2018-04-05 22:29 GMT+08:00 Jens Axboe <ax...@kernel.dk>:
> On 4/5/18 4:09 AM, Weiping Zhang wrote:
>> For virtio block device, actually there is no a hard limit for max request
>> size, and virtio_blk driver set -1 to blk_queue_max_hw_sectors(q, -1U);.
>> But it doesn't work, because there is a default upper limitation
>> BLK_DEF_MAX_SECTORS (1280 sectors). So this series want to add a new helper
>> blk_queue_max_hw_sectors_no_limit to set a proper max reqeust size.
>> Weiping Zhang (2):
>> blk-setting: add new helper blk_queue_max_hw_sectors_no_limit
>> virtio_blk: add new module parameter to set max request size
>> block/blk-settings.c | 20 ++++++++++++++++++++
>> drivers/block/virtio_blk.c | 32 ++++++++++++++++++++++++++++++--
>> include/linux/blkdev.h | 2 ++
>> 3 files changed, 52 insertions(+), 2 deletions(-)
> The driver should just use blk_queue_max_hw_sectors() to set the limit,
> and then the soft limit can be modified by a udev rule. Technically the
> driver doesn't own the software limit, it's imposed to ensure that we
> don't introduce too much latency per request.
> Your situation is no different from many other setups, where the
> hw limit is much higher than the default 1280k.
Hi Martin, Jens,
It seems more reasonable to change software limitation by udev rule,
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