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. David -- 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/
