2018-04-05 22:29 GMT+08:00 Jens Axboe <axboe@xxxxxxxxx>: > On 4/5/18 4:09 AM, Weiping Zhang wrote: >> Hi, >> >> 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, thanks you. > > _______________________________________________ > Virtualization mailing list > Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linuxfoundation.org/mailman/listinfo/virtualization
