Messages in this thread | | | Date | Sat, 9 May 2020 10:23:52 +0200 | From | Christoph Hellwig <> | Subject | Re: remove a few uses of ->queuedata |
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On Fri, May 08, 2020 at 11:04:45AM -0700, Dan Williams wrote: > On Fri, May 8, 2020 at 9:16 AM Christoph Hellwig <hch@lst.de> wrote: > > > > Hi all, > > > > various bio based drivers use queue->queuedata despite already having > > set up disk->private_data, which can be used just as easily. This > > series cleans them up to only use a single private data pointer. > > ...but isn't the queue pretty much guaranteed to be cache hot and the > gendisk cache cold? I'm not immediately seeing what else needs the > gendisk in the I/O path. Is there another motivation I'm missing?
->private_data is right next to the ->queue pointer, pat0 and part_tbl which are all used in the I/O submission path (generic_make_request / generic_make_request_checks). This is mostly a prep cleanup patch to also remove the pointless queue argument from ->make_request - then ->queue is an extra dereference and extra churn.
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