Messages in this thread | | | Date | Tue, 22 Oct 2013 20:55:37 +0200 | From | Matias Bjorling <> | Subject | Re: [PATCH 3/3] NVMe: Convert to blk-mq |
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Den 22-10-2013 18:55, Keith Busch skrev: > On Fri, 18 Oct 2013, Matias Bjørling wrote: >> On 10/18/2013 05:13 PM, Keith Busch wrote: >>> On Fri, 18 Oct 2013, Matias Bjorling wrote: >>>> The nvme driver implements itself as a bio-based driver. This >>>> primarily >>>> because of high lock congestion for high-performance nvm devices. To >>>> remove the congestion within the traditional block layer, a >>>> multi-queue >>>> block layer is being implemented. > >>>> - result = nvme_map_bio(nvmeq, iod, bio, dma_dir, psegs); >>>> - if (result <= 0) >>>> + if (nvme_map_rq(nvmeq, iod, rq, dma_dir)) >>>> goto free_cmdid; >>>> - length = result; >>>> >>>> - cmnd->rw.command_id = cmdid; >>>> + length = blk_rq_bytes(rq); >>>> + >>>> + cmnd->rw.command_id = rq->tag; >>> >>> The command ids have to be unique on a submission queue. Since each >>> namespace's blk-mq has its own 'tags' used as command ids here but >>> share >>> submission queues, what's stopping the tags for commands sent to >>> namespace >>> 1 from clashing with tags for namespace 2? >>> >>> I think this would work better if one blk-mq was created per device >>> rather than namespace. It would fix the tag problem above and save a >>> lot of memory potentially wasted on millions of requests allocated that >>> can't be used. >> >> You're right. I didn't see the connection. In v3 I'll push struct >> request_queue to nvme_dev and map the queues appropriately. It will >> also fix the command id issues. > > Just anticipating a possible issue with the suggestion. Will this > separate > the logical block size from the request_queue? Each namespace can have > a different format, so the block size and request_queue can't be tied > together like it currently is for this to work.
If only a couple of different logical sizes are to be expected (1-4), we can keep a list of already initialized request queues, and use the one that match an already initialized?
Axboe, do you know of a better solution? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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