jun 14, 2019 at 01:28:47AM +0530, Kashyap Desai wrote: > Is there any changes in API blk_queue_virt_boundary? I could not find > relevant code which account for this. Can you help ? > Which git repo shall I use for testing ? That way I can confirm, I didn't > miss relevant changes. Latest mainline plus the series (which is about to get resent). blk_queue_virt_boundary now forced an unlimited max_hw_sectors as that is how PRP-like schemes work, to work around a block driver merging bug. But we also need to communicate that limit to the DMA layer so that we don't set a smaller iommu segment size limitation. > >From your above explanation, it means (after this patch) max segment size > of the MR controller will be set to 4K. > Earlier it is possible to receive single SGE of 64K datalength (Since max > seg size was 64K), but now the same buffer will reach the driver having 16 > SGEs (Each SGE will contain 4K length). No, there is no more limit for the size of the segment at all, as for PRPs each PRP is sort of a segment from the hardware perspective. We just require the segments to not have gaps, as PRPs don't allow for that. That being said I think these patches are wrong for the case of megaraid or mpt having both NVMe and SAS/ATA devices behind a single controller. Is that a valid configuration?
WARNING: multiple messages have this Message-ID (diff)
From: hch@lst.de (Christoph Hellwig) Subject: [PATCH 10/13] megaraid_sas: set virt_boundary_mask in the scsi host Date: Mon, 17 Jun 2019 10:44:33 +0200 [thread overview] Message-ID: <20190617084433.GA7969@lst.de> (raw) In-Reply-To: <98f6557ae91a7cdfe8069fcf7d788c88@mail.gmail.com> On Fri, Jun 14, 2019@01:28:47AM +0530, Kashyap Desai wrote: > Is there any changes in API blk_queue_virt_boundary? I could not find > relevant code which account for this. Can you help ? > Which git repo shall I use for testing ? That way I can confirm, I didn't > miss relevant changes. Latest mainline plus the series (which is about to get resent). blk_queue_virt_boundary now forced an unlimited max_hw_sectors as that is how PRP-like schemes work, to work around a block driver merging bug. But we also need to communicate that limit to the DMA layer so that we don't set a smaller iommu segment size limitation. > >From your above explanation, it means (after this patch) max segment size > of the MR controller will be set to 4K. > Earlier it is possible to receive single SGE of 64K datalength (Since max > seg size was 64K), but now the same buffer will reach the driver having 16 > SGEs (Each SGE will contain 4K length). No, there is no more limit for the size of the segment at all, as for PRPs each PRP is sort of a segment from the hardware perspective. We just require the segments to not have gaps, as PRPs don't allow for that. That being said I think these patches are wrong for the case of megaraid or mpt having both NVMe and SAS/ATA devices behind a single controller. Is that a valid configuration?
next prev parent reply other threads:[~2019-06-17 8:45 UTC|newest] Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-06-05 19:08 properly communicate queue limits to the DMA layer Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 01/13] nvme-pci: don't limit DMA segement size Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 02/13] rsxx: don't call dma_set_max_seg_size Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 03/13] mtip32xx: also set max_segment_size in the device Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 04/13] mmc: " Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 05/13] scsi: add a host / host template field for the virt boundary Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 06/13] ufshcd: set max_segment_size in the scsi host template Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 07/13] storvsc: set virt_boundary_mask " Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 08/13] IB/iser: set virt_boundary_mask in the scsi host Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 20:22 ` Jason Gunthorpe 2019-06-05 20:22 ` Jason Gunthorpe 2019-06-05 23:35 ` Sagi Grimberg 2019-06-05 23:35 ` Sagi Grimberg 2019-06-06 6:24 ` Christoph Hellwig 2019-06-06 6:24 ` Christoph Hellwig 2019-06-06 12:59 ` Jason Gunthorpe 2019-06-06 12:59 ` Jason Gunthorpe 2019-06-06 14:19 ` Christoph Hellwig 2019-06-06 14:19 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 09/13] IB/srp: " Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 10/13] megaraid_sas: " Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-06 6:02 ` Hannes Reinecke 2019-06-06 6:02 ` Hannes Reinecke 2019-06-06 6:41 ` Christoph Hellwig 2019-06-06 6:41 ` Christoph Hellwig 2019-06-06 15:37 ` Kashyap Desai 2019-06-06 15:37 ` Kashyap Desai 2019-06-08 8:14 ` Christoph Hellwig 2019-06-08 8:14 ` Christoph Hellwig 2019-06-13 19:58 ` Kashyap Desai 2019-06-13 19:58 ` Kashyap Desai 2019-06-13 19:58 ` Kashyap Desai 2019-06-17 8:44 ` Christoph Hellwig [this message] 2019-06-17 8:44 ` Christoph Hellwig 2019-06-17 9:10 ` Kashyap Desai 2019-06-17 9:10 ` Kashyap Desai 2019-06-13 8:44 ` Christoph Hellwig 2019-06-13 8:44 ` Christoph Hellwig 2019-06-13 20:04 ` Kashyap Desai 2019-06-13 20:04 ` Kashyap Desai 2019-06-05 19:08 ` [PATCH 11/13] mpt3sas: " Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 12/13] usb-storage: " Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:08 ` [PATCH 13/13] uas: " Christoph Hellwig 2019-06-05 19:08 ` Christoph Hellwig 2019-06-05 19:17 ` properly communicate queue limits to the DMA layer Jens Axboe 2019-06-05 19:17 ` Jens Axboe 2019-06-05 19:24 ` Christoph Hellwig 2019-06-05 19:24 ` Christoph Hellwig 2019-06-07 5:52 ` Jens Axboe 2019-06-07 5:52 ` Jens Axboe 2019-06-07 17:30 ` Martin K. Petersen 2019-06-07 17:30 ` Martin K. Petersen 2019-06-08 8:10 ` Jens Axboe 2019-06-08 8:10 ` Jens Axboe
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