On Mon, 25 May 2009 12:28:01 +0300 Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote: > On 05/25/2009 10:30 AM, Jens Axboe wrote: > > Fold the sense buffer into the command, thereby eliminating a slab > > allocation and free per command. > > > > Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx> > > Jens Hi. > > I'm "TO:" this to Tomo. > > This is the way it used to be for a long time. It was only recently changed by > Tomo because of a bug on none-cache-coherent arches that need to dma-access the > sense_buffer and also on the other hand change scsi_cmnd members by CPU. > > In my opinion all you need is an __aligned(SMP_CACHE_BYTES) declaration at > sense_buffer[] and let there be a hole at the end before the array. But Tomo > did not like that, so he separated the two. IIRC, it was not my opinion :) I don't think that putting CACHE_ALIGNMENT here is a good idea though. If this separated sense buffer allocation actually hurts the performance, then I prefer the ->alloc_cmnd and ->destroy_cmnd hook idea. Then most of llds are happy about the current sense buffer scheme and some can use ->alloc_cmnd and ->destroy_cmnd hooks for the better performance. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
