Re: [PATCH v7] NVMe: conversion to blk-mq

Matias Bjørling
2014-06-11T22:22:59Z

On Wed, Jun 11, 2014 at 7:09 PM, Matthew Wilcox <willy@linux.intel.com> wrote:
> On Wed, Jun 11, 2014 at 10:54:52AM -0600, Jens Axboe wrote:
>> OK, so essentially any single request must be a virtually contig piece
>> of memory. Is there any size limitations to how big this contig segment
>> can be?
>
> The maximum size of an I/O is 65536 sectors. So on a 512-byte sector
> device, that's 32MB, but on a 4k sector size device, that's 128MB.
>
>> I think this is unique requirement, at least I haven't seen other pieces
>> of hardware have it. But it would be pretty trivial to add a setting to
>> limit merges based on virtually contig, similarly to what is done for
>> number of physical segments.
>
> I think there might be an FCoE device with that requirement too.

I've rebased nvmemq_review and added two patches from Jens that add
support for requests with single range virtual addresses.

Keith, will you take it for a spin and see if it fixes 068 for you?

There might still be a problem with some flushes, I'm looking into this.