On Wed, Mar 12, 2014 at 5:19 PM, Jens Axboe <[email protected]> wrote: > On 03/12/2014 11:18 AM, David Vrabel wrote: >> >> On 12/03/14 17:08, Felipe Franciosi wrote: >>> >>> On Wed, Mar 12, 2014 at 4:16 PM, Jens Axboe <[email protected]> wrote: >>>> >>>> >>>> On 03/12/2014 10:05 AM, Felipe Franciosi wrote: >>>>> >>>>> >>>>> This device support 64-bit DMA and therefore no IO requests needs >>>>> bouncing. >>>>> On 32-bit systems, blk_queue_bounce() will bounce all IO requests with >>>>> high >>>>> mem pages. This makes performance really really bad. >> >> [...] >>>>> >>>>> --- a/drivers/block/mtip32xx/mtip32xx.c >>>>> +++ b/drivers/block/mtip32xx/mtip32xx.c >>>>> @@ -4082,8 +4082,6 @@ static void mtip_make_request(struct >>>>> request_queue *queue, struct bio *bio) >>>>> >>>>> sg = mtip_hw_get_scatterlist(dd, &tag, unaligned); >>>>> if (likely(sg != NULL)) { >>>>> - blk_queue_bounce(queue, &bio); >>>>> - >>>>> if (unlikely((bio)->bi_vcnt > MTIP_MAX_SG)) { >>>>> dev_warn(&dd->pdev->dev, >>>>> "Maximum number of SGL entries >>>>> exceeded\n"); >>>> >>>> >>>> >>>> That seems to be because the driver forgets to set the DMA >>>> capabilities. It needs a blk_queue_bounce_limit() call when it sets up >>>> the queue. >>> >>> >>> Hmm... I see what you are saying. David, would you like to comment? >> >> >> Yes, it should also call blk_queue_bounce_limit(..., BLK_BOUNCE_ANY) in >> mtip_block_initialize() as well. >> >> But, only one other driver calls blk_queue_bounce() so it's difficult to >> see why this driver would need a call here. > > > That's because most other drivers hook in the appropriate place, and the > blk_queue_bounce() is then done by the block layer. > > -- > Jens Axboe >
I'll add the blk_queue_bounce_limit() on the initialisation, test it out and submit a v2 tomorrow. Cheers, Felipe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
